From 03bc732b5c542cf1ab3d4a556651954bf54b9427 Mon Sep 17 00:00:00 2001
From: Stephen Finucane <stephen@that.guru>
Date: Sat, 6 Oct 2018 17:29:50 +0100
Subject: [PATCH] Populate error.message with error.params

Exceptions like ValidationError can include an optional 'params'
argument that contains parameters to format the 'message' argument with.
Handle these.

Signed-off-by: Stephen Finucane <stephen@that.guru>
Fixes: 78febd1 ("Rework validation, add queryset filter method (#788)")
---
 django_filters/utils.py |  3 ++-
 tests/test_utils.py     | 18 +++++++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/django_filters/utils.py b/django_filters/utils.py
index 781d3f436..53e29bcb4 100644
--- a/django_filters/utils.py
+++ b/django_filters/utils.py
@@ -317,7 +317,8 @@ def translate_validation(error_dict):
     from rest_framework.exceptions import ValidationError, ErrorDetail
 
     exc = OrderedDict(
-        (key, [ErrorDetail(e.message, code=e.code) for e in error_list])
+        (key, [ErrorDetail(
+            e.message % (e.params or {}), code=e.code) for e in error_list])
         for key, error_list in error_dict.as_data().items()
     )
 
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 2d89a9a54..e944ec427 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -8,7 +8,7 @@
 from django.utils.functional import Promise
 from django.utils.timezone import get_default_timezone
 
-from django_filters import FilterSet
+from django_filters import FilterSet, ModelMultipleChoiceFilter
 from django_filters.exceptions import FieldLookupError
 from django_filters.utils import (
     MigrationNotice,
@@ -511,6 +511,13 @@ class Meta:
             model = Article
             fields = ['id', 'author', 'name']
 
+    class G(FilterSet):
+        author = ModelMultipleChoiceFilter(queryset=User.objects.all())
+
+        class Meta:
+            model = Article
+            fields = ['id', 'author', 'name']
+
     def test_error_detail(self):
         f = self.F(data={'id': 'foo', 'author': 'bar', 'name': 'baz'})
         exc = translate_validation(f.errors)
@@ -520,6 +527,15 @@ def test_error_detail(self):
             'author': ['Select a valid choice. That choice is not one of the available choices.'],
         })
 
+        f = self.G({'author': ['bar', 'baz']})
+        exc = translate_validation(f.errors)
+
+        # NOTE(stephenfin): Because we can't guarantee the order than filters
+        # are evaluated, we don't use 'assertDictEqual' here
+        self.assertEqual(set(exc.detail.keys()), {'author', })
+        self.assertRegex(str(exc.detail['author'][0]),
+                         '"ba[rz]" is not a valid value for a primary key.')
+
     def test_full_error_details(self):
         f = self.F(data={'id': 'foo', 'author': 'bar', 'name': 'baz'})
         exc = translate_validation(f.errors)