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<?xml version="1.0"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
<chapter id="migration-1">
<title>Migration from 1.X versions</title>
<sect1><title>GdaValue and GdaDataModel changes</title>
<para>Libgda values were stored in <classname>GdaValue</classname> structures, this is no longer the case
as the standard <classname>GValue</classname> container is now used. As a consequence data types are now
identified by their <classname>GType</classname> identifier, there is thus no more any
<classname>GdaType</classname> definition.</para>
<para>The <classname>GdaDataModel</classname> has been transformed into an interface (as defined by the Glib
object system), and the old <classname>GdaDataModel</classname> has been replaced by the
<classname>GdaDataModelRow</classname> class. No code using the <classname>GdaDataModel</classname> should
assume that data is internally stored as rows (vectors) of values as it was the case in the previous
stable release.
</para>
<para>In the new version, many objects implement the
<classname>GdaDataModel</classname> interface for various usages which did not exist in the previous version
such as data import and filtering. <classname>GdaDataModel</classname> objects should now be considered
as non writable, and if they need to be modified, the modifications permissions should be checked
using the <function>gda_data_model_get_attributes_at()</function> function. See the
<link linkend="datamodels">section about the various data models</link> for more information.
</para>
<para> The following UML schema shows the various implementations of the <classname>GdaDataModel</classname>
interface and what they are for. Note that the
<classname>GdaDataModelRow</classname> should not be instantiated directly but either
used as a base class, or used through its children classes.
</para>
<para>
<mediaobject>
<imageobject role="html">
<imagedata fileref="DataModels.png" format="PNG"/>
</imageobject>
<textobject>
<phrase>Various implementations of the GdaDataModel interface</phrase>
</textobject>
</mediaobject>
</para>
</sect1>
<sect1><title>GdaClient, GdaConnection and GdaError</title>
<para>The <classname>GdaClient</classname> usage has remained unchanged except for some small API alterations and
a specific API has been defined to create and destroy databases.</para>
<para>The <classname>GdaError</classname> class has been renamed to <classname>GdaConnectionEvent</classname> and
can now convey not only errors but also other kind of events which have happened on a connection</para>
<para>The <classname>GdaConnection</classname> usage has remained by far unchanged, but some of its API have had
some alterations (finding the equivalent is trivial). The most noticeable change being that
the <function>gda_connection_escape_string()</function> has been removed because string escaping is
now done by a <classname>GdaDataHandler</classname> object which each
<classname>GdaServerProvider</classname> provides for each data type.
</para>
</sect1>
<sect1><title>Various API changes</title>
<para>
<itemizedlist>
<listitem>
<para><classname>GdaFieldAttributes</classname> has been renamed <classname>GdaColumn</classname></para>
</listitem>
<listitem>
<para>The <classname>GdaParameter</classname> is now an object, and it is extensively used within
<classname>GdaParameterList</classname> objects. Each <classname>GdaParameterList</classname> object represent a
vector of parameters (which may or may not have values assigned) and is the base of the
<classname>GdaDataModelIter</classname> iterator object. The <classname>GdaParameter</classname> API has been
altered.</para>
</listitem>
<listitem>
<para>The <classname>GdaExport</classname> class has been removed, the features it offered are now implemented
in each <classname>GdaDataModel</classname> object.</para>
</listitem>
<listitem>
<para><classname>GdaSelect</classname> has been renamed
<classname>GdaDataModelFilterSQL</classname></para>
</listitem>
<listitem>
<para>The <classname>GdaTable</classname> class has been replaced by the
<classname>GdaDataModelQuery</classname> class: it's a data model which can refresh itself and can be
configured to be updatable, it's not limited to a database table.</para>
</listitem>
<listitem>
<para>The <classname>GdaXmlDatabase</classname> has been removed and the default database is now SQLite
which is a complete RDBMS in a file</para>
</listitem>
<listitem>
<para>All the <function>gda_xql_*()</function> functions have been removed because they were unused and unmaintained.
</para>
</listitem>
<listitem>
<para>The 'xml' provider has been removed as it did not work correctly and has been replaced by the SQLite provider
as the provider to have serverless databases.</para>
</listitem>
</itemizedlist>
</para>
</sect1>
</chapter>
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