[1.7.x] Fixed #23865 -- documented how to assign errors to a field in Model.clean()

Also added a unit test wit the simpler syntax which we have documented,
where the dictionary values are strings.

Backport of 5b26a014a81ba0d404d46e11d2b45c01d92b97e5 from master

2 files changed, 9 insertions, 0 deletions

diff --git a/tests/model_forms/models.py b/tests/model_forms/models.py
index 8936a17fc0..d54cccfe80 100644
--- a/tests/model_forms/models.py
+++ b/tests/model_forms/models.py
@@ -386,6 +386,8 @@ class CustomErrorMessage(models.Model):
     def clean(self):
         if self.name1 == 'FORBIDDEN_VALUE':
             raise ValidationError({'name1': [ValidationError('Model.clean() error messages.')]})
+        elif self.name1 == 'FORBIDDEN_VALUE2':
+            raise ValidationError({'name1': 'Model.clean() error messages (simpler syntax).'})
         elif self.name1 == 'GLOBAL_ERROR':
             raise ValidationError("Global error message.")
 
diff --git a/tests/model_forms/tests.py b/tests/model_forms/tests.py
index 489137bd35..78c3bca416 100644
--- a/tests/model_forms/tests.py
+++ b/tests/model_forms/tests.py
@@ -2207,6 +2207,13 @@ class ModelFormCustomErrorTests(TestCase):
             str(form.errors['name1']),
             '<ul class="errorlist"><li>Model.clean() error messages.</li></ul>'
         )
+        data = {'name1': 'FORBIDDEN_VALUE2', 'name2': 'ABC'}
+        form = CustomErrorMessageForm(data)
+        self.assertFalse(form.is_valid())
+        self.assertHTMLEqual(
+            str(form.errors['name1']),
+            '<ul class="errorlist"><li>Model.clean() error messages (simpler syntax).</li></ul>'
+        )
         data = {'name1': 'GLOBAL_ERROR', 'name2': 'ABC'}
         form = CustomErrorMessageForm(data)
         self.assertFalse(form.is_valid())