Fixed #20199 -- Allow ModelForm fields to override error_messages from model fields

tests/model_forms/tests.py

@@ -22,7 +22,7 @@ from .models import (Article, ArticleStatus, BetterWriter, BigInt, Book,
     DerivedPost, ExplicitPK, FlexibleDatePost, ImprovedArticle,
     ImprovedArticleWithParentLink, Inventory, Post, Price,
     Product, TextFile, Writer, WriterProfile, Colour, ColourfulItem,
-    ArticleStatusNote, DateTimePost, test_images)
+    ArticleStatusNote, DateTimePost, CustomErrorMessage, test_images)
 
 if test_images:
     from .models import ImageFile, OptionalImageFile
@@ -252,6 +252,12 @@ class StatusNoteCBM2mForm(forms.ModelForm):
         fields = '__all__'
         widgets = {'status': forms.CheckboxSelectMultiple}
 
+class CustomErrorMessageForm(forms.ModelForm):
+    name1 = forms.CharField(error_messages={'invalid': 'Form custom error message.'})
+
+    class Meta:
+        model = CustomErrorMessage
+
 
 class ModelFormBaseTest(TestCase):
     def test_base_form(self):
@@ -1762,6 +1768,18 @@ class OldFormForXTests(TestCase):
         </select> <span class="helptext"> Hold down "Control", or "Command" on a Mac, to select more than one.</span></p>"""
             % {'blue_pk': colour.pk})
 
+    def test_custom_error_messages(self) :
+        data = {'name1': '@#$!!**@#$', 'name2': '@#$!!**@#$'}
+        errors = CustomErrorMessageForm(data).errors
+        self.assertHTMLEqual(
+            str(errors['name1']),
+            '<ul class="errorlist"><li>Form custom error message.</li></ul>'
+        )
+        self.assertHTMLEqual(
+            str(errors['name2']),
+            '<ul class="errorlist"><li>Model custom error message.</li></ul>'
+        )
+
 
 class M2mHelpTextTest(TestCase):
     """Tests for ticket #9321."""