Asserting for presence of added objects in Django ManyToMany relation

问题

I have the following model;

class Station(models.Model):
    name = models.CharField(max_length=50)
    address = models.TextField(default='')
    owner = models.ForeignKey(User,default='')
    members = models.ManyToManyField(User, related_name='members')

Now after the following code;

user1 = User.objects.create_user(username="username1",
                                     password="password1")
user1.save()
user2 = User.objects.create_user(username="username2",
                                     password="password2")
user2.save()
user3 = User.objects.create_user(username="username3",
                                     password="password3")
user3.save()
station = Station(name="somename",                            
                  address="someaddress",
                  owner=user1,
)
station.save()

station.members.add(user2,user3)

I want to assert that the added users are indeed there as the "members" of "Station"

Someone please tell me how

assert station.members == [user2,user3] doesn't fly. station.members actually is <Station: Station object>.members instead.

回答1:

station.members is a Manager, i.e. it is the accessor for queries on the related users. You need to actually perform a query: in this case, station.members.all().

回答2:

A few issues with your code, this is the output in my console:

>>> station.members
<django.db.models.fields.related.ManyRelatedManager object at 0x110774b10>

station.members is a ManyRelatedManager rather than a list of user2 and user3.

station.members.all() will return you a list of user2 and user3, but station.members.all() is a QuerySet instead of a list:

>>> type(station.members.all())
<class 'django.db.models.query.QuerySet'>

So doing assert station.members.all() == [user2, user3] will never be True.

来源：https://stackoverflow.com/questions/30208159/asserting-for-presence-of-added-objects-in-django-manytomany-relation

标签

django

many-to-many