Problems with migrations cleaning up a date field

[Lee Hinde]

I'm having problems with a migration after cleaning up an oddity with a date field and I'm not sure how to fix it.  Any advice appreciated.

I made this change to a date field:

-    start_date = models.DateField(db_index=True, default=False,
-                                  help_text="The date enrollment can begin this Season.")
+    start_date = models.DateField(db_index=True, help_text="The date enrollment can begin this Season.")

I'm not sure how a default of False ever made it, but I ran across it and fixed it.

This is the migration that was created:

class Migration(migrations.Migration):

    dependencies = [
        ('district', '0012_auto_20160622_1741'),
    ]

    operations = [
        migrations.AlterField(
            model_name='season',
            name='start_date',
            field=models.DateField(help_text=b'The date enrollment can begin this Season.', db_index=True),
        ),
    ]

This is the error I get trying to run the migration:

  Applying district.0013_auto_20170204_1811...Traceback (most recent call last):

  File "manage.py", line 9, in <module>

    execute_from_command_line(sys.argv)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/core/management/__init__.py", line 354, in execute_from_command_line

    utility.execute()

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/core/management/__init__.py", line 346, in execute

    self.fetch_command(subcommand).run_from_argv(self.argv)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/core/management/base.py", line 394, in run_from_argv

    self.execute(*args, **cmd_options)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/core/management/base.py", line 445, in execute

    output = self.handle(*args, **options)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 222, in handle

    executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/migrations/executor.py", line 110, in migrate

    self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/migrations/executor.py", line 148, in apply_migration

    state = migration.apply(state, schema_editor)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/migrations/migration.py", line 115, in apply

    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/migrations/operations/fields.py", line 201, in database_forwards

    schema_editor.alter_field(from_model, from_field, to_field)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 484, in alter_field

    old_db_params, new_db_params, strict)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 566, in _alter_field

    old_default = self.effective_default(old_field)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 211, in effective_default

    default = field.get_db_prep_save(default, self.connection)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 710, in get_db_prep_save

    prepared=False)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1322, in get_db_prep_value

    value = self.get_prep_value(value)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1317, in get_prep_value

    return self.to_python(value)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1274, in to_python

    parsed = parse_date(value)

  File "/Users/leehinde/Documents/Clients/rnrvirtual/venv-python2.7-django/lib/python2.7/site-packages/django/utils/dateparse.py", line 60, in parse_date

    match = date_re.match(value)

TypeError: expected string or buffer

[Lee Hinde]

I should add, this project is in 1.8.x. I'm working around the problem by skipping the migration.

[James Schneider]

On Jun 9, 2017 6:09 PM, "Lee Hinde" <leeh...@gmail.com> wrote:

I'm having problems with a migration after cleaning up an oddity with a date field and I'm not sure how to fix it.  Any advice appreciated.

I made this change to a date field:

-    start_date = models.DateField(db_index=True, default=False,
-                                  help_text="The date enrollment can begin this Season.")
+    start_date = models.DateField(db_index=True, help_text="The date enrollment can begin this Season.")

I'm not sure how a default of False ever made it, but I ran across it and fixed it.

Have you verified that every row has a value for start_date? The error sounds like either your start_dates are missing/have null values, or you have a bad value somewhere.

Quite honestly this sounds like a bug in the migration system if that's the case. I'm pretty sure it should ask what value to use as a filler value during the migration, although I haven't had a change like that in a while.

-James

[Melvyn Sopacua]

On Friday 09 June 2017 20:56:46 James Schneider wrote:

 

> Quite honestly this sounds like a bug in the migration system if

> that's the case. I'm pretty sure it should ask what value to use as a

> filler value during the migration, although I haven't had a change

> like that in a while.

 

When you *remove* a default, there is no need to migrate existing rows, as they have a default.

--

Melvyn Sopacua

[Melvyn Sopacua]

On Friday 09 June 2017 18:08:39 Lee Hinde wrote:

> I'm having problems with a migration after cleaning up an oddity with

> a date field and I'm not sure how to fix it. Any advice appreciated.

>

> I made this change to a date field:

>

> - start_date = models.DateField(db_index=True, default=False,

> - help_text="The date enrollment can

> begin this Season.")

 

Apparently, this goes through, even though it's not a valid default for a date field (tested with 1.11.2). So that is the bug in the migrations system.

 

Is it possible for you to rollback to before this migration or has this hit production already?

--

Melvyn Sopacua

[Lee Hinde]

I should have mentioned that I checked for empty date fields first and they were all populated.

My work around was to skip the migration. Just redid the dependency on the next migration and all was well.

Thanks.