model Meta verbose_name too long error message not obvious

[Elena Williams]

Running:

$ python manage.py syncdb

The following error messages:

Postgres:

Creating tables ...
Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Library/Python/2.7/site-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
    utility.execute()
  File "/Library/Python/2.7/site-packages/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Library/Python/2.7/site-packages/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Library/Python/2.7/site-packages/django/core/management/base.py", line 232, in execute
    output = self.handle(*args, **options)
  File "/Library/Python/2.7/site-packages/django/core/management/base.py", line 371, in handle
    return self.handle_noargs(**options)
  File "/Library/Python/2.7/site-packages/django/core/management/commands/syncdb.py", line 110, in handle_noargs
    emit_post_sync_signal(created_models, verbosity, interactive, db)
  File "/Library/Python/2.7/site-packages/django/core/management/sql.py", line 189, in emit_post_sync_signal
    interactive=interactive, db=db)
  File "/Library/Python/2.7/site-packages/django/dispatch/dispatcher.py", line 172, in send
    response = receiver(signal=self, sender=sender, **named)
  File "/Library/Python/2.7/site-packages/django/contrib/auth/management/__init__.py", line 54, in create_permissions
    auth_app.Permission.objects.bulk_create(objs)
  File "/Library/Python/2.7/site-packages/django/db/models/manager.py", line 140, in bulk_create
    return self.get_query_set().bulk_create(*args, **kwargs)
  File "/Library/Python/2.7/site-packages/django/db/models/query.py", line 416, in bulk_create
    self.model._base_manager._insert(objs_without_pk, fields=[f for f in fields if not isinstance(f, AutoField)], using=self.db)
  File "/Library/Python/2.7/site-packages/django/db/models/manager.py", line 203, in _insert
    return insert_query(self.model, objs, fields, **kwargs)
  File "/Library/Python/2.7/site-packages/django/db/models/query.py", line 1576, in insert_query
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/Library/Python/2.7/site-packages/django/db/models/sql/compiler.py", line 910, in execute_sql
    cursor.execute(sql, params)
  File "/Library/Python/2.7/site-packages/django/db/backends/util.py", line 40, in execute
    return self.cursor.execute(sql, params)
  File "/Library/Python/2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 52, in execute
    return self.cursor.execute(query, args)
django.db.utils.DatabaseError: value too long for type character varying(50)

MySQL:

Creating tables ...
Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
    utility.execute()
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/core/management/base.py", line 232, in execute
    output = self.handle(*args, **options)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/core/management/base.py", line 371, in handle
    return self.handle_noargs(**options)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/core/management/commands/syncdb.py", line 110, in handle_noargs
    emit_post_sync_signal(created_models, verbosity, interactive, db)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/core/management/sql.py", line 189, in emit_post_sync_signal
    interactive=interactive, db=db)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/dispatch/dispatcher.py", line 172, in send
    response = receiver(signal=self, sender=sender, **named)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/contrib/auth/management/__init__.py", line 54, in create_permissions
    auth_app.Permission.objects.bulk_create(objs)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/db/models/manager.py", line 140, in bulk_create
    return self.get_query_set().bulk_create(*args, **kwargs)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/db/models/query.py", line 416, in bulk_create
    self.model._base_manager._insert(objs_without_pk, fields=[f for f in fields if not isinstance(f, AutoField)], using=self.db)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/db/models/manager.py", line 203, in _insert
    return insert_query(self.model, objs, fields, **kwargs)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/db/models/query.py", line 1576, in insert_query
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 910, in execute_sql
    cursor.execute(sql, params)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/db/backends/util.py", line 40, in execute
    return self.cursor.execute(sql, params)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 114, in execute
    return self.cursor.execute(query, args)
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/MySQLdb/cursors.py", line 176, in execute
    if not self._defer_warnings: self._warning_check()
  File "/Users/elena/.virtualenvs/wc/lib/python2.7/site-packages/MySQLdb/cursors.py", line 92, in _warning_check
    warn(w[-1], self.Warning, 3)
_mysql_exceptions.Warning: Data truncated for column 'name' at row 13

What is this error?

It is caused by contenttypes.name, see SO:
​http://stackoverflow.com/questions/10855978/heroku-and-django-value-too-long-for-type-character-varying50

Easily replicated:

class MyModel(models.Model):
    class Meta:
        verbose_name = "soem ridiculously long verbose name that is out of control"

This is not serious. It's just not obvious.

[Aymeric Augustin]

Yes, I've hit that several times myself. It's annoying. syncdb crashes because it tries to create a permission with a name that's longer than 50 characters.

Possible solutions:

• improve the error message
• display a warning and truncate the value
• increase the size of the field to 200 characters (insert usual rant about lack of migrations in core here)

[djangsters]

I added a simple validation before bulk_creation and a hint to the verbose_name
see: ​https://github.com/django/django/pull/1140

[Filipa Andrade]

Wouldn't it be good to have a test for this?

[kerry@…]

This also applies with a very similar error if you create your own Model permissions in Meta with a description over 50 Chars,

class Meta:
        permissions = (
            ("view_desks", "Can view desks"),
            ("track_attendance", "Can track attended/no-show with this unfeasibly long description of over 50 Chars"),
        )

I've added this comment in case it's useful to someone else following the same route as me when identifying the problem.

Would it make sense to fix under this ticket or shall I put in a new ticket?

[rasca]

Related to #18959 that tracks the table names errors

[toyg]

Ok, the problem is a bit more complex, and the abovementioned patch does not fix it.

The problem is that verbose_name is used to generate the auth_permission table; the "name" field in that table is set to varchar(50) (at least on PostgreSQL), but this record actually includes sentences ("Can add <verbose_name>", "Can delete <verbose_name>" and so on); so the actual practical limit is 39 characters for verbose_name. This is a weird number, common knowledge is that verbose_name can be up to 50 characters.

So the real fix is either to widen that field to 61 or more (50 + "Can delete ", which is 11 characters), or document that the limit is 39 on non-sqlite backends (sqlite doesn't really enforce limits to text fields).

I have a test and a fix for the validator to spot values that are too long, but there's no point in submitting a pull request if this point isn't settled first.

[toyg]

Duplicate of #8548 and #8162

[toyg]

Ok, using this bug to track *validation* only - the actual limit will stay at 39 as per #8162.

[joaoxsouls <joaoxsouls@…>]

In 1ab27e9a65015373a49688f3ff6723cf85d5de56:

Fixed #18866 -- added validation error for verbose_name longer than 39 characters

Added a validation error check when creating the permissions for model, to avoid
cryptic database error when the verbose_name is longer than 39 characters
thanks elena for reporting it

[Marc Tamlyn <marc.tamlyn@…>]

In 8ce3c3a9282ac19282060ddf6928b34a09d26672:

Merge pull request #1733 from joaoxsouls/#18866

Fixed #18866 -- added validation error for verbose_name longer than 39 characters

[Tim Graham <timograham@…>]

In 91c77eeab837ff793311ac5b0321015a4e66d6da:

Avoided hardcoding Permission.name max_length

refs #18866.