Check for requires_context = True when calling validators

In encode/django-rest-framework#7062 the API for calling DRF validators
changed to require the caller to inspect the validator instance to
determine if the validator requires a second argument at call time.
Usage with DRF >=3.11.0 requires this support.

Author: bd808

rest_framework_friendly_errors/mixins.py

@@ -178,9 +178,15 @@ def _run_validator(self, validator, field, message, parent=None):
             if parent:
                 initial_data = self.initial_data[parent.field_name]
                 for data in initial_data:
-                    validator(data[field.field_name])
+                    if getattr(validator, 'requires_context', False):
+                        validator(data[field.field_name], field)
+                    else:
+                        validator(data[field.field_name])
             else:
-                validator(self.initial_data[field.field_name])
+                if getattr(validator, 'requires_context', False):
+                    validator(self.initial_data[field.field_name], field)
+                else:
+                    validator(self.initial_data[field.field_name])
         except (DjangoValidationError, RestValidationError) as err:
             err_message = err.detail[0] \
                 if hasattr(err, 'detail') else err.message