Asserting for presence of added objects in Django ManyToMany relation

Question

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.

You are trying to test a Django models and not your own, is it really useful ? — Charlesthk, May 13 '15 at 07:31

score 0 · Accepted Answer · edited May 13 '15 at 08:22

0

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().

edited May 13 '15 at 08:22

Mathieu Dhondt

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answered May 13 '15 at 07:42

Daniel Roseman

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Thank you. Needed just to properly read Django's documentation actually :D. – Afzal S.H. May 13 '15 at 07:44
Mr.Roseman please check out http://stackoverflow.com/questions/30237820/making-a-link-pass-a-post-method-in-django :) – Afzal S.H. May 14 '15 at 12:54

score 0 · Answer 2 · answered May 13 '15 at 07:43

0

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.

answered May 13 '15 at 07:43

Cheng

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No but I can check `assert user2 in station.members.all()` and `assert user3 in station.members.all()` – Afzal S.H. May 13 '15 at 07:50
@afzal_SH I know you can do that. Just want to point out that '==' will not work. Hope this helps :) – Cheng May 13 '15 at 07:54
Actually I needed just to read Django's documentation on ManyToMany relation a little proper. I got the answer doing that just after I posted but by the time I got here Daniel Roseman had the answer :). In case you din notice I was originally trying to do `assert station.members == [user2, user3]` Not even `assert station.members.all() == [user2, user3]` :) – Afzal S.H. May 13 '15 at 08:15
1

@afzal_SH I am fully aware that you are doing station.members == instead of station.members.all() ==. But, it is quite obvious that you are going to do `assert station.members.all() == [user2, user3]` next. I have no intention to argue with you. As long as you get what you need great. – Cheng May 13 '15 at 08:18
@:D Okay! Wasn't really arguing though! – Afzal S.H. May 13 '15 at 17:01

Asserting for presence of added objects in Django ManyToMany relation

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