Django：禁止直接赋值给多对多集合的前端。使用 user.set() 代替

Question

我看到这是一个常见问题，我理解的想法是，除非先创建它，否则不能将多对多相加。我已经看到了多种解决方案，但不确定使用哪一种。

Models.py

class Concert(models.Model):
    venue = models.CharField(max_length=200, null=True)
    concertid = models.CharField(max_length = 200, null=False, default='didnotsaveproperly') 
    date = models.DateField(null=True) 
    city = models.CharField(max_length=100, null=True)
    country = models.CharField(max_length=200, null=True)
    user = models.ManyToManyField(USER_MODEL, related_name="concerts", null=True) 
    song = models.ManyToManyField("Song", blank=True, null=True)

    def __str__(self): 
        return str(self.concertid) + " " + str(self.venue) + " " + str(self.date)

Views.py

def log_concert_and_song(request, concertdict):
    if request.method == "POST":
        Concert_save = Concert(
        concertid=concertdict['id'], 
        date=concertdict['eventDate'], 
        venue=concertdict['venue'], 
        city=concertdict['city'], 
        country=concertdict['country'], 
        user = request.user
        )
 
    Concert_save.save()

我应该使用用户模型吗？

Answer 1

您可以使用 add 添加到 Many-to-Many 关系阅读文档：https://docs.djangoproject.com/en/4.0/topics/db/examples/many_to_many/#many-to-many-relationships

def log_concert_and_song(request, concertdict):
if request.method == "POST":
    Concert_save = Concert(
    concertid=concertdict['id'], 
    date=concertdict['eventDate'], 
    venue=concertdict['venue'], 
    city=concertdict['city'], 
    country=concertdict['country'], 
    )
    Concert_save.save()

    Concert_save.user.add(request.user)

或如错误所说：

list_of_users = [request.user,]
Concert_save.user.set([list_of_users])

Django：禁止直接赋值给多对多集合的前端。使用 user.set() 代替

Django: Direct assignment to the forward side of a many-to-many set is prohibited. Use user.set() instead

django

many-to-many

django-models