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<title>Class: SQLite3::Translator</title>
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<table width="100%" border='0' cellpadding='0' cellspacing='0' class='banner'><tr>
<td class="file-title"><span class="file-title-prefix">Class</span><br />SQLite3::Translator</td>
<td align="right">
<table cellspacing=0 cellpadding=2>
<tr valign="top">
<td>In:</td>
<td>
<a href="../../files/lib/sqlite3/translator_rb.html">lib/sqlite3/translator.rb</a>
</td>
</tr>
<tr>
<td>Parent:</td>
<td>
Object
</td>
</tr>
</table>
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<!-- banner header -->
<div id="bodyContent">
<div id="content">
<div class="description"><p>
The <a href="Translator.html">Translator</a> class encapsulates the logic
and callbacks necessary for converting string data to a value of some
specified type. Every <a href="Database.html">Database</a> instance may
have a <a href="Translator.html">Translator</a> instance, in order to
assist in type translation (Database#type_translation).
</p>
<p>
Further, applications may define their own custom type translation logic by
registering translator blocks with the corresponding database‘s
translator instance (<a
href="Database.html#M000099">Database#translator</a>).
</p>
</div>
<div class="sectiontitle">Methods</div>
<ul>
<li><a href="#M000072">add_translator</a></li>
<li><a href="#M000071">new</a></li>
<li><a href="#M000073">translate</a></li>
</ul>
<div class="sectiontitle">Public Class methods</div>
<div class="method">
<div class="title">
<a name="M000071"></a><b>new</b>()
</div>
<div class="description">
<p>
Create a <a href="Translator.html#M000071">new</a> <a
href="Translator.html">Translator</a> instance. It will be preinitialized
with default translators for most SQL data types.
</p>
</div>
<div class="sourcecode">
<p class="source-link">[ <a href="javascript:toggleSource('M000071_source')" id="l_M000071_source">show source</a> ]</p>
<div id="M000071_source" class="dyn-source">
<pre>
<span class="ruby-comment cmt"># File lib/sqlite3/translator.rb, line 18</span>
18: <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">initialize</span>
19: <span class="ruby-ivar">@translators</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span>( <span class="ruby-identifier">proc</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">type</span>,<span class="ruby-identifier">value</span><span class="ruby-operator">|</span> <span class="ruby-identifier">value</span> } )
20: <span class="ruby-ivar">@type_name_cache</span> = {}
21: <span class="ruby-identifier">register_default_translators</span>
22: <span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div class="sectiontitle">Public Instance methods</div>
<div class="method">
<div class="title">
<a name="M000072"></a><b>add_translator</b>( type ) {|type, value| ...}
</div>
<div class="description">
<p>
Add a <a href="Translator.html#M000071">new</a> translator block, which
will be invoked to process type translations to the given type. The type
should be an SQL datatype, and may include parentheses (i.e.,
"VARCHAR(30)"). However, any parenthetical information is
stripped off and discarded, so type translation decisions are made solely
on the "base" type name.
</p>
<p>
The translator block itself should accept two parameters, "type"
and "value". In this case, the "type" is the full type
name (including parentheses), so the block itself may include logic for
changing how a type is translated based on the additional data. The
"value" parameter is the (string) data to convert.
</p>
<p>
The block should return the translated value.
</p>
</div>
<div class="sourcecode">
<p class="source-link">[ <a href="javascript:toggleSource('M000072_source')" id="l_M000072_source">show source</a> ]</p>
<div id="M000072_source" class="dyn-source">
<pre>
<span class="ruby-comment cmt"># File lib/sqlite3/translator.rb, line 37</span>
37: <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">add_translator</span>( <span class="ruby-identifier">type</span>, <span class="ruby-operator">&</span><span class="ruby-identifier">block</span> ) <span class="ruby-comment cmt"># :yields: type, value</span>
38: <span class="ruby-ivar">@translators</span>[ <span class="ruby-identifier">type_name</span>( <span class="ruby-identifier">type</span> ) ] = <span class="ruby-identifier">block</span>
39: <span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div class="method">
<div class="title">
<a name="M000073"></a><b>translate</b>( type, value )
</div>
<div class="description">
<p>
Translate the given string value to a value of the given type. In the
absense of an installed translator block for the given type, the value
itself is always returned. Further, <tt>nil</tt> values are never
translated, and are always passed straight through regardless of the type
parameter.
</p>
</div>
<div class="sourcecode">
<p class="source-link">[ <a href="javascript:toggleSource('M000073_source')" id="l_M000073_source">show source</a> ]</p>
<div id="M000073_source" class="dyn-source">
<pre>
<span class="ruby-comment cmt"># File lib/sqlite3/translator.rb, line 45</span>
45: <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">translate</span>( <span class="ruby-identifier">type</span>, <span class="ruby-identifier">value</span> )
46: <span class="ruby-keyword kw">unless</span> <span class="ruby-identifier">value</span>.<span class="ruby-identifier">nil?</span>
47: <span class="ruby-ivar">@translators</span>[ <span class="ruby-identifier">type_name</span>( <span class="ruby-identifier">type</span> ) ].<span class="ruby-identifier">call</span>( <span class="ruby-identifier">type</span>, <span class="ruby-identifier">value</span> )
48: <span class="ruby-keyword kw">end</span>
49: <span class="ruby-keyword kw">end</span>
</pre>
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