How to get all collections of the current scene?

Question

I'd like to get all collections in the current scene and can't find a way to do that. I found bpy.data.collections to get all collections stored in the blend and C.scene.collection.children to return the first level of sub-collections. However, I can't find out which collection is linked to each scene. I wonder if there is a simple way like iterating through the objects in context C.scene.objects?

Q: How to get all collections of the current scene?

Answer 1

Recursively walk the tree.

Similarly to https://blender.stackexchange.com/a/137866/15543 and Sorting Collections Alphabetically in the Outliner

import bpy

def traverse_tree(t):
    yield t
    for child in t.children:
        yield from traverse_tree(child)

coll = bpy.context.scene.collection

for c in traverse_tree(coll):
    print(c.name)

Look at ID users

It is most likely a lot quicker to run over the collections and check if they are in use by the scene. If a collection is linked anywhere in the hierarchy of a scene's collection tree, then the scene is a user of the collection.

>>> collections_in_scene = [
        c for c in D.collections 
        if C.scene.user_of_id(c)
    ]
>>> collections_in_scene
[bpy.data.collections['Collection 1'], bpy.data.collections['Collection 1 1'], bpy.data.collections['Collection 1 1 1']]