title: Common app_label for all the models in Django
body: <p>I have many classes in <code>models.py</code> something like:</p>
  
  <pre><code>class SomeClass1(BaseModel):
      question = models.ForeignKey(Question)
      image = models.ForeignKey(Image)
  
  class SomeClass2(BaseModel):
      question = models.ForeignKey(Question)
      option_text = models.TextField()
  </code></pre>
  
  <p>Now, I want to add <code>app_label = 'my_app_label1'</code> to all of these classes, something like this:</p>
  
  <pre><code>class SomeClass1(BaseModel):
      question = models.ForeignKey(Question)
      image = models.ForeignKey(Image)
      class Meta:
          app_label = 'my_app_label1'
  </code></pre>
  
  <p>But since there are many classes, so instead of adding <code>app_label = 'my_app_label1'</code> to all the classes, I'm adding <code>app_label = 'my_app_label1'</code> to the BaseModel, like this:</p>
  
  <pre><code>class BaseModel(models.Model):
      """
      For future abstraction.
      """
      class Meta:
          app_label = 'ques_app_data'
  </code></pre>
  
  <p>After which I'm getting this error:</p>
  
  <pre><code>myapp.SomeClass1.basemodel_ptr: (fields.E300) Field defines a relation with model 'BaseModel', which is either not installed, or is abstract.
  </code></pre>
  
  <p>Can anyone please explain how to solve this ?</p>