/usr/share/GNUstep/Documentation/GDL2Intro/EODataSource-class.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- (C)

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions. -->
<!-- Created by GNU Texinfo 6.3, http://www.gnu.org/software/texinfo/ -->
<head>
<title>GNUstep Database Library Introduction 0.1: EODataSource class</title>

<meta name="description" content="GNUstep Database Library Introduction 0.1: EODataSource class">
<meta name="keywords" content="GNUstep Database Library Introduction 0.1: EODataSource class">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="Index.html#Index" rel="index" title="Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Classes.html#Classes" rel="up" title="Classes">
<link href="EOEditingContext-class.html#EOEditingContext-class" rel="next" title="EOEditingContext class">
<link href="EOAdaptorChannel-class.html#EOAdaptorChannel-class" rel="prev" title="EOAdaptorChannel class">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {margin-left: 3.2em}
kbd {font-style: oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nolinebreak {white-space: nowrap}
span.roman {font-family: initial; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>


</head>

<body lang="en">
<a name="EODataSource-class"></a>
<div class="header">
<p>
Next: <a href="EOEditingContext-class.html#EOEditingContext-class" accesskey="n" rel="next">EOEditingContext class</a>, Previous: <a href="EOAdaptorChannel-class.html#EOAdaptorChannel-class" accesskey="p" rel="prev">EOAdaptorChannel class</a>, Up: <a href="Classes.html#Classes" accesskey="u" rel="up">Classes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="EODataSource-class-1"></a>
<h2 class="chapter">21 EODataSource class</h2>
<a name="index-class_002c-EODataSource"></a>

<a name="overview-6"></a>
<h3 class="section">21.1 overview</h3>
<p>EODataSource is an abstract base class, and implements no real functionality on its own,
instead you&rsquo;ll access EODataSource subclass.
</p>
<p>A data source represents a collection of rows inside of a table. 
It can create rows, delete and provide access to the individual rows 
represented as Enterprise objects.
</p>
<p>Typical methods for an EODataSource subclass:
</p><ol>
<li> -fetchObjects
</li><li> -createObject:
</li><li> -deleteObject:
</li><li> -insertObject:
</li><li> -dataSourceQualifiedByKey:
</li></ol>

<a name="Fetch-objects"></a>
<h3 class="section">21.2 Fetch objects</h3>
<p>The -fetchObjects method will return an array of enterprise objects.
Typically these will be retrieved directly from data in the database server.
Then the caller will save the array for access or modification.
</p>
<a name="Creating-objects"></a>
<h3 class="section">21.3 Creating objects</h3>
<p>The -createObject: method will create a new enterprise object for insertion into the database.
A subclass will generally insert this new object into an editing context.
Though the caller is responsible for inserting the object into the data source with -insertObject:.
</p>
<a name="Inserting-objects"></a>
<h3 class="section">21.4 Inserting objects</h3>
<p>The -insertObject: method will schedule the object for addition into the database server
EditingContexts changes are saved to the database.
</p>
<a name="Deleting-objects"></a>
<h3 class="section">21.5 Deleting objects</h3>
<p>The -deleteObject: method will schedule the object for removal from the database server
when the EOEditingContexts changes are saved to the database.
</p>
<a name="Qualified-DataSources"></a>
<h3 class="section">21.6 Qualified DataSources</h3>
<p>Subclasses may implement this method to return a detail data source.
</p>
<p>A detail data source is a datasource which is created from following a relationship 
in an object of the receiever: the master object.
</p>
<p>in our example you might have a data source for the authors entity
and qualify a detail data source, with the toBooks key. 
</p>
<a name="EODatabaseDataSource-class"></a>
<h3 class="section">21.7 EODatabaseDataSource class</h3>
<p>EODatabaseDataSource class is a subclass of EODataSource.
</p>
<p>To initialize an EODatabaseDataSource you&rsquo;ll give it a reference to an EOEditingContext
and an entity name.
</p>
<p>EODatabaseDataSource initializers:
</p><ol>
<li> -initWithEditingContext:entityName:
</li><li> -initWithEditingContext:entityName:fetchSpecificationName:
</li></ol>

<p>Once initialized, you can call the EODataSource methods on it, to
create fetch insert, and delete objects from the datasource.
</p>
<hr>
<div class="header">
<p>
Next: <a href="EOEditingContext-class.html#EOEditingContext-class" accesskey="n" rel="next">EOEditingContext class</a>, Previous: <a href="EOAdaptorChannel-class.html#EOAdaptorChannel-class" accesskey="p" rel="prev">EOAdaptorChannel class</a>, Up: <a href="Classes.html#Classes" accesskey="u" rel="up">Classes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
</div>



</body>
</html>
gnustep-dl2 0.12.0-15.1 / usr / share / GNUstep / Documentation / GDL2Intro / EODataSource-class.html
