加载 Django 夹具时出现问题：IntegrityError: (1062, "Duplicate entry '4' for key 'user_id'")答案

【问题标题】：Problem loading Django fixture: IntegrityError: (1062, "Duplicate entry '4' for key 'user_id'")加载 Django 夹具时出现问题：IntegrityError: (1062, "Duplicate entry '4' for key 'user_id'")
【发布时间】：2011-04-18 01:52:22
【问题描述】：

我使用以下命令生成了 2 个灯具：

./manage.py dumpdata --format=json --indent=4 --natural auth.User > fixtures/user.json
./manage.py dumpdata --format=json --indent=4 --natural --exclude=contenttypes --exclude=auth > fixtures/full.json

我有以下名为 user.json 的夹具：

[
    {
        "pk": 4, 
        "model": "auth.user", 
        "fields": {
            "username": "foo", 
            "first_name": "Se\u00e1n", 
            "last_name": "Hayes", 
            "is_active": true, 
            "is_superuser": true, 
            "is_staff": true, 
            "last_login": "2010-09-27 21:57:45", 
            "groups": [], 
            "user_permissions": [], 
            "password": "!", 
            "email": "foo@gmail.com", 
            "date_joined": "2010-09-27 21:57:45"
        }
    }
]

以及名为 full.json 的以下夹具：

[
    {
        "pk": "72a75887b4a0ce06a61f9183fe1c0e15", 
        "model": "sessions.session", 
        "fields": {
            "expire_date": "2010-10-11 21:57:45", 
            "session_data": "gAJ9cQEoVRJfYXV0aF91c2VyX2JhY2tlbmRxAlUOZmIuYXV0aC5GYkF1dGhxA1UNX2F1dGhfdXNl\ncl9pZHEEigEEdS5hOGZlODU0MmRjYmUwNmEzODIwNjhiYzYyODc2MWQxZA==\n"
        }
    }, 
    {
        "pk": 1, 
        "model": "sites.site", 
        "fields": {
            "domain": "example.com", 
            "name": "example.com"
        }
    }, 
    {
        "pk": 2, 
        "model": "common.userprofile", 
        "fields": {
            "money": 10, 
            "energy": 10, 
            "experience": 0, 
            "stamina": 10, 
            "health": 10, 
            "user": 4
        }
    }, 
    {
        "pk": 2, 
        "model": "missions.missionprofile", 
        "fields": {
            "user": 4, 
            "last_area_viewed": null
        }
    }, 
    {
        "pk": 1, 
        "model": "fb.facebookuser", 
        "fields": {
            "updated": "2010-09-27 21:57:45", 
            "uid": "24411841", 
            "created": "2010-09-27 21:57:45", 
            "access_token": "foo", 
            "url": "http://www.facebook.com/profile.php?id=24411841", 
            "user": 4, 
            "img_url": null, 
            "name": "Se\u00e1n Hayes"
        }
    }
]

运行以下命令（按任意顺序）：

./manage.py loaddata user
./manage.py loaddata full

引发以下异常：

Problem installing fixture '/projectpath/fixtures/full.json': Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.6/django/core/management/commands/loaddata.py", line 169, in handle
    obj.save(using=using)
  File "/usr/lib/pymodules/python2.6/django/core/serializers/base.py", line 165, in save
    models.Model.save_base(self.object, using=using, raw=True)
  File "/usr/lib/pymodules/python2.6/django/db/models/base.py", line 528, in save_base
    result = manager._insert(values, return_id=update_pk, using=using)
  File "/usr/lib/pymodules/python2.6/django/db/models/manager.py", line 195, in _insert
    return insert_query(self.model, values, **kwargs)
  File "/usr/lib/pymodules/python2.6/django/db/models/query.py", line 1479, in insert_query
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/usr/lib/pymodules/python2.6/django/db/models/sql/compiler.py", line 783, in execute_sql
    cursor = super(SQLInsertCompiler, self).execute_sql(None)
  File "/usr/lib/pymodules/python2.6/django/db/models/sql/compiler.py", line 727, in execute_sql
    cursor.execute(sql, params)
  File "/usr/lib/pymodules/python2.6/django/db/backends/util.py", line 15, in execute
    return self.cursor.execute(sql, params)
  File "/usr/lib/pymodules/python2.6/django/db/backends/mysql/base.py", line 86, in execute
    return self.cursor.execute(query, args)
  File "/usr/lib/pymodules/python2.6/MySQLdb/cursors.py", line 166, in execute
    self.errorhandler(self, exc, value)
  File "/usr/lib/pymodules/python2.6/MySQLdb/connections.py", line 35, in defaulterrorhandler
    raise errorclass, errorvalue
IntegrityError: (1062, "Duplicate entry '4' for key 'user_id'")

对正在发生的事情有任何想法吗？我知道 MySQL 中的前向引用存在问题，但如果 ID 为 4 的 User 对象安装在包含外键的固定装置之前，这无关紧要，对吧？

【问题讨论】：

我还尝试将 full.json 拆分为较小的装置，并一次安装一个。一旦存在 User 的外键，就会生成错误。
你能把你的模型的代码贴在这里吗？
你的模型有unique设置吗？
您是否有任何信号可以在创建用户后立即在common.userprofile 中创建条目？
Ashok，是的，就是这样。我不认为有任何办法让夹具覆盖信号生成的模型。

标签： python mysql django fixtures mysql-error-1062

【解决方案1】：

Django 的静态夹具是一种 ANTI-PATTERN，这就是您遇到此类问题的原因。我建议您使用一些为您生成此固定装置的库，自然包括 ID。

我建议你Dynamic Dynamic Fixture

【讨论】：

【解决方案2】：

根据 Ashok 的评论，当我遇到同样的问题时，通过更改我的信号处理程序来检查它是否在“原始”模式下运行，这显然意味着正在加载一个夹具：

def create_user_profile(sender, instance, created, **kwargs):
    if created and not kwargs.get('raw', False): 
        UserProfile.objects.create(user=instance)

见How do I prevent fixtures from conflicting with django post_save signal code?

【讨论】：