title: Deleting Object from QuerySet List in Django with ManyToMany relationship
body: <p>I am having trouble deleting an object from a list of objects while using <code>ForeignKey</code> and <code>ManyToMany</code> relationships in Django.</p>
  
  <p>Here is the models I have set up for an Item, List, and the Order (an intermediary model).</p>
  
  <pre><code>class Item(models.Model):
      title_english = models.CharField(max_length=250)
      url = models.CharField(max_length=250)
      img_url = models.CharField(max_length=250)
  
      def __unicode__(self):
          return self.title_english
  
  class List(models.Model):
      slides = models.ManyToManyField(Item, through='Order')
      size = models.PositiveIntegerField(default=0)
  
      def incrementSize(self):
          self.size = self.size+1
  
      def __unicode__(self):
          return "List: " + str(self.slides.all())
  
  class Order(models.Model):
      item = models.ForeignKey(Item, on_delete=models.CASCADE)
      list = models.ForeignKey(List, on_delete=models.CASCADE)
      index = models.PositiveIntegerField()
  
      def __unicode__(self):
          return str(index) + ": " + str(self.item)
  
      def appendItemToList(self, item, list):
          self.item = item
          self.list = list
          self.index = list.size
          list.incrementSize()
  </code></pre>
  
  <p>I am adding objects to the list (created dynamically from existing objects), through the view like so:</p>
  
  <pre><code>def AddItem(request, pk):
      sourceObj = SourceObject.objects.get(pk=pk)
      lst = List.objects.all()
      if not lst:
          lst = List()
          lst.save()
      else:
          lst = lst[0]
      item = Item(title_english=sourceObj.name_english,  url=sourceObj.slug, img_url=sourceObj.media)
      item.save()
      order = Order()
      order.appendItemToList(item, lst)
      order.save()
      lst.save()
      return redirect("some_url")
  </code></pre>
  
  <p>Now my issue is, deleting an item added to <code>list</code>. I am having trouble understanding how I can access the target object.</p>
  
  <pre><code>def RemoveItem(request, pk):
      lst = List.objects.all()
      lst.delete() #deletes the entire list
      #how do I access the target object from here to delete it
      return redirect("some_url")
  </code></pre>
  
  <p>I read through the Django docs referring to "Following relationships backwards" here: <a href="https://docs.djangoproject.com/en/dev/topics/db/queries/#backwards-related-objects" rel="nofollow">https://docs.djangoproject.com/en/dev/topics/db/queries/#backwards-related-objects</a></p>
  
  <p>But I couldn't find a solution that works.</p>
  
  <p>Note: I'm using Django 1.5 and Python 2.7</p>