Graphene/Django突变返回null

Question

我在django应用程序中创建了以下模型：

class Post(models.Model):
title = models.CharField(max_length=125, unique=True)
slug_title = models.SlugField(max_length=255, unique=True)
body = models.TextField()
published_date = models.DateTimeField(auto_now_add=True)
author = models.ForeignKey(User, on_delete=models.CASCADE)
status = models.BooleanField(default=False)
class Meta:
ordering = ['-published_date']
def __str__(self):
return self.title

def save(self, *args, **kwargs):
self.slug_title = slugify(self.title)
super(Post, self).save(*args, **kwargs)

我希望以后能够使用API来执行POST/GET请求，所以我决定使用graphene-django。所有的东西都安装正确并且工作正常。

根据教程，我创建了如下schema.py文件：

# define schema
class PostType(DjangoObjectType):
class Meta:
model = Post
fields = ('title', 'body', 'author', 'published_date', 'status', 'slug_title')
class UserType(DjangoObjectType):
class Meta:
model = get_user_model()
class PostInput(graphene.InputObjectType):
title = graphene.String()
slug_title = graphene.String()
body = graphene.String()
author = graphene.Int()
published_date = graphene.DateTime()
status=graphene.Boolean()
class CreatePost(graphene.Mutation):
class Arguments:
input = PostInput(required=True)
post = graphene.Field(PostType)

@classmethod
def mutate(cls, root, info, input):
post = Post()
post.title = input.title
post.slug_title = input.slug_title
post.body = input.body
post.author = input.author
post.published_date = input.published_date
post.status = input.status
post.save()
return CreatePost(post=post)
class Query(graphene.ObjectType):
all_posts = graphene.List(PostType)
author_by_username = graphene.Field(UserType, username=graphene.String())
posts_by_author = graphene.List(PostType, username=graphene.String())
posts_by_slug = graphene.List(PostType, slug=graphene.String())

def resolve_all_posts(root, info):
return Post.objects.all()

def resolve_author_by_username(root, info, username):
return User.objects.get(username=username)

def resolve_posts_by_author(root, info, username):
return Post.objects.filter(author__username=username)

def resolve_posts_by_slug(root, info, slug):
return Post.objects.filter(slug_title=slug)
class Mutation(graphene.ObjectType):
create_post=CreatePost.Field()
schema = graphene.Schema(query=Query, mutation=Mutation)

查询部分按预期工作，但我的突变部分似乎不工作。当我试图创建一个突变时，我会得到以下结果：

{
"data": {
"create_post": {
"post": null
}
}
}

我创建了一个快速测试，看看当我运行突变时是否会输出任何错误，但那里的一切似乎都很好。

def test_mutation_1(self):
response = self.query(
'''
mutation {
createPost(input:{
title:"Test Title", 
body:"Test body", 
author:1, 
publishedDate:"2016-07-20T17:30:15+05:30", 
status:false
})
{
post {
title
}
}
}
'''
)
self.assertResponseNoErrors(response)

我没有收到错误消息。

任何帮助都将不胜感激！

Answer 1

错误：errors=[GraphQLError('Cannot assign "1": "Post.author" must be a "User" instance.'

解决方案：将我的CreatePost类更改为以下内容：

post.author = User.objects.get(pk=input.author_id)

代替：

post.author = input.author_id