Rest 框架教程完整性创建代码段时出错

我正在学习 Django Rest Framework 教程，但我被困在第 4 部分。

向视图添加权限后，它说要创建几个片段。我通过可浏览的 API 登录并尝试发布这样的片段：

{
"title": "snippet",
"code": "print 123"
}

当我这样做时，我得到：

完整性错误在/片段/

NOT NULL 约束失败：snippets_snippet.owner_id

有人知道这里发生了什么吗？

Traceback:
File "/home/grez/restenv/lib/python3.4/site-packages/django/core/handlers/base.py" in get_response
  111.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/grez/restenv/lib/python3.4/site-packages/django/views/decorators/csrf.py" in wrapped_view
  57.         return view_func(*args, **kwargs)
File "/home/grez/restenv/lib/python3.4/site-packages/django/views/generic/base.py" in view
  69.             return self.dispatch(request, *args, **kwargs)
File "/home/grez/restenv/lib/python3.4/site-packages/rest_framework/views.py" in dispatch
  403.             response = self.handle_exception(exc)
File "/home/grez/restenv/lib/python3.4/site-packages/rest_framework/views.py" in dispatch
  400.             response = handler(request, *args, **kwargs)
File "/home/grez/web/resttutorial/snippets/views.py" in post
  23.             serializer.save()
File "/home/grez/restenv/lib/python3.4/site-packages/rest_framework/serializers.py" in save
  599.             self.save_object(self.object, **kwargs)
File "/home/grez/restenv/lib/python3.4/site-packages/rest_framework/serializers.py" in save_object
  1041.         obj.save(**kwargs)
File "/home/grez/web/resttutorial/snippets/models.py" in save
  36.         super(Snippet, self).save(*args, **kwargs)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/models/base.py" in save
  591.                        force_update=force_update, update_fields=update_fields)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/models/base.py" in save_base
  619.             updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/models/base.py" in _save_table
  700.             result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/models/base.py" in _do_insert
  733.                                using=using, raw=raw)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/models/manager.py" in manager_method
  92.                 return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/models/query.py" in _insert
  921.         return query.get_compiler(using=using).execute_sql(return_id)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/models/sql/compiler.py" in execute_sql
  920.                 cursor.execute(sql, params)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
  81.             return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
  65.                 return self.cursor.execute(sql, params)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/utils.py" in __exit__
  94.                 six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/grez/restenv/lib/python3.4/site-packages/django/utils/six.py" in reraise
  549.             raise value.with_traceback(tb)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/backends/utils.py" in execute
  65.                 return self.cursor.execute(sql, params)
File "/home/grez/restenv/lib/python3.4/site-packages/django/db/backends/sqlite3/base.py" in execute
  485.         return Database.Cursor.execute(self, query, params)
Exception Type: IntegrityError at /snippets/
Exception Value: NOT NULL constraint failed: snippets_snippet.owner_id

答案似乎取决于Django REST框架版本。以下答案已在版本 3.2.4 和 3.10.3 上进行了测试。如果您使用这些版本和基于类的视图，则应输入：

serializer.save(owner=self.request.user)

而不是

serializer.save()

在 SnippetList.post（）方法中，使其如下所示：

def post(self, request, format=None):
    serializer = SnippetSerializer(data=request.data)
    if serializer.is_valid():
        serializer.save(owner=self.request.user)
        return Response(serializer.data, status=status.HTTP_201_CREATED)
    return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

函数 pre_create（）应从 SnippetList 类中排除。

我今晚正在浏览本教程并遇到了同样的错误。似乎本教程可能落后于实际框架的一个版本左右？无论如何，经过一些研究，我能够获得要保存的片段。

教程说要这样做的地方：

def perform_create(self, serializer):
    serializer.save(owner=self.request.user)

我切换到这个：

def pre_save(self, snip):
    snip.owner = self.request.user

似乎该方法不再存在或被调用perform_create因此owner永远不会被设置，因此我们看到的错误。我不确定我所做的是否是解决问题的正确方法，但它似乎有效！

这是我弄清楚上述内容的文档的链接：http://www.django-rest-framework.org/api-guide/generic-views/#genericapiview

您可以在 SnippedList 的 post 方法中更新 save（）参数：

def post(self, request, format=None):
    serializer = SnippetSerializer(data=request.data)
    if serializer.is_valid():
        serializer.save(owner=self.request.user)
        return Response(serializer.data, status=status.HTTP_201_CREATED)
    return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

perform_create在CreateModelMixin中，你的视图应该是泛型的子类。ListCreateAPIView

我有同样的问题。我发现我向SnippetSerializer中添加了一个perform_create方法，但它需要添加到SnippetList视图中，教程中有描述。

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