Django第二个M2M关系

Question

I have two models: User and Board.

class Board(models.Model):
    title = models.CharField(max_length=20, verbose_name=u'Название')
    members = models.ManyToManyField(to='user.User', related_name='boards', verbose_name=u'Участники')

And I want to get a list of users ids, which have at least one common board with current user. If I use this filter:

User.objects.filter(boards__members__id=self.request.user.id).values_list('id', flat=True)

It returns me

[1, 2, 6, 1, 2, 3]

And I expect this result. But when I use:

self.request.user.boards.all().values_list('members__id', flat=True)

It returns me a list, which contains only current user id.

[1, 1]

What happens?

UPD

I forgot one important thing: there is a function, which look like:

def has_related_value(obj, field, channel_val):
    filter_by_val = channel_val
    property_name, filter_by_val = field.split('__', 1)

    attr = getattr(obj, property_name)
    if hasattr(attr, 'all'):
        return getattr(obj, property_name).filter(**{filter_by_val: channel_val}).exists()

And it is roughly called such: has_related_value(self.request.user, 'boards__members__id', self.request.user.id) . Perhaps, I can change return getattr(obj, property_name).filter(**{filter_by_val: channel_val}).exists() to obj.__class__.objects.filter(pk=obj.pk, **{field: channel_val}).exists() , but i don't want to change this function. So, i try to find such "field" and "channel_val" values, that will be work. Also "channel_val" must be constant, so "field" - "boards__in" and "channel_val" - self.connection.user.boards.all() does not work.

Answer 1

It's the correct behavior because self.request.user refers to current user and that is why you are getting current user relationship objects. If you want entire User object model you need to use Django User Model to get results

Answer 2

Let's break this down a bit. First, you want to know what boards the current user belongs to:

boards = Board.objects.filter(members=self.request.user)

Then, you want to know all user ids that belong to those boards (there may be duplicates, so use distinct() ):

User.objects.filter(
    boards__in=boards
).distinct().values_list('id', flat=True)

You could mix those together:

User.objects.filter(
    boards__in=Board.objects.filter(members=self.request.user)
).distinct().values_list('id', flat=True)

Now, the only thing you need to worry about is that request.user.id may be in the results. You could remove that using an exclude clause:

User.objects.exclude(
    id=self.request.user.id
).filter(
    boards__in=Board.objects.filter(members=self.request.user)
).distinct().values_list('id', flat=True)