DBI.html

[%#
  # IMPORTANT NOTE
  #   This documentation is generated automatically from source
  #   templates.  Any changes you make here may be lost.
  # 
  #   The 'docsrc' documentation source bundle is available for download
  #   from http://www.template-toolkit.org/docs.html and contains all
  #   the source templates, XML files, scripts, etc., from which the
  #   documentation for the Template Toolkit is built.
-%]
[% META book = 'Modules'
        page = 'Plugin_DBI'
%]
[%  WRAPPER toc;
	INCLUDE tocitem title="SYNOPSIS";
	INCLUDE tocitem title="DESCRIPTION";
	INCLUDE tocitem title="OBJECT METHODS"
                         subs=["connect($data_source, $username, $password)", "query($sql)", "prepare($sql)", "execute(@args)", "do($sql)", "quote($value, $type)", "disconnect()"];
	INCLUDE tocitem title="PRE-REQUISITES";
	INCLUDE tocitem title="AUTHORS";
	INCLUDE tocitem title="VERSION";
	INCLUDE tocitem title="HISTORY";
	INCLUDE tocitem title="COPYRIGHT";
	INCLUDE tocitem title="SEE ALSO";
    END
%]
<!-- Pod to HTML conversion by the Template Toolkit version 2 -->
[% WRAPPER section
    title="SYNOPSIS"
-%]<pre>    # use positional arguments...
    [% tt_start_tag %] USE DBI('dbi:driver:database', 'username', 'password') [% tt_end_tag %]</pre>
<pre>    # ...or named parameters...
    [% tt_start_tag %] USE DBI(data_source = 'dbi:driver:database',
               username    = 'username', 
               password    = 'password') [% tt_end_tag %]</pre>
<pre>    # ...or call connect() explicitly
    [% tt_start_tag %] USE DBI [% tt_end_tag %]
    [% tt_start_tag %] DBI.connect(dsn, user, pass) [% tt_end_tag %]</pre>
<pre>    # Or don't connect at all, and when necessary DBI will connect
    # automatically using the environment variable DBI_DSN. See below.</pre>
<pre>    [% tt_start_tag %] FOREACH item = DBI.query( 'SELECT rows FROM table' ) [% tt_end_tag %]
       Here's some row data: [% tt_start_tag %] item.field [% tt_end_tag %]
    [% tt_start_tag %] END [% tt_end_tag %]</pre>
<pre>    [% tt_start_tag %] query = DBI.prepare('SELECT * FROM user WHERE manager = ?') [% tt_end_tag %]
    [% tt_start_tag %] FOREACH user = query.execute('sam') [% tt_end_tag %]
       ...
    [% tt_start_tag %] FOREACH user = query.execute('abw') [% tt_end_tag %]
       ...</pre>
<pre>    [% tt_start_tag %] IF DBI.do(&quot;DELETE FROM users WHERE uid = 'sam'&quot;) [% tt_end_tag %]
       Oh No!  The user was deleted!
    [% tt_start_tag %] END [% tt_end_tag %]</pre>
[%- END %]
[% WRAPPER section
    title="DESCRIPTION"
-%]<p>
This Template Toolkit plugin module provides an interface to the Perl
DBI/DBD modules, allowing you to integrate SQL queries into your template
documents.
</p>
<p>
A DBI plugin object can be created as follows:
</p>
<pre>    [% tt_start_tag %] USE DBI [% tt_end_tag %]</pre>
<p>
This creates an uninitialised DBI object.  You can then open a connection
to a database using the connect() method.
</p>
<pre>    [% tt_start_tag %] DBI.connect('dbi:driver:database', 'username', 'password') [% tt_end_tag %]</pre>
<p>
The DBI connection can be opened when the plugin is created by passing
arguments to the constructor, called from the USE directive.
</p>
<pre>    [% tt_start_tag %] USE DBI('dbi:driver:database', 'username', 'password') [% tt_end_tag %]</pre>
<p>
You can also use named parameters to provide the data source connection 
string, user name and password.
</p>
<pre>    [% tt_start_tag %] USE DBI(data_source =&gt; 'dbi:driver:database',
               username    =&gt; 'username',
               password    =&gt; 'password')  [% tt_end_tag %]</pre>
<p>
Lazy Template hackers may prefer to use 'dsn' or 'connect' as a shorthand
form of the 'data_source' parameter, and 'user' and 'pass' as shorthand
forms of 'username' and 'password', respectively.
</p>
<pre>    [% tt_start_tag %] USE DBI(connect =&gt; 'dbi:driver:database',
               user    =&gt; 'username',
               pass    =&gt; 'password')  [% tt_end_tag %]</pre>
<p>
Any additional DBI attributes can be specified as named parameters.
The 'PrintError' attribute defaults to 0 unless explicitly set true.
</p>
<pre>    [% tt_start_tag %] USE DBI(dsn, user, pass, ChopBlanks=1) [% tt_end_tag %]</pre>
<p>
The DBI connect_cached() method is used instead of the connect()
method.  This allows for connection caching in a server environment,
such as when the Template Toolkit is used from an Apache mod_perl
handler.   In such a case, simply enable the mod_env module and put in a
line such as:
</p>
<p>
SetEnv DBI_DSN &quot;dbi:DBDriver:DBName;host=DBHost;user=User;password=Password&quot;
</p>
<p>
Then use the DBI plugin without any parameters and without calling connect.
</p>
<p>
Methods can then be called on the plugin object using the familiar dotted
notation:
</p>
