= Split domain file =

[wiki:gmf:gmf <back]

Scenario: Root element {{{A}}} contains element {{{B}}} and element {{{C}}}.  Element {{{C}}} is to be saved in a separate domain file.

Solution:
  - Create an element {{{CReference}}}.
  - {{{CReference}}} contains an element {{{C}}} with {{{containment=false}}}.
  - Override method {{{doDefaultElementCreation()}}} in class {{{CReferenceCreateCommand}}}. This method contains the creation of the corresponding element {{{C}}}, similar to the following:
{{{
// create CReference-Object
EObject cReference = super.doDefaultElementCreation();

// get resource of root element A
Resource aResource = getElementToEdit().eResource();

// create C object
C c = ExampleFactory.eINSTANCE.createC();

// add c to cReference
((CReference)cReference).setC(c);

// create model file for C
File cFile = new File(pathToCFile);
if (!cFile.exists())
   try {
	cFile.createNewFile();
   } catch (IOException e) {
	// TODO Auto-generated catch block
	e.printStackTrace();
   }

// create resource for c
Resource cResource = aResource.getResourceSet().createResource(
	URI.createFileURI(cFile.getAbsolutePath()));

// add c to new cResource
cResource.getContents().add(c);

// save resource; this is only needed, if you reduce the save command of the generated editor that it does not save all resources
try {
   cResource.save(ExampleDiagramEditorUtil.getSaveOptions());
} catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
}
}}}

  - The last step is to update the modification stamp of the {{{ResourceSetInfo}}}. This is an inner class of your {{{XXXDocumentProvider}}}. If you don't update the modification stamp, you get an error similar to "The file has been changed on the file system" when you save your diagram. Modify the method {{{notifyChanged}}} of class {{{ResourceSetModificationListener}}} (inner class of {{{XXXDocumentProvider}}}):
{{{
if (!notification.isTouch()
   && myModifiedFilter.matches(notification)) {
   // Update modification stamp if new Resource was added to ResourceSet
   if (notification.getNotifier() instanceof ResourceSet) {
	if (notification.getEventType() == Notification.ADD) {
	   myInfo.setModificationStamp(computeModificationStamp(myInfo));
	}
   }
   // ...
}
}}}