From ff111ea5e39cf774b3cd4237790d2bffd2826fb0 Mon Sep 17 00:00:00 2001
From: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Date: Thu, 1 Aug 2019 11:20:56 +0200
Subject: [PATCH] Refs #30664 -- Fixed migrations crash when altering
 AutoField/BigAutoField with quoted db_column on PostgreSQL.

---
 django/db/backends/postgresql/schema.py |  2 +-
 tests/schema/tests.py                   | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/django/db/backends/postgresql/schema.py b/django/db/backends/postgresql/schema.py
index 9e07bccf8b..b7f52ccf25 100644
--- a/django/db/backends/postgresql/schema.py
+++ b/django/db/backends/postgresql/schema.py
@@ -70,7 +70,7 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
         # Make ALTER TYPE with SERIAL make sense.
         table = strip_quotes(model._meta.db_table)
         if new_type.lower() in ("serial", "bigserial"):
-            column = new_field.column
+            column = strip_quotes(new_field.column)
             sequence_name = "%s_%s_seq" % (table, column)
             col_type = "integer" if new_type.lower() == "serial" else "bigint"
             return (
diff --git a/tests/schema/tests.py b/tests/schema/tests.py
index 287ef200da..a765528d50 100644
--- a/tests/schema/tests.py
+++ b/tests/schema/tests.py
@@ -636,6 +636,26 @@ class SchemaTests(TransactionTestCase):
         with connection.schema_editor() as editor:
             editor.alter_field(Author, old_field, new_field, strict=True)
 
+    @isolate_apps('schema')
+    def test_alter_auto_field_quoted_db_column(self):
+        class Foo(Model):
+            id = AutoField(primary_key=True, db_column='"quoted_id"')
+
+            class Meta:
+                app_label = 'schema'
+
+        with connection.schema_editor() as editor:
+            editor.create_model(Foo)
+        self.isolated_local_models = [Foo]
+        old_field = Foo._meta.get_field('id')
+        new_field = BigAutoField(primary_key=True)
+        new_field.model = Foo
+        new_field.db_column = '"quoted_id"'
+        new_field.set_attributes_from_name('id')
+        with connection.schema_editor() as editor:
+            editor.alter_field(Foo, old_field, new_field, strict=True)
+        Foo.objects.create()
+
     def test_alter_not_unique_field_to_primary_key(self):
         # Create the table.
         with connection.schema_editor() as editor: