Spring/spring-data-neo4j
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Updated docs on NodeTypeStrategy.

Browse Source
This commit is contained in:
David Montag
2011-03-21 14:45:37 -07:00
parent f7453c2f96
commit 9abbcc2949
1 changed files with 34 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

44
src/docbkx/reference/programming-model/nodetypestrategy.xml
View File

@@ -4,20 +4,44 @@
<title>Reified types for entities</title>
<para>
There are several ways to represent the Java type hierarchy of the data model in the graph. In general for all
node and relationship entities type information is needed to perform certain repository operations. That's
why the hierarchy up to <code>java.lang.Object</code> of all these classes will be persisted in the graph.
Implementations of NodeTypeStrategy take care of persisting this information on entity instance
node and relationship entities type information is needed to perform certain repository operations. Some of
this type information is saved in the graph database.
</para>
<para>
Implementations of <code>NodeTypeStrategy</code> take care of persisting this information on entity instance
creation. They also provide the repository methods that use this type information to perform their operations
like findAll, count etc.
like findAll, count, etc.
</para>
<para>
The current implementation uses nodes to represent the Java type hierarchy which are connected via SUBCLASS_OF
relationships to their superclass nodes and via INSTANCE_OF relationships to the concrete node entity
instance node.
There are three available implementations to choose from.
<itemizedlist>
<listitem>
<para><code>SubReferenceNodeTypeStrategy</code></para>
<para>
Stores entity types in a tree in the graph representing the type hierarchy. Each entity
has a INSTANCE_OF relationship to a type node representing that entity's type. The type may or
may not have a SUBCLASS_OF relationship to another type node.
</para>
</listitem>
<listitem>
<para><code>IndexingNodeTypeStrategy</code></para>
<para>
Stores entity types in the integrated index. Each entity node gets indexed with its type and
any supertypes that are also <code>@NodeEntity</code>-annotated. The special index used for this
is called <code>__types__</code>. Additionally, in order to get the type of an entity node, each
node has a property <code>__type__</code> with the type of that entity.
</para>
</listitem>
<listitem>
<para><code>NoopNodeTypeStrategy</code></para>
<para>
Does not store any type information, and does hence not support finding by type, counting by type,
or retrieving the type of any entity.
</para>
</listitem>
</itemizedlist>
</para>
<para>
An alternative approach could use indexing operations to perform the same functionality. Or one could skip the
NodeTypeStrategy altogether if no strict checks on type conformity are needed, which would allow for a much
more flexible data model.
The default implementation is <code>SubReferenceNodeTypeStrategy</code>.
</para>
</section>