Public methods

The TypedPermsModelMixin class adds 3 methods to the inherited class. They're described below.

Model definition used on examples

All of the code examples that uses these methods assumes the following model definition:

polls/models.py

from typing import Annotated, Literal
from django.db import models
from django_typed_perms import TypedPermsModelMixin, get_choices_from_type_hint

QuestionCustomPermsT = (
    Annotated[Literal["publish_question"], "Publish Question"]
    | Annotated[Literal["clear_votes"], "Clear Votes"]
)

class Question(TypedPermsModelMixin[QuestionCustomPermsT], models.Model):
    class Meta:
        permissions = get_choices_from_type_hint(QuestionCustomPermsT)

user_has_permission

This method is used to check a given user has the permission to do some action on that specific Model class or object. You can use this method as a type-safe replacement for user.has_perm method from django.contrib.auth.models.AbstractUser. The key difference, is that since you'll be using a specific class to check permissions for, then you only be able to check for an action of that specific class.

Imagine the following permission check, we want to check if the user has permission to view the Question objects. This is a default permission of any Django model. So, using the user.has_perm method, you would do the following:

polls/views.py

def get_polls(request):
    if not request.user or not request.user.has_perm("polls.view_question"):
        # Raise an error, missing permissions
        ...

If you have ever done a Django project before, you recognize this pattern. And you know this can get really annoying, if you do some easy mistakes, like:

• Don't checking for a None value on request.user (Some AuthenticationBackend could've assigned None as value), and that would result on a TypeError.
• Mispelling the permission codename (that is {app_name}.{action}_{model_name}) on entirety, or any of its pieces. This would result on a possible false positive.
• This is repetitive, and not developer-friendly.

Now, let's do the same permission check using the user_has_permission method.

polls/views.py

from polls.models import Question

def get_polls(request):
    if not Question.user_has_permission(request.user, "view"):
        # Raise an error, missing permissions
        ...

The same result, but way less things to type, and to make a mistake. When using this method, you don't have to: * Worry about checking request.user for a None value; * Worry about mispelling the exact permission codename, or the app_name, or the action name, or the model_name. If you're using mypy you'll get an error if you provide a invalid action.

method signature

This method requires 2 positional/keyword arguments, they are: * user: An user-like object or None. Meaning that this object must have the has_perm method. * action: The name of the action to check permission against. This is either one of the Django's default permission, such as add, change, delete, or view.

It also optionally accepts a 3rd argument, the obj to check the permission against, we don't do anything with this argument, its directly passed to the user.has_perm method.

user_has_permissions

This method is essentially the same as the method, above, the only difference is that instead of calling user.has_perm, it calls user.has_perms with the provided Sequence of actions provided (such as tuple or a list).

polls/views.py

def get_polls(request):
    if not Question.user_has_permissions(request.user, ("view", "add")):
        # Raise an error, missing permissions
        ...

get_action_permission_name

This method can be used to retrieve the full qualified name of a permission, that can be used on user.has_perm call, for example. It accepts a single argument: action that is one of the Django's default permissions or any of the custom permissions provided on the mixin. This method is used internally by the methods user_has_permission and user_has_permissions to build the full permission name. Example:

polls/views.py

def get_polls(request):
    if not request.user not request.user.has_perm(Question.get_action_permission_name("view")):
        # Raise an error, missing permissions
        ...

This is the exact same of typing the full permission codename, such as:

polls/views.py

def get_polls(request):
    if not request.user not request.user.has_perm("polls.view_question"):
        # Raise an error, missing permissions
        ...