<pre>    [% tt_start_tag %] FOREACH item = DBI.query( 'SELECT rows FROM table' ) [% tt_end_tag %]
       Here's some row data: [% tt_start_tag %] item.field [% tt_end_tag %]
    [% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
See [% ttlink('OBJECT METHODS') -%] below for further details of the methods available.
</p>
<p>
An alternate variable name can be provided for the plugin as per regular
Template Toolkit syntax:
</p>
<pre>    [% tt_start_tag %] USE mydb = DBI('dbi:driver:database','username','password') [% tt_end_tag %]</pre>
<pre>    [% tt_start_tag %] FOREACH item = mydb.query( 'SELECT rows FROM table' ) [% tt_end_tag %]
       ...</pre>
<p>
You can also specify the DBI plugin name in lower case if you prefer:
</p>
<pre>    [% tt_start_tag %] USE dbi(dsn, user, pass) [% tt_end_tag %]
    [% tt_start_tag %] FOREACH item = dbi.query( 'SELECT rows FROM table' ) [% tt_end_tag %]
       ...</pre>
<p>
The disconnect() method can be called to explicitly disconnect the
current database, but this generally shouldn't be necessary as it is
called automatically when the plugin goes out of scope.  You can call
connect() at any time to open a connection to another database.  The
previous connection will be closed automatically.
</p>
[%- END %]
[% WRAPPER section
    title="OBJECT METHODS"
-%][% WRAPPER subsection
   title = "connect($data_source, $username, $password)"
-%]<p>
Establishes a database connection.  This method accepts both positional 
and named parameter syntax.  e.g. 
</p>
<pre>    [% tt_start_tag %] DBI.connect(data_source, username, password) [% tt_end_tag %]
    [% tt_start_tag %] DBI.connect(data_source = 'dbi:driver:database'
                   username    = 'foo' 
                   password    = 'bar' ) [% tt_end_tag %]</pre>
<p>
The connect method allows you to connect to a data source explicitly.
It can also be used to reconnect an exisiting object to a different
data source.
</p>
[%- END %]
[% WRAPPER subsection
   title = "query($sql)"
-%]<p>
This method submits an SQL query to the database and creates an iterator 
object to return the results.  This may be used directly in a FOREACH 
directive as shown below.  Data is automatically fetched a row at a time
from the query result set as required for memory efficiency.
</p>
<pre>    [% tt_start_tag %] FOREACH row = DBI.query('select * from users') [% tt_end_tag %]
       Each [% tt_start_tag %] row.whatever [% tt_end_tag %] can be processed here
    [% tt_start_tag %] END [% tt_end_tag %]</pre>
[%- END %]
[% WRAPPER subsection
   title = "prepare($sql)"
-%]<p>
Prepare a query for later execution.  This returns a compiled query
object (of the Template::Plugin::DBI::Query class) on which the
execute() method can subsequently be called.
</p>
<pre>    [% tt_start_tag %] query = DBI.prepare('SELECT * FROM users WHERE id = ?') [% tt_end_tag %]</pre>
[%- END %]
[% WRAPPER subsection
   title = "execute(@args)"
-%]<p>
Execute a previously prepared query.  This method should be called on
the query object returned by the prepare() method.  Returns an
iterator object which can be used directly in a FOREACH directive.
</p>
<pre>    [% tt_start_tag %] query = DBI.prepare('SELECT * FROM users WHERE manager = ?') [% tt_end_tag %]</pre>
<pre>    [% tt_start_tag %] FOREACH user = query.execute('sam') [% tt_end_tag %]
       [% tt_start_tag %] user.name [% tt_end_tag %]
    [% tt_start_tag %] END [% tt_end_tag %]</pre>
<pre>    [% tt_start_tag %] FOREACH user = query.execute('sam') [% tt_end_tag %]
       [% tt_start_tag %] user.name [% tt_end_tag %]
    [% tt_start_tag %] END [% tt_end_tag %]</pre>
[%- END %]
[% WRAPPER subsection
   title = "do($sql)"
-%]<p>
The do() method executes a sql statement from which no records are
returned.  It will return true if the statement was successful
</p>
<pre>    [% tt_start_tag %] IF DBI.do(&quot;DELETE FROM users WHERE uid = 'sam'&quot;) [% tt_end_tag %]
       The user was successfully deleted.
    [% tt_start_tag %] END [% tt_end_tag %]</pre>
[%- END %]
[% WRAPPER subsection
   title = "quote($value, $type)"
-%]<p>
Calls the quote() method on the underlying DBI handle to quote the value
specified in the appropriate manner for its type.
</p>
[%- END %]
[% WRAPPER subsection
   title = "disconnect()"
-%]<p>
Disconnects the current database.
</p>
[%- END %]
[%- END %]
[% WRAPPER section
    title="PRE-REQUISITES"
-%]<p>
Perl 5.005, Template-Toolkit 2.00, DBI 1.02
</p>
[%- END %]
[% WRAPPER section
    title="AUTHORS"
-%]<p>
The DBI plugin was written by Simon A Matthews,
&lt;sam@knowledgepool.com&gt;, with contributions from Andy Wardley
&lt;abw@kfs.org&gt;.
</p>
[%- END %]
[% WRAPPER section
    title="VERSION"
-%]<p>
1.04, distributed as part of the
Template Toolkit version 2.04, released on 27 June 2001.
</p>
[%- END %]
[% WRAPPER section
    title="HISTORY"
-%]
<ul>

