| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="The `Error` trait allows `Deserialize` implementations to create descriptive error messages belonging to the `Deserializer` against which they are currently running."><meta name="keywords" content="rust, rustlang, rust-lang, Error"><title>Error in serde::de - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc trait"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../serde/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../serde/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">Error</a></h2><div class="sidebar-elems"><section><h3><a href="#required-methods">Required Methods</a></h3><ul class="block"><li><a href="#tymethod.custom">custom</a></li></ul><h3><a href="#provided-methods">Provided Methods</a></h3><ul class="block"><li><a href="#method.duplicate_field">duplicate_field</a></li><li><a href="#method.invalid_length">invalid_length</a></li><li><a href="#method.invalid_type">invalid_type</a></li><li><a href="#method.invalid_value">invalid_value</a></li><li><a href="#method.missing_field">missing_field</a></li><li><a href="#method.unknown_field">unknown_field</a></li><li><a href="#method.unknown_variant">unknown_variant</a></li></ul><h3><a href="#implementors">Implementors</a></h3></section><h2><a href="index.html">In serde::de</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Trait <a href="../index.html">serde</a>::<wbr><a href="index.html">de</a>::<wbr><a class="trait" href="#">Error</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../../src/serde/de/mod.rs.html#299">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust trait"><code>pub trait Error: Sized + StdError { |
| fn <a href="#tymethod.custom" class="fnname">custom</a><T>(msg: T) -> Self<br> <span class="where">where<br> T: Display</span>; |
| |
| fn <a href="#method.invalid_type" class="fnname">invalid_type</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a><'_>, exp: &dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -> Self { ... } |
| <span class="item-spacer"></span> fn <a href="#method.invalid_value" class="fnname">invalid_value</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a><'_>, exp: &dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -> Self { ... } |
| <span class="item-spacer"></span> fn <a href="#method.invalid_length" class="fnname">invalid_length</a>(len: usize, exp: &dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -> Self { ... } |
| <span class="item-spacer"></span> fn <a href="#method.unknown_variant" class="fnname">unknown_variant</a>(variant: &str, expected: &'static [&'static str]) -> Self { ... } |
| <span class="item-spacer"></span> fn <a href="#method.unknown_field" class="fnname">unknown_field</a>(field: &str, expected: &'static [&'static str]) -> Self { ... } |
| <span class="item-spacer"></span> fn <a href="#method.missing_field" class="fnname">missing_field</a>(field: &'static str) -> Self { ... } |
| <span class="item-spacer"></span> fn <a href="#method.duplicate_field" class="fnname">duplicate_field</a>(field: &'static str) -> Self { ... } |
| }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>The <code>Error</code> trait allows <code>Deserialize</code> implementations to create descriptive |
| error messages belonging to the <code>Deserializer</code> against which they are |
| currently running.</p> |
| <p>Every <code>Deserializer</code> declares an <code>Error</code> type that encompasses both |
| general-purpose deserialization errors as well as errors specific to the |
| particular deserialization format. For example the <code>Error</code> type of |
| <code>serde_json</code> can represent errors like an invalid JSON escape sequence or an |
| unterminated string literal, in addition to the error cases that are part of |
| this trait.</p> |
| <p>Most deserializers should only need to provide the <code>Error::custom</code> method |
| and inherit the default behavior for the other methods.</p> |
| <h2 id="example-implementation"><a href="#example-implementation">Example implementation</a></h2> |
| <p>The <a href="https://serde.rs/data-format.html">example data format</a> presented on the website shows an error |
| type appropriate for a basic JSON data format.</p> |
| </div></details><h2 id="required-methods" class="small-section-header">Required Methods<a href="#required-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle method-toggle" open><summary><section id="tymethod.custom" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#tymethod.custom" class="fnname">custom</a><T>(msg: T) -> Self<span class="where fmt-newline">where<br> T: Display,</span></h4></section></summary><div class="docblock"><p>Raised when there is general error when deserializing a type.</p> |
| <p>The message should not be capitalized and should not end with a period.</p> |
| |
| <div class="example-wrap edition"><div class='tooltip' data-edition="2018">ⓘ</div><pre class="rust rust-example-rendered"><code><span class="kw">use </span>serde::de::{<span class="self">self</span>, Deserialize, Deserializer}; |
| |
| <span class="kw">impl</span><<span class="lifetime">'de</span>> Deserialize<<span class="lifetime">'de</span>> <span class="kw">for </span>IpAddr { |
| <span class="kw">fn </span>deserialize<D>(deserializer: D) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>, D::Error> |
| <span class="kw">where |
