我对 django 非常陌生,并且能够在 djangoproject.com 上完成教程而没有任何错误。我现在正在阅读 http://www.django-rest-framework.org/ 上的 Django REST 框架教程。 我几乎完成了它,只是添加了身份验证。现在我得到了:
OperationalError at /snippets/
no such column: snippets_snippet.owner_id
Request Method: GET
Request URL: http://localhost:8000/snippets/
Django Version: 1.7
Exception Type: OperationalError
Exception Value:
no such column: snippets_snippet.owner_id
Exception Location: /Users/taylorallred/Desktop/env/lib/python2.7/site-packages/django/db/backends/sqlite3/base.py in execute, line 485
Python Executable: /Users/taylorallred/Desktop/env/bin/python
Python Version: 2.7.5
Python Path:
['/Users/taylorallred/Desktop/tutorial',
'/Users/taylorallred/Desktop/env/lib/python27.zip',
'/Users/taylorallred/Desktop/env/lib/python2.7',
'/Users/taylorallred/Desktop/env/lib/python2.7/plat-darwin',
'/Users/taylorallred/Desktop/env/lib/python2.7/plat-mac',
'/Users/taylorallred/Desktop/env/lib/python2.7/plat-mac/lib-scriptpackages',
'/Users/taylorallred/Desktop/env/Extras/lib/python',
'/Users/taylorallred/Desktop/env/lib/python2.7/lib-tk',
'/Users/taylorallred/Desktop/env/lib/python2.7/lib-old',
'/Users/taylorallred/Desktop/env/lib/python2.7/lib-dynload',
'/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
'/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
'/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
'/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
'/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
'/Users/taylorallred/Desktop/env/lib/python2.7/site-packages']
Server time: Sat, 11 Oct 2014 07:02:34 +0000
我在网上找了几个地方,不只是 StackOverflow 的解决方案,似乎一般问题出在我的数据库上,需要删除它然后重新制作,我已经做了好几次了,教程甚至让我删除数据库并重新制作它。
这是我的 models.py
:
from django.db import models
from pygments.lexers import get_all_lexers
from pygments.styles import get_all_styles
from pygments.lexers import get_lexer_by_name
from pygments.formatters.html import HtmlFormatter
from pygments import highlight
LEXERS = [item for item in get_all_lexers() if item[1]]
LANGUAGE_CHOICES = sorted([(item[1][0], item[0]) for item in LEXERS])
STYLE_CHOICES = sorted((item, item) for item in get_all_styles())
class Snippet(models.Model):
owner = models.ForeignKey('auth.User', related_name='snippets')
highlighted = models.TextField()
created = models.DateTimeField(auto_now_add=True)
title = models.CharField(max_length=100, blank=True, default='')
code = models.TextField()
linenos = models.BooleanField(default=False)
language = models.CharField(choices=LANGUAGE_CHOICES,
default='python',
max_length=100)
style = models.CharField(choices=STYLE_CHOICES,
default='friendly',
max_length=100)
class Meta:
ordering = ('created',)
def save(self, *args, **kwargs):
"""
Use the 'pygments' library to create a highlighted HTML
representation of the code snippet.
"""
lexer = get_lexer_by_name(self.language)
linenos = self.linenos and 'table' or False
options = self.title and {'title': self.title} or {}
formatter = HtmlFormatter(style=self.style, linenos=linenos,
full=true, **options)
self.highlighted = highlight(self.code, lexer, formatter)
super(Snippet, self).save(*args, **kwargs)
我的serializers.py
:
from django.forms import widgets
from rest_framework import serializers
from snippets.models import Snippet, LANGUAGE_CHOICES, STYLE_CHOICES
from django.contrib.auth.models import User
class SnippetSerializer(serializers.ModelSerializer):
owner = serializers.Field(source='owner.username')
class Meta:
model = Snippet
fields = ('id', 'title', 'code', 'linenos', 'language', 'style', 'owner')
class UserSerializer(serializers.ModelSerializer):
snippets = serializers.PrimaryKeyRelatedField(many=True)
class Meta:
model = User
fields = ('id', 'username', 'snippets')
我的views.py
:
from snippets.models import Snippet
from snippets.serializers import SnippetSerializer
from rest_framework import generics
from django.contrib.auth.models import User
from snippets.serializers import UserSerializer
from rest_framework import permissions
class SnippetList(generics.ListCreateAPIView):
"""
List all snippets, or create a new snippet.
"""
queryset = Snippet.objects.all()
serializer_class = SnippetSerializer
def pre_save(self, obj):
obj.owner = self.request.user
permission_classes = (permissions.IsAuthenticatedOrReadOnly,)
class SnippetDetail(generics.RetrieveUpdateDestroyAPIView):
"""
Retrieve, update or delete a nippet instance.
