Fixed #19545 -- Make sure media/is_multipart work with empty formsets

django/forms/formsets.py

@@ -333,7 +333,10 @@ def is_multipart(self):
         Returns True if the formset needs to be multipart, i.e. it
         has FileInput. Otherwise, False.
         """
-        return self.forms and self.forms[0].is_multipart()
+        if self.forms:
+            return self.forms[0].is_multipart()
+        else:
+            return self.empty_form.is_multipart()
 
     @property
     def media(self):
@@ -342,7 +345,7 @@ def media(self):
         if self.forms:
             return self.forms[0].media
         else:
-            return Media()
+            return self.empty_form.media
 
     def as_table(self):
         "Returns this formset rendered as HTML <tr>s -- excluding the <table></table>."

tests/regressiontests/forms/tests/formsets.py

@@ -1,8 +1,9 @@
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
-from django.forms import Form, CharField, IntegerField, ValidationError, DateField
-from django.forms.formsets import formset_factory, BaseFormSet
+from django.forms import (CharField, DateField, FileField, Form, IntegerField,
+    ValidationError)
+from django.forms.formsets import BaseFormSet, formset_factory
 from django.forms.util import ErrorList
 from django.test import TestCase
 
@@ -974,11 +975,23 @@ def test_empty_forms_are_unbound(self):
         self.assertHTMLEqual(empty_forms[0].as_p(), empty_forms[1].as_p())
 
 class TestEmptyFormSet(TestCase):
-    "Test that an empty formset still calls clean()"
     def test_empty_formset_is_valid(self):
+        """Test that an empty formset still calls clean()"""
         EmptyFsetWontValidateFormset = formset_factory(FavoriteDrinkForm, extra=0, formset=EmptyFsetWontValidate)
         formset = EmptyFsetWontValidateFormset(data={'form-INITIAL_FORMS':'0', 'form-TOTAL_FORMS':'0'},prefix="form")
         formset2 = EmptyFsetWontValidateFormset(data={'form-INITIAL_FORMS':'0', 'form-TOTAL_FORMS':'1', 'form-0-name':'bah' },prefix="form")
         self.assertFalse(formset.is_valid())
         self.assertFalse(formset2.is_valid())
 
+    def test_empty_formset_media(self):
+        """Make sure media is available on empty formset, refs #19545"""
+        class MediaForm(Form):
+            class Media:
+                js = ('some-file.js',)
+        self.assertIn('some-file.js', str(formset_factory(MediaForm, extra=0)().media))
+
+    def test_empty_formset_is_multipart(self):
+        """Make sure `is_multipart()` works with empty formset, refs #19545"""
+        class FileForm(Form):
+            file = FileField()
+        self.assertTrue(formset_factory(FileForm, extra=0)().is_multipart())