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class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-2 menu__list-item menu__list-item--collapsed"><div class=menu__list-item-collapsible><a class="categoryLink_byQd menu__link menu__link--sublist" tabindex=0 href=/docs/guide/xlang/><span title="Cross Language" class=categoryLinkLabel_W154>Cross Language</span></a><button aria-label="Expand sidebar category 'Cross Language'" aria-expanded=false type=button class="clean-btn menu__caret"></button></div></ul></ul></nav></div></div></aside><main class=docMainContainer_TBSr><div class="container padding-top--md padding-bottom--lg"><div class=row><div class="col docItemCol_VOVn"><div class=docItemContainer_Djhp><article><nav class="theme-doc-breadcrumbs breadcrumbsContainer_Z_bl" aria-label=Breadcrumbs><ul class=breadcrumbs><li class=breadcrumbs__item><a aria-label="Home page" class=breadcrumbs__link href=/><svg viewBox="0 0 24 24" class=breadcrumbHomeIcon_YNFT><path d="M10 19v-5h4v5c0 .55.45 1 1 1h3c.55 0 1-.45 1-1v-7h1.7c.46 0 .68-.57.33-.87L12.67 3.6c-.38-.34-.96-.34-1.34 0l-8.36 7.53c-.34.3-.13.87.33.87H5v7c0 .55.45 1 1 1h3c.55 0 1-.45 1-1z" fill=currentColor /></svg></a><li class=breadcrumbs__item><span class=breadcrumbs__link>Guide</span><li class=breadcrumbs__item><a class=breadcrumbs__link href=/docs/guide/go/><span>Go</span></a><li class="breadcrumbs__item breadcrumbs__item--active"><span class=breadcrumbs__link>Custom Serializers</span></ul></nav><span class="theme-doc-version-badge badge badge--secondary">Version: 1.3.0</span><div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type=button class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>Custom Serializers</h1></header><p>Custom serializers allow you to define exactly how a type is serialized and deserialized. This is useful for types that require special handling, optimization, or cross-language compatibility.</p>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=when-to-use-custom-serializers>When to Use Custom Serializers<a href=#when-to-use-custom-serializers class=hash-link aria-label="Direct link to When to Use Custom Serializers" title="Direct link to When to Use Custom Serializers" translate=no>​</a></h2>
<ul>
<li class=""><strong>Special encoding</strong>: Types that need a specific binary format</li>
<li class=""><strong>Third-party types</strong>: Types from external libraries that Fory doesn't handle automatically</li>
<li class=""><strong>Optimization</strong>: When you can serialize more efficiently than the default reflection-based approach</li>
<li class=""><strong>Cross-language compatibility</strong>: When you need precise control over the binary format for interoperability</li>
</ul>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=extensionserializer-interface>ExtensionSerializer Interface<a href=#extensionserializer-interface class=hash-link aria-label="Direct link to ExtensionSerializer Interface" title="Direct link to ExtensionSerializer Interface" translate=no>​</a></h2>
<p>Custom serializers implement the <code>ExtensionSerializer</code> interface:</p>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token keyword" style=color:#00009f>type</span><span class="token plain"> ExtensionSerializer </span><span class="token keyword" style=color:#00009f>interface</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// WriteData serializes the value to the buffer.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Only write the data - Fory handles type info and references.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Use ctx.Buffer() to access the ByteBuffer.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Use ctx.SetError() to report errors.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token function" style=color:#d73a49>WriteData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">WriteContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// ReadData deserializes the value from the buffer into the provided value.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Only read the data - Fory handles type info and references.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Use ctx.Buffer() to access the ByteBuffer.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Use ctx.SetError() to report errors.</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token function" style=color:#d73a49>ReadData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">ReadContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><br/></div></code></pre></div></div>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=basic-example>Basic Example<a href=#basic-example class=hash-link aria-label="Direct link to Basic Example" title="Direct link to Basic Example" translate=no>​</a></h2>
<p>Here's a simple custom serializer for a type with an integer field:</p>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token keyword" style=color:#00009f>import</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token string" style=color:#e3116c>"reflect"</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token string" style=color:#e3116c>"github.com/apache/fory/go/fory"</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>type</span><span class="token plain"> MyExt </span><span class="token keyword" style=color:#00009f>struct</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> Id </span><span class="token builtin">int32</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>type</span><span class="token plain"> MyExtSerializer </span><span class="token keyword" style=color:#00009f>struct</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">s </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">MyExtSerializer</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>WriteData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">WriteContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> myExt </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Interface</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>.