错误
我正在使用django和Spirit构建一个网站。在测试过程中，当我向名为spirit_category_category的表中插入新数据时，出现了以下错误：
django.db.utils.IntegrityError: duplicate key value violates unique constraint "spirit_category_category_pkey"
DETAIL: Key (id)=(1) already exists.
请注意，表中已经有其他两条记录，其id分别为
1和2。因此，插入Key(id)=(1)肯定行不通。但执行的sql语句并没有包括id字段。也就是说，Key (id)=(1)是由PostgreSQL自动生成的，那么它为什么会生成一个已经存在的id呢？
原因
为了找出原因，我在PostgreSQL中运行了以下命令：test_spiritdb=# select start_value, last_value, max_value from spirit_category_category_id_seq;
start_value | last_value | max_value
-------------+------------+---------------------
1 | 1 | 9223372036854775807
(1 row)
基本上，last_value 是 1，所以postgresql每次都会生成Key (id)=(1)。我尝试将其更改为3，一切正常。
test_spiritdb=# alter sequence spirit_category_category_id_seq restart with 3;
我不知道如何为测试修复它
测试通过了。但是这只是一个测试，所以修改测试表是没有意义的，因为测试数据库将在每次测试时被删除并重新创建，所以下一次测试仍将失败，因为last_value仍将生成为1。那么我想知道为什么django/postgresql会为last_value生成这样一个异常值？如何修复它？如果有帮助，以下是category的模型和迁移。
models.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.core.urlresolvers import reverse
from django.conf import settings
from .managers import CategoryQuerySet
from ..core.utils.models import AutoSlugField
class Category(models.Model):
parent = models.ForeignKey('self', verbose_name=_("category parent"), null=True, blank=True)
title = models.CharField(_("title"), max_length=75)
slug = AutoSlugField(populate_from="title", db_index=False, blank=True)
description = models.CharField(_("description"), max_length=255, blank=True)
is_global = models.BooleanField(_("global"), default=True,
help_text=_('Designates whether the topics will be'
'displayed in the all-categories list.'))
is_closed = models.BooleanField(_("closed"), default=False)
is_removed = models.BooleanField(_("removed"), default=False)
is_private = models.BooleanField(_("private"), default=False)
# topic_count = models.PositiveIntegerField(_("topic count"), default=0)
objects = CategoryQuerySet.as_manager()
class Meta:
ordering = ['title', 'pk']
verbose_name = _("category")
verbose_name_plural = _("categories")
def get_absolute_url(self):
if self.pk == settings.ST_TOPIC_PRIVATE_CATEGORY_PK:
return reverse('spirit:topic:private:index')
else:
return reverse('spirit:category:detail', kwargs={'pk': str(self.id), 'slug': self.slug})
@property
def is_subcategory(self):
if self.parent_id:
return True
else:
return False
0001_initial.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models, migrations
import spirit.core.utils.models
class Migration(migrations.Migration):
dependencies = [
]
operations = [
migrations.CreateModel(
name='Category',
fields=[
('id', models.AutoField(primary_key=True, verbose_name='ID', serialize=True, auto_created=True)),
('title', models.CharField(verbose_name='title', max_length=75)),
('slug', spirit.core.utils.models.AutoSlugField(db_index=False, populate_from='title', blank=True)),
('description', models.CharField(verbose_name='description', max_length=255, blank=True)),
('is_closed', models.BooleanField(verbose_name='closed', default=False)),
('is_removed', models.BooleanField(verbose_name='removed', default=False)),
('is_private', models.BooleanField(verbose_name='private', default=False)),
('parent', models.ForeignKey(null=True, verbose_name='category parent', to='spirit_category.Category', blank=True)),
],
options={
'ordering': ['title', 'pk'],
'verbose_name': 'category',
'verbose_name_plural': 'categories',
},
),
]
0002_auto_20150728_0442.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models, migrations
from django.conf import settings
def default_categories(apps, schema_editor):
Category = apps.get_model("spirit_category", "Category")
if not Category.objects.filter(pk=settings.ST_TOPIC_PRIVATE_CATEGORY_PK).exists():
Category.objects.create(
pk=settings.ST_TOPIC_PRIVATE_CATEGORY_PK,
title="Private",
slug="private",
is_private=True
)
if not Category.objects.filter(pk=settings.ST_UNCATEGORIZED_CATEGORY_PK).exists():
Category.objects.create(
pk=settings.ST_UNCATEGORIZED_CATEGORY_PK,
title="Uncategorized",
slug="uncategorized"
)
class Migration(migrations.Migration):
dependencies = [
('spirit_category', '0001_initial'),
]
operations = [
migrations.RunPython(default_categories),
]
0003_category_is_global.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models, migrations
class Migration(migrations.Migration):
dependencies = [
('spirit_category', '0002_auto_20150728_0442'),
]
operations = [
migrations.AddField(
model_name='category',
name='is_global',
field=models.BooleanField(default=True, help_text='Designates whether the topics will bedisplayed in the all-categories list.', verbose_name='global'),
),
]
id插入了表中，就像你所说的那样。我删除了id部分，一切又恢复正常了。谢谢！ - Searene