title: Python Django - Models: for loop in query/filter
body: <p>so i want to do a query where a field equals a property of an object in a for loop. Here is a working sample/example using sqlAlchemy: </p>
  
  <pre><code>you =   session.query(Users).filter_by(id=login_session['userid']).first()
  
  friends = session.query(Friends).filter_by(user_id=you.id).all()
  
  dashboard = session.query(Markers).filter(Markers.owner.in_([f.friend_id for f in friends)]).all()
  </code></pre>
  
  <p>How would i do this in django?</p>
  
  <p>Here is what i tried:</p>
  
  <pre><code>you = Accounts.objects.get(uname = request.session['username'])
  
  following = Follows.objects.filter(userid=you.id)
  
  POSTS = Posts.objects.filter(ownerid = [f.follow_id for f in following])
  </code></pre>
  
  <p>and this is what i got:</p>
  
  <pre><code>Traceback:
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\core\handlers\base.py" in get_response
    149.                     response = self.process_exception_by_middleware(e, request)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\core\handlers\base.py" in get_response
    147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\utils\decorators.py" in _wrapped_view
    149.                     response = view_func(request, *args, **kwargs)
  
  File "C:\Users\waite-ryan-m\Desktop\epsity\webapp\views.py" in profileMain
    102.             POSTS = Posts.objects.filter(ownerid = [f.follow_id for f in following])
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\manager.py" in manager_method
    122.                 return getattr(self.get_queryset(), name)(*args, **kwargs)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\query.py" in filter
    790.         return self._filter_or_exclude(False, *args, **kwargs)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\query.py" in _filter_or_exclude
    808.             clone.query.add_q(Q(*args, **kwargs))
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\sql\query.py" in add_q
    1243.         clause, _ = self._add_q(q_object, self.used_aliases)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\sql\query.py" in _add_q
    1269.                     allow_joins=allow_joins, split_subq=split_subq,
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\sql\query.py" in build_filter
    1203.             condition = self.build_lookup(lookups, col, value)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\sql\query.py" in build_lookup
    1099.                 return final_lookup(lhs, rhs)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\lookups.py" in __init__
    19.         self.rhs = self.get_prep_lookup()
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\lookups.py" in get_prep_lookup
    57.         return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\fields\__init__.py" in get_prep_lookup
    1860.         return super(IntegerField, self).get_prep_lookup(lookup_type, value)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\fields\__init__.py" in get_prep_lookup
    744.             return self.get_prep_value(value)
  
  File "C:\Users\waite-ryan-m\Desktop\WPython\WinPython-64bit-2.7.12.1Zero\python-2.7.12.amd64\lib\site-packages\django\db\models\fields\__init__.py" in get_prep_value
    1854.         return int(value)
  
  Exception Type: TypeError at /main/
  Exception Value: int() argument must be a string or a number, not 'list'
  </code></pre>
  
  <p>My models:</p>
  
  <pre><code>class Accounts(models.Model):
  
      uname = models.CharField(max_length = 20, default = '')
      displayname = models.CharField(max_length = 30, default = '')
      email = models.CharField(max_length = 50, default = '')
      pswrd = models.CharField(max_length = 50, default = '')
      provider = models.CharField(max_length = 20, default = '')
      provider_id = models.CharField(max_length = 100, default = '')
      avi = models.CharField(max_length = 500, default = '/static/img/anon2.png')
      background = models.CharField(max_length = 500, default = '/static/img/bg-default.jpg')
      gender = models.CharField(max_length = 25, default = '')
      phone = models.CharField(max_length = 25, default = '')
  
      type = models.CharField(max_length = 20, default = '')
      status = models.CharField(max_length = 9, default = 'public')
      # status: either public, private or deleted
  
      official = models.IntegerField(default = 0)
      # official: 1 = True | 0 = False
  
      interests = models.CharField(max_length = 1725, default = '')
      seeking = models.CharField(max_length = 1725, default = '')
  
      bio_desc = models.CharField(max_length = 150, default = '')
      bio_link = models.CharField(max_length = 150, default = '')
      #bio_link_name = models.CharField(max_length = 100, default = '')
  
      date_created = models.DateField( default = datetime.datetime.now )
      last_active = models.DateField(auto_now=True)
  
      @property
      def serialize(self):
           # Returns Data Object In Proper Format
          return {
              'userid': self.id,
              'uname': self.uname,
              'displayname': self.displayname,
              'avi': self.avi,
              'status': self.status,
              'background': self.background,
          }
  
      @property
      def get_bio(self):
           # Returns Data Object In Proper Format
          return {
              'desc': self.bio_desc,
              'link': self.bio_link,
              #'linkName': self.bio_link_name,
          }
  
      @property
      def get_info(self):
           # Returns Data Object In Proper Format
          return {
              'interests': self.interests,
              'seeking': self.seeking,
              #'linkName': self.bio_link_name,
          }
  
      class Meta:
          db_table = "accounts"
  
  # --- #
  
  class Follows(models.Model):
  
      userid = models.IntegerField(blank = False, default = 0)
      user_rel = models.ForeignKey(Accounts, default = 0, related_name = "user_rel")
  
      follow_id = models.IntegerField(blank = False, default = 0)
      follow_rel = models.ForeignKey(Accounts, default = 0, related_name = "follow_rel")
  
      date_created = models.DateField( default = datetime.datetime.now )
  
      @property
      def serialize(self):
           # Returns Data Object In Proper Format
          return {
              'fid': self.id,
  
              'userid': self.userid,
              'user': self.user_rel.serialize,
              'followid': self.follow_id,
              'follow': self.follow_rel.serialize,
              'date_created': self.date_created
              #'linkName': self.bio_link_name,
          }
  
      class Meta:
          db_table = "follows"
  
  # ---
  
  class Posts(models.Model):
  
      OwnerType = (
          ('Account', 'Account'),
          ('Group', 'Group'),
      )
  
      PostTypes = (
          ('Text', 'Text'),
          ('Photo', 'Photo'),
          ('Audio', 'Audio'),
          ('Video', 'Video'),
      )
  
      ownerid = models.IntegerField(blank = False, default = 0)
      owner_type = models.CharField(choices = OwnerType, blank = False, default = '', max_length = 50)
  
      title = models.CharField(max_length = 500, default = '')
      contents = models.CharField(max_length = 500, default = '')
      link = models.CharField(max_length = 500, default = '')
  
      attachment = models.CharField(max_length = 500, default = '')
      attachment_type = models.CharField(max_length = 500, default = '')
  
      post_type = models.CharField(max_length = 20, choices = PostTypes, default = '')
      status = models.CharField(max_length = 20, default = 'public') # either public, private, or deleted
  
      date_created = models.DateField( default = datetime.datetime.now )
      last_active = models.DateField(auto_now=True)
  
      @property
      def serialize(self):
          return {
              'p_id': self.id,
  
              'ownerid': self.ownerid,
              'owner': returnModelSerialized( self.owner_type , self.ownerid ),
              'owner_type': self.owner_type,
              'title': self.title,
              'contents': self.contents,
              'attachment': self.attachment,
              'attachment_type': self.attachment_type,
              'link': self.link,
              'post_type': self.post_type,
              'status': self.status,
              'date_created': self.date_created,
              'last_active': self.last_active
          }
  
      class Meta:
          db_table = "posts"
  
  # ---
  </code></pre>