Changes between Version 14 and Version 15 of PluginDevelopmentGuide

Timestamp:

13.04.2013 16:54:48 (12 years ago)

Author:

jri

Comment:

Writing an imperative migration

PluginDevelopmentGuide

@@ -539 +539 @@
 }}}
 
-As you see, this migration defines 3 topic types (and no other things): the 2 simple types //Title// and //Text//, and the composite type //Note//. A Note is composed of a Title and a Text.
+As you see, this migration defines 3 topic types (and no other things): //Title// and //Text// are 2 simple types, and //Note// is a composite type. A Note is composed of one Title and one Text.
 
 === Writing an imperative migration ===
+
+An imperative migration is a Java class that is derived from `de.deepamehta.core.service.Migration` and that overrides the `run()` method. The `run()` method is called by DeepaMehta to run the migration.
+
+Within the migration you have access to the //DeepaMehta Core Service// through the `dms` object. By the means of the DeepaMehta Core Service you can perform arbitrary database operations. Typically this involves importing further objects from the `de.deepamehta.core` API.
+
+As an example see a migration that comes with the //DeepaMehta 4 Topicmaps// plugin:
+
+{{{
+#!java
+package de.deepamehta.plugins.topicmaps.migrations;
+
+import de.deepamehta.core.TopicType;
+import de.deepamehta.core.model.AssociationDefinitionModel;
+import de.deepamehta.core.service.Migration;
+
+public class Migration3 extends Migration {
+
+    @Override
+    public void run() {
+        TopicType type = dms.getTopicType("dm4.topicmaps.topicmap", null);
+        type.addAssocDef(new AssociationDefinitionModel("dm4.core.composition_def",
+            "dm4.topicmaps.topicmap", "dm4.topicmaps.state", "dm4.core.one", "dm4.core.one"));
+    }
+}
+}}}
+
+Here an association definition is added to the //Topicmap// type subsequently.