Fixed #29569 -- Fixed Cast() with AutoField and BigAutoField.

django/db/backends/mysql/operations.py

@@ -18,6 +18,8 @@ class DatabaseOperations(BaseDatabaseOperations):
         'PositiveIntegerField': (0, 4294967295),
     }
     cast_data_types = {
+        'AutoField': 'signed integer',
+        'BigAutoField': 'signed integer',
         'CharField': 'char(%(max_length)s)',
         'TextField': 'char',
         'IntegerField': 'signed integer',

django/db/backends/oracle/operations.py

@@ -52,6 +52,8 @@ END;
     # Oracle doesn't support string without precision; use the max string size.
     cast_char_field_without_max_length = 'NVARCHAR2(2000)'
     cast_data_types = {
+        'AutoField': 'NUMBER(11)',
+        'BigAutoField': 'NUMBER(19)',
         'TextField': cast_char_field_without_max_length,
     }
 

django/db/backends/postgresql/operations.py

@@ -8,6 +8,10 @@ from django.db.backends.base.operations import BaseDatabaseOperations
 class DatabaseOperations(BaseDatabaseOperations):
     cast_char_field_without_max_length = 'varchar'
     explain_prefix = 'EXPLAIN'
+    cast_data_types = {
+        'AutoField': 'integer',
+        'BigAutoField': 'bigint',
+    }
 
     def unification_cast_sql(self, output_field):
         internal_type = output_field.get_internal_type()

tests/db_functions/test_cast.py

@@ -39,6 +39,8 @@ class CastTests(TestCase):
 
     def test_cast_to_integer(self):
         for field_class in (
+            models.AutoField,
+            models.BigAutoField,
             models.IntegerField,
             models.BigIntegerField,
             models.SmallIntegerField,