如何将值添加到 ManyToManyField

Question

我有以下模型，它有一个名为 who_can_see 的字段，我不知道如何向该字段添加数据，也不知道数据的类型（字典、数组...）

#modles.py
class Author(models.Model):
    name = models.CharField(max_length=200)
    added_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    created_date = models.DateTimeField(default=timezone.now)

    def __str__(self):
        return self.name


class Book(models.Model):
    title = models.CharField(max_length=200)
    description = models.CharField(max_length=300)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)
    added_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    created_date = models.DateTimeField(default=timezone.now)
#????
    who_can_see = models.ManyToManyField(
        settings.AUTH_USER_MODEL, related_name='tweet_user', blank=True)

    def __str__(self):
        return self.title

• 你可以在这里看到我在哪里添加????，我正在尝试who_can_see= [author, payload["who_can_see"]]，所以我希望字段who_can_see 是一个数组，但是当我发出POST 请求时，我得到500 错误

@api_view(["POST"])
@csrf_exempt
@permission_classes([IsAuthenticated])
def add_book(request):
    print({"request.data": request.data})
    payload = request.data
    user = request.user
    try:
        author = Author.objects.get(id=payload["author"])
        book = Book.objects.create(
            title=payload["title"],
            description=payload["description"],
            added_by=user,
            author=author,
            # who_can_see= [author, payload["who_can_see"]]  # ????
        )
        serializer = BookSerializer(book)
        return JsonResponse({'books': serializer.data}, safe=False, status=status.HTTP_201_CREATED)
    except ObjectDoesNotExist as e:
        return JsonResponse({'error': str(e)}, safe=False, status=status.HTTP_404_NOT_FOUND)
    except Exception:
        return JsonResponse({'error': 'Something terrible went wrong'}, safe=False, status=status.HTTP_500_INTERNAL_SERVER_ERROR)

Answer 1

您应该首先创建图书，然后添加who_can_see 属性。就像documentation上的例子一样

你的情况几乎很好。它看起来像：

def add_book(request):
    print({"request.data": request.data})
    payload = request.data
    user = request.user
    try:
        author = Author.objects.get(id=payload["author"])
        book = Book.objects.create(
            title=payload["title"],
            description=payload["description"],
            added_by=user,
            author=author,
        )
        book.who_can_see.add(author) 
        serializer = BookSerializer(book)
        return ...

编辑：我意识到您的模型与您的观点不一致。为什么将 who_can_see 链接到 AUTH_USER_MODEL 而不是 Author ？根据您的观点，您的模型应该是：

who_can_see = models.ManyToManyField(Author,related_name='tweet_user', blank=True)