| </span>D: Deserializer<<span class="lifetime">'de</span>>, |
| { |
| <span class="kw">let </span>s = String::deserialize(deserializer)<span class="question-mark">?</span>; |
| s.parse().map_err(de::Error::custom) |
| } |
| }</code></pre></div> |
| </div></details></div><h2 id="provided-methods" class="small-section-header">Provided Methods<a href="#provided-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.invalid_type" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#method.invalid_type" class="fnname">invalid_type</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a><'_>, exp: &dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -> Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> receives a type different from what it was |
| expecting.</p> |
| <p>The <code>unexp</code> argument provides information about what type was received. |
| This is the type that was present in the input file or other source data |
| of the Deserializer.</p> |
| <p>The <code>exp</code> argument provides information about what type was being |
| expected. This is the type that is written in the program.</p> |
| <p>For example if we try to deserialize a String out of a JSON file |
| containing an integer, the unexpected type is the integer and the |
| expected type is the string.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.invalid_value" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#method.invalid_value" class="fnname">invalid_value</a>(unexp: <a class="enum" href="enum.Unexpected.html" title="enum serde::de::Unexpected">Unexpected</a><'_>, exp: &dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -> Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> receives a value of the right type but that |
| is wrong for some other reason.</p> |
| <p>The <code>unexp</code> argument provides information about what value was received. |
| This is the value that was present in the input file or other source |
| data of the Deserializer.</p> |
| <p>The <code>exp</code> argument provides information about what value was being |
| expected. This is the type that is written in the program.</p> |
| <p>For example if we try to deserialize a String out of some binary data |
| that is not valid UTF-8, the unexpected value is the bytes and the |
| expected value is a string.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.invalid_length" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#method.invalid_length" class="fnname">invalid_length</a>(len: usize, exp: &dyn <a class="trait" href="trait.Expected.html" title="trait serde::de::Expected">Expected</a>) -> Self</h4></section></summary><div class="docblock"><p>Raised when deserializing a sequence or map and the input data contains |
| too many or too few elements.</p> |
| <p>The <code>len</code> argument is the number of elements encountered. The sequence |
| or map may have expected more arguments or fewer arguments.</p> |
| <p>The <code>exp</code> argument provides information about what data was being |
| expected. For example <code>exp</code> might say that a tuple of size 6 was |
| expected.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.unknown_variant" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#method.unknown_variant" class="fnname">unknown_variant</a>(variant: &str, expected: &'static [&'static str]) -> Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> enum type received a variant with an |
| unrecognized name.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.unknown_field" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#method.unknown_field" class="fnname">unknown_field</a>(field: &str, expected: &'static [&'static str]) -> Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> struct type received a field with an |
| unrecognized name.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.missing_field" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#method.missing_field" class="fnname">missing_field</a>(field: &'static str) -> Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> struct type expected to receive a required |
| field with a particular name but that field was not present in the |
| input.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.duplicate_field" class="method has-srclink"><a class="srclink rightside" href="../../src/serde/de/mod.rs.html#299">source</a><h4 class="code-header">fn <a href="#method.duplicate_field" class="fnname">duplicate_field</a>(field: &'static str) -> Self</h4></section></summary><div class="docblock"><p>Raised when a <code>Deserialize</code> struct type received more than one of the |
| same field.</p> |
| </div></details></div><h2 id="implementors" class="small-section-header">Implementors<a href="#implementors" class="anchor"></a></h2><div id="implementors-list"><section id="impl-Error-for-Error" class="impl has-srclink"><a class="srclink rightside" href="../../src/serde/de/value.rs.html#61-82">source</a><a href="#impl-Error-for-Error" class="anchor"></a><h3 class="code-header">impl <a class="trait" href="trait.Error.html" title="trait serde::de::Error">Error</a> for <a class="struct" href="value/struct.Error.html" title="struct serde::de::value::Error">Error</a></h3></section></div><script src="../../implementors/serde/de/trait.Error.js" async></script></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="serde" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
