Python – When to split a child app into a new app

I’m creating a movie/TV related website: movies are called “titles”, so I have a title app to handle the operation of these contents. However, titles can also have genres and actors.

What is the best way to organize? Currently I have:

apps/titles (contains Title, and TitleGenre classes)
apps/titles/genres (contains Genre model class)

Is this the optimal solution? A sub-application of titles may even be necessary, as for whether genres converts similar types in the title application? Before diving in, I obviously want to start in the best possible way.

I’ll do something along these lines:

MyProject/
|- films/
   |- __init__.py
   |- urls.py
   |- models/
      |- __init__.py
      |- genre.py
      |- actor.py
      |- title.py
      |- actorrole.py //M2M through with actors and their roles in specific titles
   |- admin/
      |- __init__.py
      |- genre.py
      |- actor.py
      |- title.py
   |- views/
      |- __init__.py
      |- someview.py
|- myproject/
   |- __init__.py
   |- urls.py
   |- wsgi.py
   |- settings/
      |- __init__.py
      |- production.py
      |- staging.py
      |- local.py

3 or 4 models is not so much that I would spread it across several applications. But for organization, save the model and management classes in separate files and import them into the __init__.py of the folder

Important:

In your model, make sure that you include app_name in your internal meta class.

class Genre(models. Model):
    ...
    class Meta:
        app_label = _(u'films') #app's name
        ...

Ensure that all FKs are passed as strings and not as classes (helps avoid circular dependencies).

title = models. ForeignKey("films. Title")

Import in the correct order in your films/models/__init__.py to avoid circular dependencies.

from films.models.genre import Genre
from films.models.actor import Actor
from films.models.title import Title
from films.models.actorrole import ActorRole

Register each of your management classes in your films/admin/__init__.py

from django.contrib import admin
from lottery.models import Genre, Actor, Title
from lottery.admin.actor import ActorAdmin

admin.site.register(Actor, ActorAdmin)
...