#29801 closed New feature (duplicate)
Allow using fixtures in data migrations
Reported by: | Calvin DeBoer | Owned by: | nobody |
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Component: | Migrations | Version: | dev |
Severity: | Normal | Keywords: | environments migrations |
Cc: | Alex Dehnert | Triage Stage: | Unreviewed |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description (last modified by )
Background
Django's current recommendation for adding data to a application is through the well documented "DataMigration" via RunSQL
and RunPython
calls. This represents an improvement over the fixture loading for a variety of reasons (it doesn't force developers to keep their fixtures up to date, control over overwriting data ,etc). Fixtures would be great if they didn't have to be kept up to date with the DB's current state (more on that later). As the applications we've been building with Django have grown in complexity we've seen an increase in the need to have control over which data is created in different application environments. For example, in production we want to add a large dataset foo
(production data), but in development we only want to load a smaller dataset bar
(for Developer Experience); furthermore, in tests we don't want to add ANY data because we want the tests, setUp
method to granularly control what data is available in the DB with that set of tests. For the test piece, we investigated setting the MIGRATION_MODULES
setting to None for all the apps in a test_settings
file, but that seemed heavy handed, and also only handled a single application environment.
Suggestion
- add a method called
loaddata
that takes a fixture andapps
<- (the model context within a migration from which one can obtain aFakeModel
instance representing the Model at state of that migration.
import os from django.db import migrations import environize PATH = 'path/to/fixtures/' def load_fixture(apps, schema_editor): fixture_file = os.path.join(PATH, 'myfixture.json') environize.loaddata(apps, fixture_file) class Migration(migrations.Migration): dependencies = [ ('app', '0003_auto_20180916_1122'), ] operations = [ migrations.RunPython(load_fixture, lambda x, y: None) ]
- allow
RunPython
andRunSQL
to take an additional keyword that will tell django which envs to include or exclude in aDataMigration
.
class Migration(migrations.Migration): dependencies = [ ('app', '0002_auto_20180916_1122'), ] operations = [ migrations.RunPython(add_prod_data, remove_hams, only_in=['production']), migrations.RunSQL("INSERT blah;", "REMOVE blah;", except_in=['test']) ]
Implementation
https://github.com/cgdeboer/environize
Here is a hastily put together library to allow environments inside migrations and have state specific loaddata
. The environment stuff is implemented as decorators on the function at the moment, probably makes more sense to just inherit RunPython
and RunSQL
and provide the keywords shows above in example 2.
Probably makes the most sense to continue to develop this as a package outside of Django, but before I do that, thought I'd see if there is any appetite for it in core django.
Change History (5)
comment:1 by , 6 years ago
Description: | modified (diff) |
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comment:2 by , 6 years ago
Resolution: | → duplicate |
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Status: | new → closed |
Summary: | Feature Suggestion for Migrations → Allow using fixtures in data migrations |
comment:3 by , 6 years ago
Is there another ticket to reference for the bit in the description about excluding certain environments for various DataMigration operations ? The duplicate ticket was just for loading fixture data in migrations.
comment:4 by , 6 years ago
Sorry, I don't need that far. I'm not immediately convinced something like that is needed as I think you should be able to whatever Python conditions you like to conditionally add operations to Migration.operations
.
comment:5 by , 3 years ago
Cc: | added |
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Duplicate of #24778.