Check, using name, if a collection exists in blend & is linked to scene

Question

I have a script that creates a new collection but if I run it again it adds a new collection named "Personal Collection.001" and so on, what I would like to tell to the script is that if that collection name is in the scene then don't make a new one.

import bpy

myCol = bpy.data.collections.new('Personal collection')
bpy.context.scene.collection.children.link(myCol) #Creates a new collection


for myCol in bpy.data.collections:
    if myCol.name == "Personal Collection":
        print ("Collection found in scene")

Cheers, Juan

Answer 1

you can do it like this:

import bpy


collectionFound = False

print("START **************")

for myCol in bpy.data.collections:
    print(myCol.name)
    if myCol.name == "Personal Collection":
        collectionFound = True
        print ("Collection found in scene")
        break
        
        
if collectionFound == False:
    myCol = bpy.data.collections.new("Personal Collection")
    bpy.context.scene.collection.children.link(myCol) #Creates a new collection
    print("created")
else:
    print("exists already")

and be careful: you mismatched upper- and lowercase!! String comparison is case sensitive.

Answer 2

Check it exists and is linked to scene.

IMO Two tests required here, one to test if collection exists, and secondly if it is linked at any level to the current scene. A quick test for the latter is to see if the scene is a user of the collection.

import bpy
context = bpy.context

# name of collection
name = "Foo"

scene = context.scene

coll = bpy.data.collections.get(name)
# if it doesn't exist create it
if coll is None:
    coll = bpy.data.collections.new(name)
# if it is not linked to scene colleciton treelink it
if not scene.user_of_id(coll):
    context.collection.children.link(coll)

Related

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