Suppress validation errors of descendent inlines of deleted forms

fixes #101

CHANGELOG.rst

@@ -10,8 +10,11 @@ Changelog
   ``autocomplete_lookup_fields`` (`#114`_)
 * Fixed: (grappelli) Collapsible tabular inlines with
   ``NestedTabularInline.classes`` now work. (`#90`_)
+* Fixed: Suppress validation errors of inlines nested beneath deleted inlines
+  (`#101`_)
 
 .. _#90: https://github.com/theatlantic/django-nested-admin/issues/90
+.. _#101: https://github.com/theatlantic/django-nested-admin/issues/101
 .. _#114: https://github.com/theatlantic/django-nested-admin/issues/114
 .. _#118: https://github.com/theatlantic/django-nested-admin/issues/118
 .. _#122: https://github.com/theatlantic/django-nested-admin/issues/122

nested_admin/__init__.py

@@ -95,6 +95,30 @@ def __getattr__(self, name):
     all_valid_patch_modules.append(admin_module)
 
 
+def descend_form(form):
+    for formset in getattr(form, 'nested_formsets', None) or []:
+        for child_formset, child_form in descend_formset(formset):
+            yield (child_formset, child_form)
+
+
+def descend_formset(formset):
+    for form in formset:
+        yield (formset, form)
+        for child_formset, child_form in descend_form(form):
+            yield child_formset, child_form
+
+
+def patch_delete_children_empty_permitted(formsets):
+    """Set empty_permitted=True for descendent forms of forms that are to be deleted"""
+    for top_level_formset in formsets:
+        for formset, form in descend_formset(top_level_formset):
+            formset._errors = None
+            form._errors = None
+            if formset.can_delete and formset._should_delete_form(form):
+                for _, child_form in descend_form(form):
+                    child_form.empty_permitted = True
+
+
 @monkeybiz.patch(all_valid_patch_modules)
 def all_valid(original_all_valid, formsets):
     """
@@ -104,8 +128,16 @@ def all_valid(original_all_valid, formsets):
     This causes a bug when one of the parent forms has empty_permitted == True,
     which happens if it is an "extra" form in the formset and its index
     is >= the formset's min_num.
+
+    Also hooks into the original validation to suppress validation errors thrown
+    by descendent inlines of deleted forms.
     """
     if not original_all_valid(formsets):
+        if len(formsets) and getattr(formsets[0], 'data', None):
+            has_delete = any(k for k in formsets[0].data if k.endswith('-DELETE'))
+            if has_delete:
+                patch_delete_children_empty_permitted(formsets)
+                return original_all_valid(formsets)
         return False
 
     for formset in formsets:

nested_admin/tests/nested_delete_validationerrors/admin.py

@@ -0,0 +1,20 @@
+from django.contrib import admin
+import nested_admin
+from .models import Parent, Child, GrandChild
+
+
+class GrandChildInline(nested_admin.NestedStackedInline):
+    model = GrandChild
+    extra = 0
+    min_num = 1
+
+
+class ChildInline(nested_admin.NestedStackedInline):
+    model = Child
+    inlines = [GrandChildInline]
+    extra = 0
+
+
+@admin.register(Parent)
+class ParentAdmin(nested_admin.NestedModelAdmin):
+    inlines = [ChildInline]

nested_admin/tests/nested_delete_validationerrors/models.py

@@ -0,0 +1,39 @@
+from __future__ import unicode_literals
+
+from django.db import models
+from django.db.models import ForeignKey, CASCADE
+from nested_admin.tests.compat import python_2_unicode_compatible
+
+
+@python_2_unicode_compatible
+class Parent(models.Model):
+    name = models.CharField(max_length=128)
+
+    def __str__(self):
+        return self.name
+
+
+@python_2_unicode_compatible
+class Child(models.Model):
+    name = models.CharField(max_length=128)
+    parent = ForeignKey(Parent, on_delete=CASCADE, related_name='children')
+    position = models.PositiveIntegerField()
+
+    class Meta:
+        ordering = ['position']
+
+    def __str__(self):
+        return self.name
+
+
+@python_2_unicode_compatible
+class GrandChild(models.Model):
+    name = models.CharField(max_length=128)
+    parent = ForeignKey(Child, on_delete=CASCADE, related_name='children')
+    position = models.PositiveIntegerField()
+
+    class Meta:
+        ordering = ['position']
+
+    def __str__(self):
+        return self.name

nested_admin/tests/nested_delete_validationerrors/tests.py

@@ -0,0 +1,37 @@
+import time
+from unittest import SkipTest
+
+from django.conf import settings
+
+from nested_admin.tests.base import BaseNestedAdminTestCase
+from .models import Parent, Child, GrandChild
+
+
+class TestDeleteNestedInlineMinNumRequirement(BaseNestedAdminTestCase):
+
+    root_model = Parent
+    nested_models = (Child, GrandChild)
+
+    def test_min_num_delete_bug(self):
+        """It should be possible to delete inlines, even if min_num requirement not met"""
+        rhea = Parent.objects.create(name='Rhea')
+        poseidon = Child.objects.create(name='Poseidon', parent=rhea, position=0)
+        zeus = Child.objects.create(name='Zeus', parent=rhea, position=1)
+        demeter = Child.objects.create(name='Demeter', parent=rhea, position=2)
+
+        GrandChild.objects.create(name='Apollo', parent=zeus, position=0)
+        GrandChild.objects.create(name='Persephone', parent=demeter, position=0)
+
+        self.load_admin(rhea)
+        self.delete_inline([0])
+        self.save_form()
+
+        validation_errors = self.selenium.execute_script(
+            "return $('ul.errorlist li').length")
+
+        self.assertEqual(
+            0, validation_errors, "Save should have completed without validation errors")
+
+        children = Child.objects.filter(parent=rhea)
+        self.assertNotEqual(3, len(children), "Child with empty grandchild was not deleted")
+        self.assertEqual(2, len(children))