How does Django know which model manager to use?

Question

So I am interested in using the example code below in a Django project, but am puzzled when trying to understand how I would call one model manager explicitly.

class AuthorManager(models.Manager):
    def get_queryset(self):
        return super(AuthorManager,    self).get_queryset().filter(role='A')

class EditorManager(models.Manager):
    def get_queryset(self):
        return super(EditorManager, self).get_queryset().filter(role='E')

class Person(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    role = models.CharField(max_length=1, choices=(('A', _('Author')), ('E', _('Editor'))))
    people = models.Manager()
    authors = AuthorManager()
    editors = EditorManager()

I know the view calls the models and the models calls the model manager, but its kind of confusing to me. Can I specify which view calls which manager or does the model take care of that implicitly through some other way?

Answer 1

As per the documentation, you can call either model manager from your views with Person.authors.get_queryset or Person.editor.get_queryset. Additionally, you can pass data back to either manager. For example:

In views:

data = {
    'first_name' : request.POST['first_name'],
    'last_name' :request.POST['last_name'],
    'email' : request.POST['email'],
  }
author = Person.authors.new_author(data)
editor = Person.editor.new_editor(data)

The "author"/"editor" variable above will become whatever your models passes back.

Obviously, you would want to define new methods in your managers. E.g.

In models:

class AuthorManager(models.Manager):
    def new_author(self):
        Person.authors.create(...)

class EditorManager(models.Manager):
    def new_editor(self):
        Person.editors.create(...)

You can choose to have your models pass back whatever user info you need to your views.