</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">MyExt</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Buffer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteVarint32</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">myExt</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Id</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">s </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">MyExtSerializer</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>ReadData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">ReadContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> id </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Buffer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadVarint32</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Err</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Set</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ValueOf</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">MyExt</span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain">Id</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> id</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token comment" style=color:#999988;font-style:italic>// Register the custom serializer</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain">f </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>New</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WithXlang</span><span class="token punctuation" style=color:#393A34>(</span><span class="token boolean" style=color:#36acaa>true</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain">err </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> f</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>RegisterExtension</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">MyExt</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token number" style=color:#36acaa>100</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>&</span><span class="token plain">MyExtSerializer</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><br/></div></code></pre></div></div>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=context-methods>Context Methods<a href=#context-methods class=hash-link aria-label="Direct link to Context Methods" title="Direct link to Context Methods" translate=no>​</a></h2>
<p>The <code>WriteContext</code> and <code>ReadContext</code> provide access to serialization resources:</p>
<table><thead><tr><th>Method<th>Description<tbody><tr><td><code>Buffer()</code><td>Returns the <code>*ByteBuffer</code> for reading/writing<tr><td><code>Err()</code><td>Returns <code>*Error</code> for deferred error checking<tr><td><code>SetError(err)</code><td>Sets an error on the context<tr><td><code>HasError()</code><td>Returns true if an error has been set<tr><td><code>TypeResolver()</code><td>Returns the type resolver for nested types<tr><td><code>RefResolver()</code><td>Returns the reference resolver for ref support</table>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=bytebuffer-methods>ByteBuffer Methods<a href=#bytebuffer-methods class=hash-link aria-label="Direct link to ByteBuffer Methods" title="Direct link to ByteBuffer Methods" translate=no>​</a></h2>
<p>The <code>ByteBuffer</code> provides methods for reading and writing primitive types:</p>
<h3 class="anchor anchorTargetStickyNavbar_Vzrq" id=writing-methods>Writing Methods<a href=#writing-methods class=hash-link aria-label="Direct link to Writing Methods" title="Direct link to Writing Methods" translate=no>​</a></h3>
<table><thead><tr><th>Method<th>Description<tbody><tr><td><code>WriteBool(v bool)</code><td>Write a boolean<tr><td><code>WriteInt8(v int8)</code><td>Write a signed 8-bit integer<tr><td><code>WriteInt16(v int16)</code><td>Write a signed 16-bit integer<tr><td><code>WriteInt32(v int32)</code><td>Write a signed 32-bit integer<tr><td><code>WriteInt64(v int64)</code><td>Write a signed 64-bit integer<tr><td><code>WriteFloat32(v float32)</code><td>Write a 32-bit float<tr><td><code>WriteFloat64(v float64)</code><td>Write a 64-bit float<tr><td><code>WriteVarint32(v int32)</code><td>Write a variable-length signed 32-bit integer<tr><td><code>WriteVarint64(v int64)</code><td>Write a variable-length signed 64-bit integer<tr><td><code>WriteBinary(data []byte)</code><td>Write raw bytes</table>
<h3 class="anchor anchorTargetStickyNavbar_Vzrq" id=reading-methods>Reading Methods<a href=#reading-methods class=hash-link aria-label="Direct link to Reading Methods" title="Direct link to Reading Methods" translate=no>​</a></h3>
<p>All read methods take an <code>*Error</code> parameter for deferred error checking:</p>
<table><thead><tr><th>Method<th>Description<tbody><tr><td><code>ReadBool(err *Error) bool</code><td>Read a boolean<tr><td><code>ReadInt8(err *Error) int8</code><td>Read a signed 8-bit integer<tr><td><code>ReadInt16(err *Error) int16</code><td>Read a signed 16-bit integer<tr><td><code>ReadInt32(err *Error) int32</code><td>Read a signed 32-bit integer<tr><td><code>ReadInt64(err *Error) int64</code><td>Read a signed 64-bit integer<tr><td><code>ReadFloat32(err *Error) float32</code><td>Read a 32-bit float<tr><td><code>ReadFloat64(err *Error) float64</code><td>Read a 64-bit float<tr><td><code>ReadVarint32(err *Error) int32</code><td>Read a variable-length signed 32-bit integer<tr><td><code>ReadVarint64(err *Error) int64</code><td>Read a variable-length signed 64-bit integer<tr><td><code>ReadBinary(length int, err *Error) []byte</code><td>Read raw bytes of specified length</table>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=complex-type-example>Complex Type Example<a href=#complex-type-example class=hash-link aria-label="Direct link to Complex Type Example" title="Direct link to Complex Type Example" translate=no>​</a></h2>
<p>A custom serializer for a type with multiple fields:</p>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token keyword" style=color:#00009f>type</span><span class="token plain"> Point3D </span><span class="token keyword" style=color:#00009f>struct</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> X</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> Y</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> Z </span><span class="token builtin">float64</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> Label </span><span class="token builtin">string</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>type</span><span class="token plain"> Point3DSerializer </span><span class="token keyword" style=color:#00009f>struct</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">s </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">Point3DSerializer</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>WriteData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">WriteContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> p </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Interface</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>.