Django：迁移错误中的loaddata

3 回答

• 2

  当您运行 python manage.py migrate 时，它正在尝试在 fixtures 文件夹中加载 testmodel.json ，但您的模型（更新后）与 testmodel.json 中的数据不匹配 . 你可以试试这个：

  • 将目录从 fixture 更改为 _fixture .

  • 运行 python manage.py migrate

  • 可选，您现在可以通过 fixture 更改 _fixture 并使用 migrate 命令加载数据或使用 python manage.py loaddata app/_fixtures/testmodel.json 加载数据

  回复于 2024-04-25T04:31:40+08:00
• 7

  扩展GwynBleidD的答案并混合使用此问题，因为Postgres在以这种方式加载时不会重置主键序列（https://stackoverflow.com/a/14589706/401636）

  我想我现在有一个加载夹具数据的故障安全迁移 .

  utils.py：

  import os
  
  from io import StringIO
  
  import django.apps
  
  from django.conf import settings
  from django.core import serializers
  from django.core.management import call_command
  from django.db import connection
  
  
  os.environ['DJANGO_COLORS'] = 'nocolor'
  
  
  def reset_sqlsequence(apps=None, schema_editor=None):
      """Suitable for use in migrations.RunPython"""
  
      commands = StringIO()
      cursor = connection.cursor()
      patched = False
  
      if apps:
          # Monkey patch django.apps
          original_apps = django.apps.apps
          django.apps.apps = apps
          patched = True
      else:
          # If not in a migration, use the normal apps registry
          apps = django.apps.apps
  
      for app in apps.get_app_configs():
          # Generate the sequence reset queries
          label = app.label
          if patched and app.models_module is None:
              # Defeat strange test in the mangement command
              app.models_module = True
          call_command('sqlsequencereset', label, stdout=commands)
          if patched and app.models_module is True:
              app.models_module = None
  
      if patched:
          # Cleanup monkey patch
          django.apps.apps = original_apps
  
      sql = commands.getvalue()
      print(sql)
      if sql:
          # avoid DB error if sql is empty
          cursor.execute(commands.getvalue())
  
  
  class LoadFixtureData(object):
      def __init__(self, *files):
          self.files = files
  
      def __call__(self, apps=None, schema_editor=None):
          if apps:
              # If in a migration Monkey patch the app registry
              original_apps = serializers.python.apps
              serializers.python.apps = apps
  
          for fixture_file in self.files:
              with open(fixture_file) as fixture:
                  objects = serializers.deserialize('json', fixture)
  
                  for obj in objects:
                      obj.save()
  
          if apps:
              # Cleanup monkey patch
              serializers.python.apps = original_apps
  

  现在我的数据迁移看起来像：

  # -*- coding: utf-8 -*-
  # Generated by Django 1.11.1 on foo
  from __future__ import unicode_literals
  
  import os
  
  from django.conf import settings
  from django.db import migrations
  
  from .utils import LoadFixtureData, reset_sqlsequence
  
  
  class Migration(migrations.Migration):
  
      dependencies = [
          ('app_name', '0002_auto_foo'),
      ]
  
      operations = [
          migrations.RunPython(
              code=LoadFixtureData(*[
                  os.path.join(settings.BASE_DIR, 'app_name', 'fixtures', fixture) + ".json"
                  for fixture in ('fixture_one', 'fixture_two',)
              ]),
              # Reverse will NOT remove the fixture data
              reverse_code=migrations.RunPython.noop,
          ),
          migrations.RunPython(
              code=reset_sqlsequence,
              reverse_code=migrations.RunPython.noop,
          ),
      ]
  

  回复于 2024-04-25T04:31:40+08:00
• 2

  loaddata 命令只会调用序列化程序 . 序列化程序将处理来自 models.py 文件的模型状态，而不是当前迁移，但是没有什么技巧可以欺骗默认的序列化程序 .

  首先，您不希望 call_command 使用该序列化程序，而是直接使用该序列化程序：

  from django.core import serializers
  
  def load_fixture(apps, schema_editor):
      fixture_file = '/full/path/to/testmodel.json'
      fixture = open(fixture_file)
      objects = serializers.deserialize('json', fixture, ignorenonexistent=True)
      for obj in objects:
          obj.save()
      fixture.close()
  

  其次，序列化器使用的monkey-patch apps注册表：

  from django.core import serializers
  
  def load_fixture(apps, schema_editor):
      original_apps = serializers.python.apps
      serializers.python.apps = apps
      fixture_file = '/full/path/to/testmodel.json'
      fixture = open(fixture_file)
      objects = serializers.deserialize('json', fixture, ignorenonexistent=True)
      for obj in objects:
          obj.save()
      fixture.close()
      serializers.python.apps = original_apps
  

  现在，序列化程序将使用 apps 中的模型状态而不是默认状态，整个迁移过程将成功 .

  回复于 2024-04-25T04:31:40+08:00