From 06a11ef6ecf324db0a1530b8cca727883698f442 Mon Sep 17 00:00:00 2001
From: Demur Nodia <demur.nodia@gmail.com>
Date: Sun, 27 May 2018 13:06:37 +0300
Subject: [PATCH] Fixed #26819 -- Fixed BaseModelFormSet.validate_unique()
 "unhashable type: list" crash.

---
 django/forms/models.py        |  8 ++++++--
 tests/model_formsets/tests.py | 27 +++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/django/forms/models.py b/django/forms/models.py
index 7f5e2544dd..aa35ef5f92 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -696,8 +696,12 @@ class BaseModelFormSet(BaseFormSet):
                     for field in unique_check if field in form.cleaned_data
                 )
                 # Reduce Model instances to their primary key values
-                row_data = tuple(d._get_pk_val() if hasattr(d, '_get_pk_val') else d
-                                 for d in row_data)
+                row_data = tuple(
+                    d._get_pk_val() if hasattr(d, '_get_pk_val')
+                    # Prevent "unhashable type: list" errors later on.
+                    else tuple(d) if isinstance(d, list)
+                    else d for d in row_data
+                )
                 if row_data and None not in row_data:
                     # if we've already seen it then we have a uniqueness failure
                     if row_data in seen_data:
diff --git a/tests/model_formsets/tests.py b/tests/model_formsets/tests.py
index 4d00a589ce..d823a78ae8 100644
--- a/tests/model_formsets/tests.py
+++ b/tests/model_formsets/tests.py
@@ -1459,6 +1459,33 @@ class ModelFormsetTest(TestCase):
         self.assertEqual(player1.team, team)
         self.assertEqual(player1.name, 'Bobby')
 
+    def test_inlineformset_with_arrayfield(self):
+        class SimpleArrayField(forms.CharField):
+            """A proxy for django.contrib.postgres.forms.SimpleArrayField."""
+            def to_python(self, value):
+                value = super().to_python(value)
+                return value.split(',') if value else []
+
+        class BookForm(forms.ModelForm):
+            title = SimpleArrayField()
+
+            class Meta:
+                model = Book
+                fields = ('title',)
+
+        BookFormSet = inlineformset_factory(Author, Book, form=BookForm)
+        data = {
+            'book_set-TOTAL_FORMS': '3',
+            'book_set-INITIAL_FORMS': '0',
+            'book_set-MAX_NUM_FORMS': '',
+            'book_set-0-title': 'test1,test2',
+            'book_set-1-title': 'test1,test2',
+            'book_set-2-title': 'test3,test4',
+        }
+        author = Author.objects.create(name='test')
+        formset = BookFormSet(data, instance=author)
+        self.assertEqual(formset.errors, [{}, {'__all__': ['Please correct the duplicate values below.']}, {}])
+
     def test_model_formset_with_custom_pk(self):
         # a formset for a Model that has a custom primary key that still needs to be
         # added to the formset automatically