Fixed #20403 -- Ignore forms marked for deletion when validating max_…

…num.

django/forms/formsets.py

@@ -303,7 +303,8 @@ def full_clean(self):
             form = self.forms[i]
             self._errors.append(form.errors)
         try:
-            if (self.validate_max and self.total_form_count() > self.max_num) or \
+            if (self.validate_max and
+                self.total_form_count() - len(self.deleted_forms) > self.max_num) or \
                 self.management_form.cleaned_data[TOTAL_FORM_COUNT] > self.absolute_max:
                 raise ValidationError(ungettext(
                     "Please submit %d or fewer forms.",

docs/topics/forms/formsets.txt

@@ -283,7 +283,8 @@ Validating the number of forms in a formset
 
 If ``validate_max=True`` is passed to
 :func:`~django.forms.formsets.formset_factory`, validation will also check
-that the number of forms in the data set is less than or equal to ``max_num``.
+that the number of forms in the data set, minus those marked for
+deletion, is less than or equal to ``max_num``.
 
     >>> from django.forms.formsets import formset_factory
     >>> from myapp.forms import ArticleForm

tests/forms_tests/tests/test_formsets.py

@@ -986,6 +986,24 @@ def clean(self):
         self.assertEqual(list(formset.non_form_errors()),
             ['This is a non-form error'])
 
+    def test_validate_max_ignores_forms_marked_for_deletion(self):
+        class CheckForm(Form):
+           field = IntegerField()
+
+        data = {
+            'check-TOTAL_FORMS': '2',
+            'check-INITIAL_FORMS': '0',
+            'check-MAX_NUM_FORMS': '1',
+            'check-0-field': '200',
+            'check-0-DELETE': '',
+            'check-1-field': '50',
+            'check-1-DELETE': 'on',
+        }
+        CheckFormSet = formset_factory(CheckForm, max_num=1, validate_max=True,
+                                       can_delete=True)
+        formset = CheckFormSet(data, prefix='check')
+        self.assertTrue(formset.is_valid())
+
 
 data = {
     'choices-TOTAL_FORMS': '1', # the number of forms rendered