django - 无法迁移，django.db.migrations.exceptions.MigrationSchemaMissing

Question

我的数据库中没有有值(value)的数据，无法迁移，如您在此处所见:

ResetDjango postgresql database? flush does not work

我尝试使用以下方法重置数据库:

1. Delete migration files
2. Enter psql command prompt. Connect to database. drop schema public cascade; create schema public;
3. Step 2 unfortunately seemed to have removed my user role and rights so I went back to the psql command promt and recreated those.

现在又试了一次迁移，还是不行。现在可能出了什么问题？

vagrant@vagrant-ubuntu-trusty-64:/vagrant/grader$ python3 manage.py makemigrations
Migrations for 'core':
  0001_initial.py:
    - Create model Student
vagrant@vagrant-ubuntu-trusty-64:/vagrant/grader$ python3 manage.py migrate     Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py", line 62, in execute
    return self.cursor.execute(sql)
psycopg2.ProgrammingError: no schema has been selected to create in


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/django/db/migrations/recorder.py", line 57, in ensure_schema
    editor.create_model(self.Migration)
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/base/schema.py", line 284, in create_model
    self.execute(sql, params or None)
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/base/schema.py", line 110, in execute
    cursor.execute(sql, params)
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/usr/local/lib/python3.4/dist-packages/django/db/utils.py", line 95, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/usr/local/lib/python3.4/dist-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py", line 62, in execute
    return self.cursor.execute(sql)
django.db.utils.ProgrammingError: no schema has been selected to create in


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.4/dist-packages/django/core/management/__init__.py", line 350, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.4/dist-packages/django/core/management/__init__.py", line 342, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python3.4/dist-packages/django/core/management/base.py", line 348, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python3.4/dist-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python3.4/dist-packages/django/core/management/commands/migrate.py", line 89, in handle
    executor = MigrationExecutor(connection, self.migration_progress_callback)
  File "/usr/local/lib/python3.4/dist-packages/django/db/migrations/executor.py", line 20, in __init__
    self.loader = MigrationLoader(self.connection)
  File "/usr/local/lib/python3.4/dist-packages/django/db/migrations/loader.py", line 49, in __init__
    self.build_graph()
  File "/usr/local/lib/python3.4/dist-packages/django/db/migrations/loader.py", line 176, in build_graph
    self.applied_migrations = recorder.applied_migrations()
  File "/usr/local/lib/python3.4/dist-packages/django/db/migrations/recorder.py", line 65, in applied_migrations
    self.ensure_schema()
  File "/usr/local/lib/python3.4/dist-packages/django/db/migrations/recorder.py", line 59, in ensure_schema
    raise MigrationSchemaMissing("Unable to create the django_migrations table (%s)" % exc)
django.db.migrations.exceptions.MigrationSchemaMissing: Unable to create the django_migrations table (no schema has been selected to create in
)

Answer 1

在顶部的settings.py中添加这两行对于mysql连接很重要:

from django.db.backends.mysql.base import DatabaseWrapper
DatabaseWrapper.data_types['DateTimeField']='datetime'