[英]Django/Django Rest Framework - How do I allow model serializer to set model's foreign key field to null?
[英]How do I add a foreign key field in a post method for Django Rest Framework
如果我是菜鳥,我真的很抱歉,但是如何使用我的 post 方法添加外鍵字段。 我需要提及博客文章,即對文章發表評論的用戶。 但是,帖子和用戶/所有者都是我模型中的外鍵字段。 對於 Postman,它會給出 Django 完整性錯誤。
模型.py
class Comment(models.Model) :
text = models.TextField(
validators=[MinLengthValidator(3, "Comment must be greater than 3 characters")]
)
post = models.ForeignKey(Post, on_delete=models.CASCADE)
owner = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
# Shows up in the admin list
def __str__(self):
return (self.post.title)
序列化程序.py
class CommentSerializer(serializers.ModelSerializer):
owner = serializers.StringRelatedField()
post = serializers.StringRelatedField()
class Meta:
model = Comment
fields = ['id', 'text', 'created_at', 'post', 'owner']
視圖.py
class CommentViewSet(viewsets.ModelViewSet):
serializer_class = CommentSerializer
permission_classes = [permissions.IsAuthenticatedOrReadOnly]
queryset = Comment.objects.all()
filter_backends = [DjangoFilterBackend]
filter_fields = ['post']
完整的錯誤跟蹤:
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/sqlite3/base.py", line 413, in execute
return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: NOT NULL constraint failed: api_comment.owner_id
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/core/handlers/exception.py", line 47, in inner
response = get_response(request)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/core/handlers/base.py", line 181, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
return view_func(*args, **kwargs)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/viewsets.py", line 125, in view
return self.dispatch(request, *args, **kwargs)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/views.py", line 509, in dispatch
response = self.handle_exception(exc)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/views.py", line 469, in handle_exception
self.raise_uncaught_exception(exc)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
raise exc
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/views.py", line 506, in dispatch
response = handler(request, *args, **kwargs)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/mixins.py", line 19, in create
self.perform_create(serializer)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/mixins.py", line 24, in perform_create
serializer.save()
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/serializers.py", line 205, in save
self.instance = self.create(validated_data)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/rest_framework/serializers.py", line 939, in create
instance = ModelClass._default_manager.create(**validated_data)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/query.py", line 447, in create
obj.save(force_insert=True, using=self.db)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/base.py", line 753, in save
self.save_base(using=using, force_insert=force_insert,
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/base.py", line 790, in save_base
updated = self._save_table(
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/base.py", line 895, in _save_table
results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/base.py", line 933, in _do_insert
return manager._insert(
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/query.py", line 1254, in _insert
return query.get_compiler(using=using).execute_sql(returning_fields)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/models/sql/compiler.py", line 1397, in execute_sql
cursor.execute(sql, params)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/utils.py", line 98, in execute
return super().execute(sql, params)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/utils.py", line 66, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/utils.py", line 75, in _execute_with_wrappers
return executor(sql, params, many, context)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/utils.py", line 90, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "/Users/syedzayyanmasud/Desktop/blog/venv/lib/python3.9/site-packages/django/db/backends/sqlite3/base.py", line 413, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: NOT NULL constraint failed: api_comment.owner_id
您需要如下更改序列化程序
from rest_framework.fields import CurrentUserDefault
class CommentSerializer(serializers.ModelSerializer):
owner = serializers.StringRelatedField()
post = serializers.StringRelatedField()
def create(self, validated_data):
obj = Comment(**validated_data)
obj.owner = CurrentUserDefault()
obj.save()
return obj
class Meta:
model = Comment
fields = ['id', 'text', 'created_at', 'post', 'owner']
您需要導入所需的導入。
參考: https://www.django-rest-framework.org/api-guide/validators/#currentuserdefault
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