#24098: Add utility function to mark RunPython operations as noops
-----------------------------+--------------------
Reporter: MarkusH | Owner:
Type: New feature | Status: new
Component: Migrations | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 1 | UI/UX: 0
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When adding a field to a model and propagating new values with a
`RunPython` operation in migrations, there is often no reason for a
backwards function to call. Same goes for the other direction.
However, if no backwards callable is specified, the respective migration
isn't reversible. And the forwards callable is required.
I propose to add a class attribute that effectively provides a no-op but
makes the code a bit more expressive:
{{{#!python
class RunPython(Operation):
# ...
noop = lambda apps, schema_editor: None
}}}
Hence the migration could look like
{{{#!python
from django.db import migrations
def forwards(apps, schema_editor):
# Do some stuff
class Migration(migrations.Migration):
operations = [
# Current way
migrations.RunPython(forwards, lambda apps, schema_editor: None)
# New approach
migrations.RunPython(forwards, migrations.RunPython.noop)
]
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/24098>
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