</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">Point3D</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Buffer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteFloat64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">p</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">X</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteFloat64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">p</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Y</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteFloat64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">p</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Z</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Write string as length + bytes</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> labelBytes </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>[</span><span class="token punctuation" style=color:#393A34>]</span><span class="token function" style=color:#d73a49>byte</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">p</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Label</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteVarint32</span><span class="token punctuation" style=color:#393A34>(</span><span class="token function" style=color:#d73a49>int32</span><span class="token punctuation" style=color:#393A34>(</span><span class="token function" style=color:#d73a49>len</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">labelBytes</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteBinary</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">labelBytes</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">s </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">Point3DSerializer</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>ReadData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">ReadContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Buffer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> err </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Err</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> x </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadFloat64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> y </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadFloat64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> z </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadFloat64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> labelLen </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadVarint32</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> labelBytes </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadBinary</span><span class="token punctuation" style=color:#393A34>(</span><span class="token function" style=color:#d73a49>int</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">labelLen</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Set</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ValueOf</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">Point3D</span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> X</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> x</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> Y</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> y</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> Z</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> z</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> Label</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>string</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">labelBytes</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain">f </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>New</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WithXlang</span><span class="token punctuation" style=color:#393A34>(</span><span class="token boolean" style=color:#36acaa>true</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain">f</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>RegisterExtension</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">Point3D</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token number" style=color:#36acaa>101</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>&</span><span class="token plain">Point3DSerializer</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><br/></div></code></pre></div></div>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=handling-pointers>Handling Pointers<a href=#handling-pointers class=hash-link aria-label="Direct link to Handling Pointers" title="Direct link to Handling Pointers" translate=no>​</a></h2>
<p>When your type contains pointers, handle nil values explicitly:</p>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token keyword" style=color:#00009f>type</span><span class="token plain"> OptionalValue </span><span class="token keyword" style=color:#00009f>struct</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> Value </span><span class="token operator" style=color:#393A34>*</span><span class="token builtin">int64</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>type</span><span class="token plain"> OptionalValueSerializer </span><span class="token keyword" style=color:#00009f>struct</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">s </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">OptionalValueSerializer</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>WriteData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">WriteContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> ov </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Interface</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>.