Django queryset of articles by authors the user is following

Question

I have two models

class Account(AbstractBaseUser, PermissionsMixin):
    followers = models.ManyToManyField(
        'Account', related_name='followers',
        blank=True,
    )
    following = models.ManyToManyField(
        'Account', related_name='following',
        blank=True,
    )

and

class Article(models.Model):
    author = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
    )

I'm writing an application where users subscribe to each other and create articles.

How can I make a request to receive all the articles from those to whom I am subscribed? I'm trying to do something like: (pseudo-code)

user = self.get_object()
articles = Article.objects.filter(author=user.followers.all())

But I know that this is not right

If a user is `following` you, then that user is one of your `followers`, hence by introducing two relations, you introduce *data duplication* which is typically a bad idea. — Willem Van Onsem, May 23 '18 at 10:12

score 4 · Accepted Answer · answered May 23 '18 at 10:04

4

You can get list of following first, and then filter articles based on this list using __in:

user = self.get_object()
following = user.following.values_list('id', flat=True)
articles = Article.objects.filter(author_id__in=following)

answered May 23 '18 at 10:04

neverwalkaloner

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1

Yes, it seems this is what you need, thank you very much!) – woe-dev. May 23 '18 at 10:31

Alasdair · Answer 2 · 2018-05-23T10:35:53.653

3

You don't need two many-to-many fields.

For example, you can remove the followers many-to-many field, then get the followers for an account by using the reverse relationship of the following field.

class Account(AbstractBaseUser, PermissionsMixin):
    following = models.ManyToManyField(
        'Account', 
        related_name='followers',
        blank=True,
    )

Then you can use the double underscore notation to filter on the many-to-many field:

articles = Article.objects.filter(author__followers=user)

edited May 23 '18 at 10:35

answered May 23 '18 at 10:06

Alasdair

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In my case, this returns an empty query. Excuse me, this does not suit me, but thank you for responding) – woe-dev. May 23 '18 at 10:32
I think I might have used the wrong query. Try `author__followers=user` instead. – Alasdair May 23 '18 at 10:36
and what is the difference? – woe-dev. May 23 '18 at 10:44
`author__followers=user` returns articles where the user follows the author of the article. `author__following=user` returns articles where the author follows the user. – Alasdair May 23 '18 at 10:46

score 0 · Answer 3 · answered May 23 '18 at 11:06

You might want to split up followers and following fields into two classes. (PseudoCode)

class Following():
    author_id = models.foreignkey('Author')
    following_authors = models.integerfield('Following_Authors')

Loop into all authors you are following and append to a list. Of course, your Articles should have an article field that have their articles posted.

AuthorOfArticle = Author.objects.get(author='author to get all following')

FollowingAuthorsObj = Following.objects.filter(author=AuthorOfArticle.author) #get all the authors you are following.

ArticlesOfAuthor=[] #create a list variable
for authors in FollowingAuthorsObj: #loop through all you are following
    ArticlesOfAuthor.append(Article.objects.filter(author=authors[0].author)) 
#save it to a list of all articles.

Hope this helps.

Django queryset of articles by authors the user is following

3 Answers3