policies/expression: add pb_log function to debug

passbook/policies/expression/evaluator.py

@@ -46,6 +46,11 @@ class Evaluator:
         """Check if `user` is member of group with name `group_name`"""
         return user.groups.filter(name=group_name).exists()
 
+    @staticmethod
+    def jinja2_log(message, **kwargs):
+        """Output debug log to console"""
+        return LOGGER.debug("Expression log", _m=message, **kwargs)
+
     def _get_expression_context(
         self, request: PolicyRequest, **kwargs
     ) -> Dict[str, Any]:
@@ -53,6 +58,7 @@ class Evaluator:
         # update passbook/policies/expression/templates/policy/expression/form.html
         # update docs/policies/expression/index.md
         kwargs["pb_is_group_member"] = Evaluator.jinja2_func_is_group_member
+        kwargs["pb_log"] = Evaluator.jinja2_log
         kwargs["pb_logger"] = get_logger()
         if request.http_request:
             kwargs["pb_is_sso_flow"] = request.http_request.session.get(
@@ -88,7 +94,7 @@ class Evaluator:
             if isinstance(result, (list, tuple)) and len(result) == 2:
                 return PolicyResult(*result)
             if result:
-                return PolicyResult(result)
+                return PolicyResult(bool(result))
             return PolicyResult(False)
         except UndefinedError as exc:
             return PolicyResult(False, str(exc))