</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">OptionalValue</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Buffer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>if</span><span class="token plain"> ov</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value </span><span class="token operator" style=color:#393A34>==</span><span class="token plain"> </span><span class="token boolean" style=color:#36acaa>nil</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteBool</span><span class="token punctuation" style=color:#393A34>(</span><span class="token boolean" style=color:#36acaa>false</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// nil flag</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"> </span><span class="token keyword" style=color:#00009f>else</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteBool</span><span class="token punctuation" style=color:#393A34>(</span><span class="token boolean" style=color:#36acaa>true</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// not nil</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WriteInt64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token operator" style=color:#393A34>*</span><span class="token plain">ov</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">s </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">OptionalValueSerializer</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>ReadData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">ReadContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Buffer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> err </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Err</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> hasValue </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadBool</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>if</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>!</span><span class="token plain">hasValue </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Set</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ValueOf</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">OptionalValue</span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> </span><span class="token boolean" style=color:#36acaa>nil</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>return</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> v </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadInt64</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Set</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ValueOf</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">OptionalValue</span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>&</span><span class="token plain">v</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><br/></div></code></pre></div></div>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=error-handling>Error Handling<a href=#error-handling class=hash-link aria-label="Direct link to Error Handling" title="Direct link to Error Handling" translate=no>​</a></h2>
<p>Use <code>ctx.SetError()</code> to report errors:</p>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">s </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">MySerializer</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>ReadData</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">ReadContext</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> value reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">Value</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> buf </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Buffer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> version </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> buf</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ReadInt8</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Err</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>if</span><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>HasError</span><span class="token punctuation" style=color:#393A34>(</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>return</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>if</span><span class="token plain"> version </span><span class="token operator" style=color:#393A34>!=</span><span class="token plain"> </span><span class="token number" style=color:#36acaa>1</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> ctx</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>SetError</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>DeserializationErrorf</span><span class="token punctuation" style=color:#393A34>(</span><span class="token string" style=color:#e3116c>"unsupported version: %d"</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> version</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>return</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Continue reading...</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> value</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Set</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">reflect</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>ValueOf</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">result</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><br/></div></code></pre></div></div>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=registration-options>Registration Options<a href=#registration-options class=hash-link aria-label="Direct link to Registration Options" title="Direct link to Registration Options" translate=no>​</a></h2>
<h3 class="anchor anchorTargetStickyNavbar_Vzrq" id=register-by-id>Register by ID<a href=#register-by-id class=hash-link aria-label="Direct link to Register by ID" title="Direct link to Register by ID" translate=no>​</a></h3>
<p>More compact serialization, requires ID coordination across languages:</p>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token plain">f</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>RegisterExtension</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">MyType</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token number" style=color:#36acaa>100</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>&</span><span class="token plain">MySerializer</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><br/></div></code></pre></div></div>
<h3 class="anchor anchorTargetStickyNavbar_Vzrq" id=register-by-name>Register by Name<a href=#register-by-name class=hash-link aria-label="Direct link to Register by Name" title="Direct link to Register by Name" translate=no>​</a></h3>
<p>More flexible but more serialization cost, type name included in serialized data:</p>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token plain">f</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>RegisterExtensionByName</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">MyType</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token string" style=color:#e3116c>"myapp.MyType"</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>&</span><span class="token plain">MySerializer</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><br/></div></code></pre></div></div>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=best-practices>Best Practices<a href=#best-practices class=hash-link aria-label="Direct link to Best Practices" title="Direct link to Best Practices" translate=no>​</a></h2>
