| <html><head> |
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| <title>2.3. Request Parameter Auto Binding</title><link rel="stylesheet" href="css/stylesheet.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.0"><link rel="home" href="index.html" title="Apache Click"><link rel="up" href="ch02.html" title="Chapter 2. Pages"><link rel="prev" href="ch02s02.html" title="2.2. Execution"><link rel="next" href="ch02s04.html" title="2.4. Security"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2.3. Request Parameter Auto Binding</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch02s02.html">Prev</a> </td><th width="60%" align="center">Chapter 2. Pages</th><td width="20%" align="right"> <a accesskey="n" href="ch02s04.html">Next</a></td></tr></table><hr></div><div class="sect1" title="2.3. Request Parameter Auto Binding"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="request-param-auto-binding"></a>2.3. Request Parameter Auto Binding</h2></div></div></div><p>Click will automatically bind any request parameter values to public |
| Page variable with the same name. You can also use the |
| <a xmlns:fo="http://www.w3.org/1999/XSL/Format" class="external" href="../../click-api/org/apache/click/util/Bindable.html" target="_blank">Bindable</a> |
| annotation to bind private and protected Page variables. When binding these |
| values Click will also attempt to convert them to the correct type. |
| </p><p>The best way to understand this is to walk through an example. Our |
| application receives a GET request: |
| </p><div class="literallayout"><p>http://localhost:8080/mycorp/customer-details.htm?<code class="varname">customerId</code>=<span class="symbol">7203</span></p></div><p>This request is automatically handled by our |
| <code class="classname">CustomerDetails</code> page: |
| </p><pre class="programlisting"><span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">package</span> com.mycorp.page; |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">public</span> <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">class</span> CustomerDetails <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">extends</span> Page { |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="pun">@Bindable</span> <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">protected</span> Integer <code class="varname">customerId</code>; |
| }</pre><p>After the CustomerDetails page has been created the |
| "<code class="varname">customerId</code>" request parameter value "<span class="symbol">7023</span>" |
| will be converted into an Integer and assigned to the public page variable |
| <code class="varname">customerId</code>. |
| </p><p>Another feature of Click is that any public Page variables are |
| automatically added to the page's model before it is rendered. This will |
| make these values available in the page template for display. In our example |
| the public <code class="varname">customerId</code> variable will be added to the Page |
| model and will be available for rendering in the page template. |
| </p><p>Our customer-details.htm page template contains: |
| </p><pre class="programlisting"><span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><html></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><body></span> |
| |
| Customer ID: <span class="symbol">$</span><code class="varname">customerId</code> |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></body></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></html></span></pre><p>After processing the request our page would be rendered as: |
| </p><div class="literallayout"><p>Customer ID: 7203</p></div><div class="sect2" title="2.3.1. Customizing Auto Binding"><div class="titlepage"><div><div><h3 class="title"><a name="customizing-auto-binding"></a>2.3.1. Customizing Auto Binding</h3></div></div></div><p>Auto binding supports the conversion of request string parameters |
| into the Java classes: Integer, Double, Boolean, Byte, Character, Short, |
| Long, Float, BigInteger, BigDecimal, String and the various Date classes. |
| </p><p>By default type conversion is performed by the |
| <a xmlns:fo="http://www.w3.org/1999/XSL/Format" class="external" href="../../click-api/org/apache/click/util/RequestTypeConverter.html" target="_blank">RequestTypeConverter</a> |
| class which is used by the ClickServlet method |
| <a xmlns:fo="http://www.w3.org/1999/XSL/Format" class="external" href="../../click-api/org/apache/click/ClickServlet.html#getTypeConverter()" target="_blank">getTypeConverter()</a>. |
| </p><p>If you need to add support for additional types, you would write your |
| own type converter class and specify it as a ClickServlet init parameter. |
| </p><p>For example if you wanted to automatically load a |
| <code class="classname">Customer</code> object from the database when a customer |
| id request parameter is specified, you could write your own type converter: |
| </p><pre class="programlisting"><span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">public</span> <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">class</span> CustomTypeConverter <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">extends</span> RequestTypeConverter { |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">private</span> CustomerService customerService = <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">new</span> CustomerService(); |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="com">/** |
| * @see RequestTypeConverter#convertValue(Object, Class) |
| */</span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">protected</span> Object convertValue(Object value, Class toType) { |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">if</span> (toType == Customer.<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">class</span>) { |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">return</span> customerService.getCustomerForId(value); |
| |
| } <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">else</span> { |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">return</span> <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">super</span>.convertValue(value, toType); |
| } |
| } |
| }</pre><p>This type converter would handle the following request: |
| </p><div class="literallayout"><p>http://localhost:8080/mycorp/customer-details.htm?<code class="varname">customer</code>=<span class="symbol">7203</span></p></div><p>This request will load the <code class="varname">customer</code> object from |
| the database using "<span class="symbol">7203</span>" as the customer id value. The |
| ClickServlet would then assign this <code class="varname">customer</code> object to |
| the matching page variable: |
| </p><pre class="programlisting"><span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">package</span> com.mycorp.page; |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">public</span> <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">class</span> CustomerDetails <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">extends</span> Page { |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="pun">@Bindable</span> <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="kwd">protected</span> Customer <code class="varname">customer</code>; |
| |
| }</pre><p>To make your custom type converter available you will need to |
| add an init parameter to ClickServlet in <code class="filename">web.xml</code>. For example: |
| </p><pre class="programlisting"><span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><web-app></span> |
| ... |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><servlet></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><servlet-name></span>ClickServlet<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></servlet-name></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><servlet-class></span>org.apache.click.ClickServlet<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></servlet-class></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><init-param></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><param-name></span>type-converter-class<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></param-name></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><param-value></span>com.mycorp.util.CustomTypeConverter<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></param-value></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></init-param></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><load-on-startup></span>0<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></load-on-startup></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></servlet></span> |
| |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><servlet-mapping></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><servlet-name></span>ClickServlet<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></servlet-name></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"><url-pattern></span>*.htm<span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></url-pattern></span> |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></servlet-mapping></span> |
| ... |
| <span xmlns:fo="http://www.w3.org/1999/XSL/Format" class="tag"></web-app></span></pre></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch02s02.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch02.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch02s04.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2.2. Execution </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 2.4. Security</td></tr></table></div></body></html> |
