1 files changed, 187 insertions, 0 deletions
diff --git a/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/ChildDataSource.java b/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/ChildDataSource.java
new file mode 100644
index 0000000..8123668
--- /dev/null
+++ b/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/ChildDataSource.java
@@ -0,0 +1,187 @@
+package net.wotonomy.control;
+
+import java.util.Collection;
+import java.util.Iterator;
+
+import net.wotonomy.foundation.NSArray;
+import net.wotonomy.foundation.NSMutableArray;
+
+/**
+* A data source that automates the process of 
+* creating a child editing context and copying
+* objects from a parent context into it. 
+* Attach this data source to a display group
+* that represents a "detail" or "drill-down" 
+* view. <br><br>
+* 
+* Once created, editingContext() will return the 
+* child context, and fetch() will return the objects 
+* that were copied into the child context.
+*/
+public class ChildDataSource extends EODataSource
+{
+    private EODataSource parent;
+    private EOEditingContext context;
+    private EOClassDescription classDescription;
+    private NSMutableArray objects;
+    
+    /**
+    * Creates a child editing context for the
+    * specified parent's context and copies the 
+    * specified object into the child context.
+    * The object must exist in the parent context.
+    * fetch() will return the child's object.
+    */
+	public ChildDataSource( 
+        EODataSource aParentSource,
+        Object anObject )
+	{
+        this( aParentSource, new NSArray( (Object) anObject ) );
+	}
+    
+    /**
+    * Creates a child editing context for the
+    * specified parent's context and copies the 
+    * specified objects into the child context.
+    * The objects must exist in the parent context.
+    * The order of the parent's objects in the
+    * collection will determine the order in 
+    * which the child objects are returned from 
+    * fetch().
+    */
+	public ChildDataSource( 
+        EODataSource aParentSource,
+        Collection anObjectList )
+	{
+        EOEditingContext parentContext = 
+            aParentSource.editingContext();
+
+        parent = aParentSource;
+        context = new EOEditingContext( parentContext );
+//!new net.wotonomy.ui.swing.util.ObjectInspector( context );        
+        objects = new NSMutableArray();
+        classDescription = null;
+
+        Object o;        
+        Object copy;
+        boolean allSameClass = true;
+        Iterator it = anObjectList.iterator();
+        while ( it.hasNext() )
+        {
+            o = it.next();
+            
+            // determine class
+            if ( allSameClass == true )
+            {
+                Class c = o.getClass();
+                if ( classDescription == null ) 
+                {
+                    classDescription = 
+                        EOClassDescription.classDescriptionForClass( c );   
+                }
+                else
+                {
+                    if ( c != classDescription.getDescribedClass() )
+                    {
+                        allSameClass = false;  
+                        classDescription = null;
+                    }
+                }
+            }
+            
+            // copy and add to list
+            objects.addObject( parentContext.faultForGlobalID(
+                parentContext.globalIDForObject( o ), context ) );
+        }
+	}
+    
+    /**
+    * Returns the editing context for this data source,
+    * which was created in the constructor and whose 
+    * parent is the editing context specified in the
+    * constructor.
+    */
+    public EOEditingContext editingContext()
+    {
+        return context;
+    }
+	
+    /**
+    * This implementation does nothing.
+    */
+    public void insertObject ( Object anObject )
+	{
+
+	}
+
+    /**
+    * This implementation does nothing.
+    */
+    public void deleteObject ( Object anObject )
+	{
+
+	}
+
+    /**
+    * Returns a List containing the objects in this
+    * data source.  This implementation returns all
+	* TestObjects that have been persisted to the 
+	* datastore in the data directory.
+    */
+    public NSArray fetchObjects ()
+    {
+        return new NSArray( (Collection) objects );
+    }
+
+    /**
+    * Returns a data source that is capable of
+    * manipulating objects of the type returned by 
+    * applying the specified key to objects 
+    * vended by this data source.
+    * This implementation forwards the call to
+    * the parent data source.
+    * @see #qualifyWithRelationshipKey
+    */
+    public EODataSource 
+        dataSourceQualifiedByKey ( String aKey )
+	{
+        //FIXME: This is fundamentally broken.
+        // Objects vended from the returned source
+        // are not registered in our editing context.
+        // We probably need yet another utility data
+        // source class that would wrap another source
+        // and convert vended objects into a different
+        // context.
+        
+        return parent.dataSourceQualifiedByKey( aKey );
+	}
+
+    /**
+    * Restricts this data source to vend those 
+    * objects that are associated with the specified 
+    * key on the specified object.
+    * This implementation forwards the call to
+    * the parent data source.
+    */
+    public void 
+        qualifyWithRelationshipKey ( 
+        String aKey, Object anObject )
+	{
+		parent.qualifyWithRelationshipKey( aKey, anObject );	
+	}
+
+    /**
+    * Returns the description of the class of the
+    * objects that is vended by this data source,
+    * or null if this cannot be determined.
+	* This implementation returns the class of the
+    * objects passed to the constructor if they are
+    * all the same class, otherwise returns null.
+    */
+    public EOClassDescription
+        classDescriptionForObjects ()
+    {
+        return classDescription;
+    }
+
+}