"""
queryset = Snippet.objects.all()
serializer_class = SnippetSerializer
def pre_save(self, obj):
obj.owner = self.request.user
permission_classes = (permissions.IsAuthenticatedOrReadOnly,)
class UserList(generics.ListAPIView):
queryset = User.objects.all()
serializer_class = UserSerializer
class UserDetail(generics.RetrieveAPIView):
queryset = User.objects.all()
serializer_class = UserSerializer
最后是我的 urls.py
from django.conf.urls import include
from django.conf.urls import patterns, url
from rest_framework.urlpatterns import format_suffix_patterns
from snippets import views
urlpatterns = patterns('',
url(r'^snippets/$', views.SnippetList.as_view()),
url(r'^snippets/(?P<pk>[0-9]+)/$', views.SnippetDetail.as_view()),
url(r'^users/$', views.UserList.as_view()),
url(r'^users/(?P<pk>[0-9]+)/$', views.UserDetail.as_view()),
)
urlpatterns = format_suffix_patterns(urlpatterns)
urlpatterns += patterns('',
url(r'^api-auth/', include('rest_framework.urls',
namespace='rest_framework')),
)
如果我发布了一堆不必要的信息,我深表歉意。在此先感谢各位。
编辑: 数据库架构:
CREATE TABLE "snippets_snippet" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT,
"created" datetime NOT NULL, "title" varchar(100) NOT NULL, "code" text NOT NULL,
"linenos" bool NOT NULL, "language" varchar(100) NOT NULL, "style" varchar(100) NOT NULL);
在做了一些挖掘之后,我发现在删除和重新创建数据库时(如教程所说)而不是使用 make migrations
命令,它不仅不会添加列,而且也不会告诉我在运行它告诉我的 make migrations
命令时出了点问题:
You are trying to add a non-nullable field 'highlighted' to snippet without a default;
we can't do that (the database needs something to populate existing rows).
Please select a fix:
1) Provide a one-off default now (will be set on all existing rows)
2) Quit, and let me add a default in models.py
如果我注释掉 models.py
中的 highlighted
部分,它将在上面发布相同的消息,但针对 owner
行。所以它希望 highlighted
和 owner
都有一个默认值,但我不确定该使用什么。以及教程对我也没有帮助。
最佳答案
在阅读本教程时,您一定遇到过关于迁移的部分,因为这是 Django 1.7 的主要变化之一
在 Django 1.7 之前,syncdb 命令从未进行任何有机会破坏数据库中当前数据的更改。这意味着,如果您为模型执行了 syncdb,然后向模型添加了一个新行(实际上是一个新列),syncdb 不会影响数据库中的该更改。
因此,要么您手动删除该表,然后再次运行 syncdb(从头开始重新创建它,丢失任何数据),或者您在数据库中手动输入正确的语句以仅添加该列。
然后出现了一个名为 south
的项目,它实现了迁移。这意味着有一种方法可以向前迁移(以及反向、撤消)对数据库的任何更改并保持数据的完整性。
在 Django 1.7 中,south
的功能直接集成到 Django 中。使用迁移时,过程有点不同。
- 对
models.py
进行更改(正常)。 - 创建迁移。这会生成代码以从模型的当前状态转到下一个状态。这是通过
makemigrations
命令完成的。这个命令足够聪明,可以检测到发生了什么变化,并会创建一个脚本来影响数据库的变化。 - 接下来,您使用
migrate
应用该迁移。此命令按顺序应用所有迁移。
因此,您的正常 syncdb
现在是一个两步过程,python manage.py makemigrations
然后是 python manage.py migrate
。
现在,谈谈您的具体问题:
class Snippet(models.Model):
owner = models.ForeignKey('auth.User', related_name='snippets')
highlighted = models.TextField()
created = models.DateTimeField(auto_now_add=True)
title = models.CharField(max_length=100, blank=True, default='')
code = models.TextField()
linenos = models.BooleanField(default=False)
language = models.CharField(choices=LANGUAGE_CHOICES,
default='python',
max_length=100)
style = models.CharField(choices=STYLE_CHOICES,
default='friendly',
max_length=100)
在此模型中,您有两个字段 highlighted
和 code
是必需的(它们不能为空)。
如果您从一开始就添加了这些字段,不会因为表没有现有行而出现问题吗?
但是,如果表已经创建并且您添加了一个不能为空的字段,您必须为任何现有行定义一个默认值 - 否则,数据库将不会接受您的更改,因为它们会违反数据完整性约束。
这就是命令提示您的内容。您可以告诉 Django 在迁移期间应用默认值,或者您可以在模型本身中给它一个“空白”默认值 highlighted = models.TextField(default='')
。
关于python - OperationalError,没有这样的列。 Django ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26312219/