我问了一个问题，试图解决一个我不明白如何正确使用 ForeignKeys 的问题。这是非常有帮助的修复，虽然我有一个随后的问题， django.db.utils.IntegrityError: core_team.blahblah_id may not be NULL我决定回滚，做一些稍微简单的事情 - 为了避免双重查找（比赛链接到球队和联赛），我会写一个管理命令导入团队。
根据我对上一个问题的（明显有缺陷的）理解，我做得对 - 它用于get_or_create检查联赛实例，然后根据它分配球队。我还仔细检查了数据库是否是最新的（我正在向南运行并在我上次更改方案时进行了前向迁移，从那时起没有任何变化。最后一次更改是使两个模型中的名称成为主键（因为每个名字只有一支球队，每个名字只有一个联赛。）
最近，我添加了代码来为团队 get_or_create 部分提供默认值，但我收到了同样的错误。我理解错误的原因（我认为） - Team 中的 ForeignKey 'league' 已经存在于数据库中，并且不能为空插入另一个团队（来自https://docs.djangoproject.com/en/1.5 /ref/models/querysets/#get-or-create），只是不知道如何修复它。
管理命令：
from django.core.management.base import BaseCommand, CommandError
import csv
import csvImporter
#from core.models import Match
from time import strptime
from datetime import datetime
master_data = open ('/Users/chris/Desktop/AllDataTruncated.csv', 'r')
data = list(tuple(rec) for rec in csv.reader(master_data, delimiter=','))
from core.models import League, Team
team_list = []
for row in data:
if row[2] == "HomeTeam":
print "Continuing"
continue
elif row[2] == "":
print "Continuing"
continue
else:
league, _ = League.objects.get_or_create(name=row[0])
print league
team, _ = Team.objects.get_or_create(team_name=row[2], defaults={'league':league})
current_team = Team(league = league, team_name=team)
print current_team
和models.py的相关位：
class League (models.Model):
name = models.CharField(max_length=2, primary_key=True)
last_modified = models.CharField(max_length=50)
def __unicode__(self):
return unicode(self.name)
class Team(models.Model):
team_name = models.CharField(max_length=50, primary_key=True)
league = models.ForeignKey(League)
team_colour = models.CharField(max_length=6, null=True, blank=True)
def __unicode__(self):
return unicode (self.team_name)
完整的追溯是：
$ python manage.py importteams
Continuing
E0
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 453, in execute_from_command_line
utility.execute()
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 272, in fetch_command
klass = load_command_class(app_name, subcommand)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/management/__init__.py", line 77, in load_command_class
module = import_module('%s.management.commands.%s' % (app_name, name))
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/utils/importlib.py", line 35, in import_module
__import__(name)
File "/Users/chris/Dropbox/Django/gmblnew/core/management/commands/importteams.py", line 26, in <module>
team2, _ = Team.objects.get_or_create(team_name=row[3])
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/manager.py", line 146, in get_or_create
return self.get_query_set().get_or_create(**kwargs)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/query.py", line 487, in get_or_create
six.reraise(*exc_info)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/query.py", line 477, in get_or_create
obj.save(force_insert=True, using=self.db)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/base.py", line 546, in save
force_update=force_update, update_fields=update_fields)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/base.py", line 650, in save_base
result = manager._insert([self], fields=fields, return_id=update_pk, using=using, raw=raw)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/manager.py", line 215, in _insert
return insert_query(self.model, objs, fields, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/query.py", line 1661, in insert_query
return query.get_compiler(using=using).execute_sql(return_id)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 937, in execute_sql
cursor.execute(sql, params)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/util.py", line 41, in execute
return self.cursor.execute(sql, params)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/sqlite3/base.py", line 364, in execute
six.reraise(utils.IntegrityError, utils.IntegrityError(*tuple(e.args)), sys.exc_info()[2])
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/backends/sqlite3/base.py", line 362, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: core_team.league_id may not be NULL
现在 - 我认为它在这里说 League_id 很奇怪，因为这应该不再相关了？当我进行迁移时，问题出现了：
? The field 'League.id' does not have a default specified, yet is NOT NULL.
? Since you are removing this field, you MUST specify a default
? value to use for existing rows. Would you like to:
? 1. Quit now.
? 2. Specify a one-off value to use for existing columns now
? 3. Disable the backwards migration by raising an exception; you can edit the migration to fix it later
? Please select a choice: 3
这是使这个问题长期存在的原因吗？
编辑：似乎没有。删除了 DB 并移动了 South migrations 文件夹，它仍在执行此操作。源 CSV 也很好（没有空行或空字符串/段），上面的代码有一个部分可以跳过这些段；它没有那么远。