"""passbook expression Policy Models"""
from typing import Type
from django.db import models
from django.forms import ModelForm
from django.utils.translation import gettext as _
from passbook.policies.expression.evaluator import PolicyEvaluator
from passbook.policies.models import Policy
from passbook.policies.types import PolicyRequest, PolicyResult
class ExpressionPolicy(Policy):
"""Execute arbitrary Python code to implement custom checks and validation."""
expression = models.TextField()
def form(self) -> Type[ModelForm]:
from passbook.policies.expression.forms import ExpressionPolicyForm
return ExpressionPolicyForm
def passes(self, request: PolicyRequest) -> PolicyResult:
"""Evaluate and render expression. Returns PolicyResult(false) on error."""
evaluator = PolicyEvaluator(self.name)
evaluator.set_policy_request(request)
return evaluator.evaluate(self.expression)
def save(self, *args, **kwargs):
PolicyEvaluator(self.name).validate(self.expression)
return super().save(*args, **kwargs)
class Meta:
verbose_name = _("Expression Policy")
verbose_name_plural = _("Expression Policies")
