Using custom node group with Python script for Compositor

Question

I have created some custom node groups that use built-in nodes in Cycles Compositor. Now I would like to have another group that make use of these custom groups. I think in the new node group, I would do something similar to

Mygroupnode = nodes.new('somegroupname')

However, what I got is an error saying there was no type called 'somegroupname'. I understand that the position is expected to receive a node type (not name), but I don't know how to retrieve a type of my group node.

PS: There is a type called 'CompositorNodeGroup', but it can only create an 'empty' node where you should do an extra step to link it to a custom group node. But I do not know how to do it in script.

Answer 1

This is done by adding a node group:

group = C.scene.node_tree.nodes.new('CompositorNodeGroup')

... and then adding the custom group as new group's node tree:

group.node_tree = bpy.data.node_groups['somegroupname']