django model object filter from 2 different model-CodePudding

So I am trying to filter comments made by a specific user within a specific station.

First I have a model named comment and it has a relationship with the post.

class Comment(Votable):
    post = models.ForeignKey(Post, related_name='comments', on_delete=models.CASCADE)
    author = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='comments_authored', on_delete=models.CASCADE, blank=True)
    text = RichTextUploadingField(blank=True, null=True)
    parent = models.ForeignKey('self', related_name='children', null=True, blank=True, on_delete=models.PROTECT)

It's pretty easy to filter just based on author.

And then I have the model for post:

class Post(Votable):
    title = models.CharField(max_length=200, unique=False)
    submitter = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='posts_submitted', on_delete=models.CASCADE)
    url = models.URLField('URL', max_length=200, null=True, blank=True)
    text = RichTextUploadingField(blank=True, null=True)

    def children(self):
        return self.comments.filter(parent=None)
    def __str__(self):
        return self.title

    def save(self, *args, **kwargs): # new
        if not self.post_slug:
            self.post_slug = slugify(str(self.title) str(self.pk))
        return super().save(*args, **kwargs)

The post model has a relationship with the station, which I use StationPost to establish the relationship. So a station can have many posts:

class StationPost(BaseModel):
    station = models.ForeignKey('Station', related_name='posts_set', on_delete=models.CASCADE)
    post = models.ForeignKey('Post', related_name='station', on_delete=models.CASCADE)
    class Meta: unique_together = ['station', 'post']

And in case of any confusion, here is the model for station

class Station(BaseModel): #this is to add the station for each posts:
    alphanumeric = RegexValidator(r'^[0-9a-zA-Z]*$', 'Only alphanumeric characters are allowed.')
    station_name=models.CharField(max_length=19,validators=[alphanumeric], unique=True)
    creator = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='station_creator', on_delete=models.CASCADE)
    text = models.TextField(max_length=200, default='brief sentence to introduce your space')
    posts = models.ManyToManyField('Post', related_name='stations', blank=True, through='StationPost')


    def __str__(self):
        return self.station_name

    def save(self, *args, **kwargs): # new
        if not self.slug:
            self.slug = slugify(self.station_name)
        return super().save(*args, **kwargs)

    class Meta:
        ordering = [('station_name'), ]

Now I want to filter out comment objects such as the author is the user and the post belong to the specific station.

CodePudding user response：

You can traverse the relationship from comment -> post -> station post -> station like this:

Comment.objects.filter(
    author=request.user,
    post__station__station=1, # or a station object
).distinct()