Why is "Copy Data Path" path different from the tooltip's path?

Question

Why is it that when I right click on a data field and click "Copy Data Path" and paste, it will paste something like this (example: the "Start Frame" of a VSE strip):

sequence_editor.sequences_all["roomWalls01.001"].frame_start

But the tooltip that can be seen when hovering over the same field shows a longer data path:

bpy.data.scenes["Scene"].sequence_editor.sequences_all["roomWalls01.001"].frame_start

"Copy Data Path" leaves off the first part: bpy.data.scenes["Scene"].

Why does it leave that off? Isn't that part usually necessary when making scripts?

I'm very new to Blender Python scripting but I've tried some scripts and I often end up typing the first part out by hand, which seems like an unnecessary hassle.

I theorize that this has something to do with the fact that many Blender Python scripts start out defining variables like these:

context = bpy.context

scene = context.scene

sequences = scene.sequence_editor.sequences_all

But I don't know how I'm supposed to know what kind of variable like that I will have to define first.

I would just like to know why this is. It seems like it probably makes sense, and I'm just using a bad Python workflow or approach. Any explanations? Thank you.

Answer 1

Copy Data Path

From https://www.blender.org/api/blender_python_api_2_77_release/bpy.types.bpy_struct.html?highlight=id_data#bpy.types.bpy_struct.id_data

Note that when keying data paths which contain nested properties this must be done from the ID subclass, in this case the Armature rather than the bone.

Or in the case you pointed out from the scene rather than the strip.

To explain using the console, I have a vid seq called blackfoot, it tells me its id_data is the scene. (The bit you mentioned as "left out")

>>> C.scene.sequence_editor.sequences_all['blackfoot'].id_data
bpy.data.scenes['Scene']

Ok now look at frame_start property

>>> C.scene.sequence_editor.sequences_all['blackfoot'].frame_start
1

>>> C.scene.sequence_editor.sequences_all['blackfoot'].path_resolve('frame_start')
1

>>> C.scene.sequence_editor.sequences_all['blackfoot'].path_from_id('frame_start')
'sequence_editor.sequences_all["blackfoot"].frame_start'

The last one looks familiar, it's what you get when you copy data_path, ie the path from the ID data.

Using

context = bpy.context
scene = context.scene
sequences = scene.sequence_editor.sequences_all

is just IMO good coding practice making the code much more readable

sequences['blackfoot'].frame_start = 1

than

bpy.data.scenes['Scene'].sequence_editor.sequences_all['blackfoot'].frame_start = 1

NB. I also use context = bpy.context in test files, to make pasting them into operator or panel code later simple as context is passed by def to just about all methods.