<li><b>1.04  2001/04/06  abw</b><br>
<p>
Removed duplicated $VERSION number.
</p>


<li><b>1.03  2000/11/31  sam</b><br>
<p>
Added _connect method to Plugin::DBI for backwards compatability with code 
from version 1 of Template that subclassed the plugin
</p>
<p>
Changed the new method on the DBI plugin so that it checks to see if it is
being called by a subclassed object.  
</p>
<p>
Fixed the return value in the DBI plugin when connect is called more than
once in the lifetime of the plugin.
</p>


<li><b>1.02  2000/11/14  abw</b><br>
<p>
Added prev() and next() methods to Template::Plugin::DBI:Iterator to
return the previous and next items in the iteration set or undef if
not available.
</p>


<li><b>1.01  2000/11/03  abw</b><br>
<p>
Modified connect method to pass all named arguments to DBI.  e.g.
</p>
<pre>    [% tt_start_tag %] USE DBI(dsn, user, pass, ChopBlanks=1) [% tt_end_tag %]</pre>

</ul>
[%- END %]
[% WRAPPER section
    title="COPYRIGHT"
-%]<p>
Copyright (C) 1999-2000 Simon Matthews.  All Rights Reserved
</p>
<p>
This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
</p>
[%- END %]
[% WRAPPER section
    title="SEE ALSO"
-%]<p>
[% ttlink('Template::Plugin', 'Template::Plugin') -%], [% ttlink('CPAN::DBI', 'CPAN::DBI') -%]
</p>
[%- END %]