完整性错误 - get_or_create表示导入数据时不能为NULL

时间：2013-10-22 16:24:41

标签： python-2.7 csv model django-south django-1.5

我问a question to try and fix an issue我在哪里，我不明白如何正确使用ForeignKeys。这是非常有用的修复，虽然我有django.db.utils.IntegrityError: core_team.blahblah_id may not be NULL的后续问题，我决定回滚，做一些稍微简单的事情 - 为了避免双重查找（匹配与团队和联盟相关），我会写一个管理命令来导入团队。

根据上一个问题我的（明显有缺陷的）理解，我做得对 - 它使用get_or_create来检查联盟实例，然后根据该分配给团队。我还仔细检查了数据库是最新的（我正在向南运行，并且在我最后一次更改方案时进行了向前迁移，从那以后没有任何改变。最后的改变是使两个模型中的名称成为主键（因为每个名字只有一个团队，每个名字只有一个联盟。）

最近，我添加了代码以向团队get_or_create部分提供默认值，但是我收到了相同的错误。我理解错误的原因（我认为） - 团队中的ForeignKey'盟'已存在于数据库中，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） ，只是没有如何解决它。

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

models.py的相关部分：

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 - 我认为这里说联盟_id很奇怪，因为这不应该再相关了吗？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

这是什么使这个问题永久化？

编辑：似乎没有。删除了数据库并移动了南迁移文件夹，它仍然在执行它。源CSV也很好（没有空白行或空字符串/段），上面的代码有一个部分可以跳过这些段;它没有那么远。

1 个答案:

答案 0 :(得分：1)

唉。对于其他任何后来出现的新手来说，这个答案实际上很荒谬。我在这里做的是在'Team'表中创建一个条目，其中有一个ForeignKey回到'League'。

'技巧'（这不是一个技巧，只是在文档中非常糟糕地解释，imho）是你在为Team对象执行get_or_create时需要明确地传递联盟。 不只是匹配团队名称

我以为我已经做到了，但我没有，它出现了。此代码有效（并且非常有效地确保没有重复）：

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], league=league)
        current_team = Team(league = league, team_name=team)
    print current_team
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