#25105: Migrating multiple CharFields to null=False breaks on PostgreSQL
----------------------------+------------------------------------
Reporter: danielr | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 1.8
Severity: Normal | Resolution:
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 danielr):
On further investigation, in turns out that a) you do need at least two
fields being migrated, and b) you also need a {{{ForeignKey}}}, which is
why Zanuda999 couldn't replicate it. So, given these models:
{{{
class Model1(models.Model):
field1 = models.CharField(max_length=20)
class Model2(models.Model):
field1 = models.CharField(max_length=20, blank=True, null=True)
field2 = models.CharField(max_length=20, blank=True, null=True)
model1 = models.ForeignKey(Model1)
}}}
Create and run the migrations, then in the shell:
{{{
>>> m=Model1.objects.create(field1='foo')
>>> Model2.objects.create(model1=m)
}}}
Now, delete the {{{null=True}}} from Model2.field1 and field2, and create
migrations again, using a one-off default of {{{''}}} for both fields.
Running migrations now produces this error:
{{{
Running migrations:
Rendering model states... DONE
Applying null_to_blank.0002_auto_20150711_1244...Traceback (most recent
call last):
File "./manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File
"/Users/danielroseman/Projects/django/django/core/management/__init__.py",
line 331, in execute_from_command_line
utility.execute()
File
"/Users/danielroseman/Projects/django/django/core/management/__init__.py",
line 323, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File
"/Users/danielroseman/Projects/django/django/core/management/base.py",
line 350, in run_from_argv
self.execute(*args, **cmd_options)
File
"/Users/danielroseman/Projects/django/django/core/management/base.py",
line 401, in execute
output = self.handle(*args, **options)
File
"/Users/danielroseman/Projects/django/django/core/management/commands/migrate.py",
line 195, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File
"/Users/danielroseman/Projects/django/django/db/migrations/executor.py",
line 110, in migrate
self.apply_migration(states[migration], migration, fake=fake,
fake_initial=fake_initial)
File
"/Users/danielroseman/Projects/django/django/db/migrations/executor.py",
line 148, in apply_migration
state = migration.apply(state, schema_editor)
File
"/Users/danielroseman/Projects/django/django/db/migrations/migration.py",
line 116, in apply
operation.database_forwards(self.app_label, schema_editor, old_state,
project_state)
File
"/Users/danielroseman/Projects/django/django/db/migrations/operations/fields.py",
line 201, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File
"/Users/danielroseman/Projects/django/django/db/backends/base/schema.py",
line 482, in alter_field
old_db_params, new_db_params, strict)
File
"/Users/danielroseman/Projects/django/django/db/backends/base/schema.py",
line 654, in _alter_field
params,
File
"/Users/danielroseman/Projects/django/django/db/backends/base/schema.py",
line 110, in execute
cursor.execute(sql, params)
File "/Users/danielroseman/Projects/django/django/db/backends/utils.py",
line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/Users/danielroseman/Projects/django/django/db/backends/utils.py",
line 64, in execute
return self.cursor.execute(sql, params)
File "/Users/danielroseman/Projects/django/django/db/utils.py", line 95,
in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/Users/danielroseman/Projects/django/django/db/backends/utils.py",
line 64, in execute
return self.cursor.execute(sql, params)
django.db.utils.OperationalError: cannot ALTER TABLE
"null_to_blank_model2" because it has pending trigger events
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/25105#comment:3>
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