#28073: RemoveField.state_forwards() crashes with AttributeError: 'NoneType'
object
has no attribute 'is_relation'
---------------------------------+-------------------------------------
Reporter: Logan Gunthorpe | Owner: nobody
Type: Bug | Status: closed
Component: Migrations | Version: 1.11
Severity: Normal | Resolution: needsinfo
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
---------------------------------+-------------------------------------
Comment (by Matthew Dennis):
Ive managed to run into this as well on Django 1.11.
I had merged 2 very diverged branches(git) which had conflicting
migrations that couldn't be merged. I deleted 2 leaf migrations that had
been made on the branch and was just going to run make migrate to create
only the fields that were different. I guess you can't do that. Anyway
long story short I never committed the merge and reset my head but this
error persists even after the fact. I'm assuming its something to do with
it thinking I'm at a point that I'm not/doesn't exist.
I can't give you guys solid re-creation steps(and I don't know a lot about
migrations) to get to this point so I'm not asking for a fix here.
But if you're setting a variable to None and then populating it
conditionally in a loop it shouldn't be assumed it will have a value once
the loop is complete. I'm suggesting an assert or some sort of exception
handling for this. Perhaps with a message suggesting they report their
steps to create this scenario on here.
Seeing as the comment above implies that `old_field is None or ...` would
be a valid solution I don't see why you wouldn't just put that in. Adding
that to my local file allows me to proceed but because I don't know whats
causing this I can't merge this branch for fear of breaking it for others.
Thanks
--
Ticket URL: <https://code.djangoproject.com/ticket/28073#comment:7>
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