<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML
><HEAD
><TITLE
>Serializing objects - objects in sessions</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
REL="HOME"
TITLE="PHP Handleiding"
HREF="index.html"><LINK
REL="UP"
TITLE="Classes and Objects (PHP 4)"
HREF="language.oop.html"><LINK
REL="PREVIOUS"
TITLE="parent"
HREF="keyword.parent.html"><LINK
REL="NEXT"
TITLE="The magic functions __sleep and __wakeup"
HREF="language.oop.magic-functions.html"><META
HTTP-EQUIV="Content-type"
CONTENT="text/html; charset=ISO-8859-1"></HEAD
><BODY
CLASS="sect1"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>PHP Handleiding</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="keyword.parent.html"
ACCESSKEY="P"
>Terug</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Hoofdstuk 13. Classes and Objects (PHP 4)</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="language.oop.magic-functions.html"
ACCESSKEY="N"
>Volgende</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="language.oop.serialization"
>Serializing objects - objects in sessions</A
></H1
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Opmerking: </B
>
In PHP 3, objects will lose their class association
throughout the process of serialization and unserialization.
The resulting variable is of type object, but has no class
and no methods, thus it is pretty useless (it has become
just like an array with a funny syntax).
</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="caution"
><P
></P
><TABLE
CLASS="caution"
BORDER="1"
WIDTH="100%"
><TR
><TD
ALIGN="CENTER"
><B
>Let op</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
> The following information is valid for PHP 4 only.
</P
></TD
></TR
></TABLE
></DIV
><P
> <A
HREF="function.serialize.html"
><B
CLASS="function"
>serialize()</B
></A
> returns a string containing a
byte-stream representation of any value that can be stored in
PHP. <A
HREF="function.unserialize.html"
><B
CLASS="function"
>unserialize()</B
></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
> In order to be able to <A
HREF="function.unserialize.html"
><B
CLASS="function"
>unserialize()</B
></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"
>$a</VAR
> of class A, the
definition of class A must be present in page2.php. This can be done for
example by storing the class definition of class A in an include file and
including this file in both page1.php and page2.php.
</P
><DIV
CLASS="informalexample"
><P
></P
><A
NAME="AEN4821"
></A
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#FF8000">// classa.inc:<br /> <br /> </font><font color="#007700">class </font><font color="#0000BB">A </font><font color="#007700">{<br /> var </font><font color="#0000BB">$one </font><font color="#007700">= </font><font color="#0000BB">1</font><font color="#007700">;<br /> <br /> function </font><font color="#0000BB">show_one</font><font color="#007700">() {<br /> echo </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">one</font><font color="#007700">;<br /> }<br /> }<br /> <br /></font><font color="#FF8000">// page1.php:<br /><br /> </font><font color="#007700">include(</font><font color="#DD0000">"classa.inc"</font><font color="#007700">);<br /> <br /> </font><font color="#0000BB">$a </font><font color="#007700">= new </font><font color="#0000BB">A</font><font color="#007700">;<br /> </font><font color="#0000BB">$s </font><font color="#007700">= </font><font color="#0000BB">serialize</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">);<br /> </font><font color="#FF8000">// store $s somewhere where page2.php can find it.<br /> </font><font color="#0000BB">$fp </font><font color="#007700">= </font><font color="#0000BB">fopen</font><font color="#007700">(</font><font color="#DD0000">"store"</font><font color="#007700">, </font><font color="#DD0000">"w"</font><font color="#007700">);<br /> </font><font color="#0000BB">fwrite</font><font color="#007700">(</font><font color="#0000BB">$fp</font><font color="#007700">, </font><font color="#0000BB">$s</font><font color="#007700">);<br /> </font><font color="#0000BB">fclose</font><font color="#007700">(</font><font color="#0000BB">$fp</font><font color="#007700">);<br /><br /></font><font color="#FF8000">// page2.php:<br /> <br /> // this is needed for the unserialize to work properly.<br /> </font><font color="#007700">include(</font><font color="#DD0000">"classa.inc"</font><font color="#007700">);<br /><br /> </font><font color="#0000BB">$s </font><font color="#007700">= </font><font color="#0000BB">implode</font><font color="#007700">(</font><font color="#DD0000">""</font><font color="#007700">, @</font><font color="#0000BB">file</font><font color="#007700">(</font><font color="#DD0000">"store"</font><font color="#007700">));<br /> </font><font color="#0000BB">$a </font><font color="#007700">= </font><font color="#0000BB">unserialize</font><font color="#007700">(</font><font color="#0000BB">$s</font><font color="#007700">);<br /><br /> </font><font color="#FF8000">// now use the function show_one() of the $a object. <br /> </font><font color="#0000BB">$a</font><font color="#007700">-></font><font color="#0000BB">show_one</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
></P
></DIV
><P
> If you are using sessions and use <A
HREF="function.session-register.html"
><B
CLASS="function"
>session_register()</B
></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
> 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
<VAR
CLASS="literal"
>stdClass</VAR
> without any functions available
at all, that is, it will become quite useless.
</P
><P
> So if in the example above <VAR
CLASS="varname"
>$a</VAR
> became part of a session
by running <VAR
CLASS="literal"
>session_register("a")</VAR
>, you should include the
file <VAR
CLASS="literal"
>classa.inc</VAR
> on all of your pages, not only page1.php
and page2.php.
</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="keyword.parent.html"
ACCESSKEY="P"
>Terug</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Begin</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="language.oop.magic-functions.html"
ACCESSKEY="N"
>Volgende</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><VAR
CLASS="literal"
>parent</VAR
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="language.oop.html"
ACCESSKEY="U"
>Omhoog</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>The magic functions <VAR
CLASS="literal"
>__sleep</VAR
> and <VAR
CLASS="literal"
>__wakeup</VAR
></TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
