REST Condition

1.0.3 verified Fri May 01 auth: no python

Rest Condition provides a simple, declarative way to compose complex permission checks for Django REST Framework views using logical operators (&, |, ~). Current version is 1.0.3, with infrequent updates.

pip install rest-condition

Common errors

error 'list' object has no attribute 'has_permission' ↓

cause Using a list of permission classes instead of a single condition instance.

fix

Use rest_condition classes: permission_classes = [And(IsAuthenticated, IsAdmin)] instead of [IsAuthenticated, IsAdmin]

error TypeError: __init__() takes 1 positional argument but 2 were given ↓

cause Calling a rest_condition class without parentheses, e.g., `And(IsAuthenticated, IsAdmin)` vs using `And` alone.

fix

Ensure you instantiate the condition: And(IsAuthenticated, IsAdmin)

error AttributeError: 'And' object has no attribute 'has_permission' ↓

cause Using an uninstantiated class reference in permission_classes, e.g., `permission_classes = [And]`.

fix

Instantiate: permission_classes = [And(IsAuthenticated)]

Warnings

gotcha rest_condition classes are not callable directly; they must be instantiated. For example, use `And(IsAuthenticated)` not `And`. ↓

fix Instantiate the condition: `permission_classes = [And(IsAuthenticated, IsAdmin)]`

gotcha Order of conditions matters: `And(cond1, cond2)` short-circuits on first False, `Or` short-circuits on first True. Unexpected results can occur if side effects exist. ↓

fix Ensure no side effects in permission checks, or be aware of evaluation order.

gotcha Permission classes used inside rest_condition must have `has_permission` or `has_object_permission` methods returning bool. Mixing with DRF's `SAFE_METHODS` pattern may cause confusion. ↓

fix Define custom permissions with explicit boolean returns.

Imports

rest_condition
```
from rest_condition import C, And, Or, Not
```
Correct import for the main composable permission classes.
rest_condition
wrong
```
from rest_condition import And, Or, Not, C
```
correct
```
from rest_condition import And, Or, Not
```
C is a shortcut for creating a condition from a custom permission class. It's not required for basic usage but often used.

Quickstart

Define a view with combined permission checks using logical operators. Placeholder permissions IsAdmin and IsOwner should be defined elsewhere.

from rest_framework.permissions import IsAuthenticated
from rest_condition import And, Or, Not
from rest_framework.views import APIView

class MyView(APIView):
    permission_classes = [And(IsAuthenticated, ~Or(IsAdmin, IsOwner))]
    def get(self, request):
        return Response({"message": "Hello"})