<ol>
<li class=""><strong>Keep it simple</strong>: Only serialize what you need</li>
<li class=""><strong>Use variable-length integers</strong>: <code>WriteVarint32</code>/<code>WriteVarint64</code> for integers that are often small</li>
<li class=""><strong>Handle nil explicitly</strong>: Check for nil pointers and slices</li>
<li class=""><strong>Version your format</strong>: Consider adding a version byte for future compatibility</li>
<li class=""><strong>Test round-trips</strong>: Always verify that <code>Read(Write(value)) == value</code></li>
<li class=""><strong>Match read/write order</strong>: Read fields in exactly the same order you write them</li>
<li class=""><strong>Check errors</strong>: Use <code>ctx.HasError()</code> after reading to handle errors gracefully</li>
<li class=""><strong>Deploy before use</strong>: Always deploy the registered serializer to all services before sending data serialized with it. If a service receives data for an unregistered serializer, deserialization will fail</li>
</ol>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=testing-custom-serializers>Testing Custom Serializers<a href=#testing-custom-serializers class=hash-link aria-label="Direct link to Testing Custom Serializers" title="Direct link to Testing Custom Serializers" translate=no>​</a></h2>
<div class="language-go codeBlockContainer_Ckt0 theme-code-block" style=--prism-color:#393A34;--prism-background-color:#f6f8fa><div class=codeBlockContent_QJqH><pre tabindex=0 class="prism-code language-go codeBlock_bY9V thin-scrollbar" style=color:#393A34;background-color:#f6f8fa><code class=codeBlockLines_e6Vv><div class=token-line style=color:#393A34><span class="token keyword" style=color:#00009f>func</span><span class="token plain"> </span><span class="token function" style=color:#d73a49>TestMySerializer</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">t </span><span class="token operator" style=color:#393A34>*</span><span class="token plain">testing</span><span class="token punctuation" style=color:#393A34>.</span><span class="token plain">T</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> f </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>New</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">fory</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>WithXlang</span><span class="token punctuation" style=color:#393A34>(</span><span class="token boolean" style=color:#36acaa>true</span><span class="token punctuation" style=color:#393A34>)</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> f</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>RegisterExtension</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">MyType</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token number" style=color:#36acaa>100</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>&</span><span class="token plain">MySerializer</span><span class="token punctuation" style=color:#393A34>{</span><span class="token punctuation" style=color:#393A34>}</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> original </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> MyType</span><span class="token punctuation" style=color:#393A34>{</span><span class="token plain">Field</span><span class="token punctuation" style=color:#393A34>:</span><span class="token plain"> </span><span class="token string" style=color:#e3116c>"test"</span><span class="token punctuation" style=color:#393A34>}</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Serialize</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> data</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> err </span><span class="token operator" style=color:#393A34>:=</span><span class="token plain"> f</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Serialize</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">original</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> require</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>NoError</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">t</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token comment" style=color:#999988;font-style:italic>// Deserialize</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> </span><span class="token keyword" style=color:#00009f>var</span><span class="token plain"> result MyType</span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> err </span><span class="token operator" style=color:#393A34>=</span><span class="token plain"> f</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Deserialize</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">data</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> </span><span class="token operator" style=color:#393A34>&</span><span class="token plain">result</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> require</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>NoError</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">t</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> err</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain" style=display:inline-block></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"> assert</span><span class="token punctuation" style=color:#393A34>.</span><span class="token function" style=color:#d73a49>Equal</span><span class="token punctuation" style=color:#393A34>(</span><span class="token plain">t</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> original</span><span class="token punctuation" style=color:#393A34>,</span><span class="token plain"> result</span><span class="token punctuation" style=color:#393A34>)</span><span class="token plain"></span><br/></div><div class=token-line style=color:#393A34><span class="token plain"></span><span class="token punctuation" style=color:#393A34>}</span><br/></div></code></pre></div></div>
<h2 class="anchor anchorTargetStickyNavbar_Vzrq" id=related-topics>Related Topics<a href=#related-topics class=hash-link aria-label="Direct link to Related Topics" title="Direct link to Related Topics" translate=no>​</a></h2>
<ul>
<li class=""><a class="" href=/docs/guide/go/type_registration>Type Registration</a></li>
<li class=""><a class="" href=/docs/guide/go/supported_types>Supported Types</a></li>
<li class=""><a class="" href=/docs/guide/go/xlang_serialization>Xlang Serialization</a></li>
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