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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Serializing objects - objects in sessions</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="keyword.parent.html">parent</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.oop.magic-functions.html">The magic functions __sleep and __wakeup</a></div> <div class="up"><a href="language.oop.html">Classes and Objects (PHP 4)</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="language.oop.serialization" class="sect1"> <h2 class="title">Serializing objects - objects in sessions</h2> <p class="para"> <a href="function.serialize.html" class="function">serialize()</a> returns a string containing a byte-stream representation of any value that can be stored in PHP. <a href="function.unserialize.html" class="function">unserialize()</a> can use this string to recreate the original variable values. Using serialize to save an object will save all variables in an object. The functions in an object will not be saved, only the name of the class. </p> <p class="para"> In order to be able to <a href="function.unserialize.html" class="function">unserialize()</a> an object, the class of that object needs to be defined. That is, if you have an object <var class="varname">$a</var> of class A on page1.php and serialize this, you'll get a string that refers to class A and contains all values of variabled contained in <var class="varname">$a</var>. If you want to be able to unserialize this on page2.php, recreating <var class="varname">$a</var> of class A, the definition of class A must be present in page2.php. This can be done for example by storing the class definition of class A in an include file and including this file in both page1.php and page2.php. </p> <div class="informalexample"> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// classa.inc:<br /> <br /> </span><span style="color: #007700">class </span><span style="color: #0000BB">A </span><span style="color: #007700">{<br /> var </span><span style="color: #0000BB">$one </span><span style="color: #007700">= </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br /> <br /> function </span><span style="color: #0000BB">show_one</span><span style="color: #007700">() {<br /> echo </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">one</span><span style="color: #007700">;<br /> }<br /> }<br /> <br /></span><span style="color: #FF8000">// page1.php:<br /><br /> </span><span style="color: #007700">include(</span><span style="color: #DD0000">"classa.inc"</span><span style="color: #007700">);<br /> <br /> </span><span style="color: #0000BB">$a </span><span style="color: #007700">= new </span><span style="color: #0000BB">A</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$s </span><span style="color: #007700">= </span><span style="color: #0000BB">serialize</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">);<br /> </span><span style="color: #FF8000">// store $s somewhere where page2.php can find it.<br /> </span><span style="color: #0000BB">$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">"store"</span><span style="color: #007700">, </span><span style="color: #DD0000">"w"</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">$s</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// page2.php:<br /> <br /> // this is needed for the unserialize to work properly.<br /> </span><span style="color: #007700">include(</span><span style="color: #DD0000">"classa.inc"</span><span style="color: #007700">);<br /><br /> </span><span style="color: #0000BB">$s </span><span style="color: #007700">= </span><span style="color: #0000BB">implode</span><span style="color: #007700">(</span><span style="color: #DD0000">""</span><span style="color: #007700">, @</span><span style="color: #0000BB">file</span><span style="color: #007700">(</span><span style="color: #DD0000">"store"</span><span style="color: #007700">));<br /> </span><span style="color: #0000BB">$a </span><span style="color: #007700">= </span><span style="color: #0000BB">unserialize</span><span style="color: #007700">(</span><span style="color: #0000BB">$s</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">// now use the function show_one() of the $a object. <br /> </span><span style="color: #0000BB">$a</span><span style="color: #007700">-></span><span style="color: #0000BB">show_one</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> <p class="para"> If you are using sessions and use <a href="function.session-register.html" class="function">session_register()</a> to register objects, these objects are serialized automatically at the end of each PHP page, and are unserialized automatically on each of the following pages. This basically means that these objects can show up on any of your pages once they become part of your session. </p> <p class="para"> It is strongly recommended that you include the class definitions of all such registered objects on all of your pages, even if you do not actually use these classes on all of your pages. If you don't and an object is being unserialized without its class definition being present, it will lose its class association and become an object of class <i>stdClass</i> without any functions available at all, that is, it will become quite useless. </p> <p class="para"> So if in the example above <var class="varname">$a</var> became part of a session by running <i>session_register("a")</i>, you should include the file <i>classa.inc</i> on all of your pages, not only page1.php and page2.php. </p> </div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="keyword.parent.html">parent</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.oop.magic-functions.html">The magic functions __sleep and __wakeup</a></div> <div class="up"><a href="language.oop.html">Classes and Objects (PHP 4)</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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