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django internal code uses _base_manager instead of objects
There is also _default_manager
I'm more accustomed to using objects
What's the difference?
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A Manager is the interface through which database query operations are provided to Django models. At least one Manager exists for every model in a Django application. The way Manager classes work is documented in Making queries ; this document specifically touches on model options that customize Manager behavior.
Once you’ve created your data models, Django automatically gives you a database-abstraction API that lets you create, retrieve, update and delete objects. This document explains how to use this API.
To represent database-table data in Python objects, Django uses an intuitive system: A model class represents a database table, and an instance of that class represents a particular record in the database table. To create an object, instantiate it using keyword arguments to the model class, then call save () to save it to the database.
Finally, it’s important to note that the Django database layer is merely an interface to your database. You can access your database via other tools, programming languages or database frameworks; there’s nothing Django-specific about your database.
The difference between 'objects' and '_base_manager' is that you can replace 'objects' with custom manager, but '_base_manager' will be the default django.db.models.Manager instance anyway. In general, you should'n be using '_base_manager'. Sometimes Django itself needs to use '_base_manager' to be sure of it's behavior.
from django.db import models
class CommentManager(models.Manager):
pass
class Comment(models.Model):
...
objects = CommentManager()
print(type(Comment.objects)) #<class 'main.models.CommentManager'>
print(type(Comment._default_manager)) #<class 'main.models.CommentManager'>
print(type(Comment._base_manager)) #<class 'django.db.models.manager.Manager'>
To explain '_default_manager' I'll give one more simple example:
class Comment(models.Model):
...
custom_objects = CommentManager()
print(type(Comment._default_manager)) #<class 'main.models.CommentManager'>
print(type(Comment._base_manager)) #<class 'django.db.models.manager.Manager'>
print(type(Comment.objects)) #AttributeError: type object 'Comment' has no attribute 'objects'
So, is you set custom manager to model, it won't have 'objects' attribute, but it still will have '_default_manager'(your custom manager instance) and '_base_manager' - django.db.models.Manager instance.
Also be aware that there's a bug in Django source code related to managers according to my ticket: https://code.djangoproject.com/ticket/25897 I provided the patch to fix it, but it hasn't been applied yet.
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