Implement param escaping for migraionts

django/db/backends/base/schema.py

@@ -223,7 +223,11 @@ def column_sql(self, model, field, include_default=False):
             default_value = self.effective_default(field)
             column_default = ' DEFAULT ' + self._column_default_sql(field)
             if default_value is not None:
-                if self.connection.features.requires_literal_defaults:
+                if hasattr(default_value, 'as_sql'):
+                    s, p = default_value.as_sql(self, self.connection)
+                    sql += column_default % s
+                    params += p
+                elif self.connection.features.requires_literal_defaults:
                     # Some databases can't take defaults as a parameter (oracle)
                     # If this is the case, the individual schema backend should
                     # implement prepare_default
@@ -480,7 +484,11 @@ def add_field(self, model, field):
             "column": self.quote_name(field.column),
             "definition": definition,
         }
-        self.execute(sql, params)
+        try:
+            self.execute(sql, params)
+        except:
+            print(sql, params)
+            raise
         # Drop the default if we need to
         # (Django usually does not use in-database defaults)
         if not self.skip_default(field) and self.effective_default(field) is not None:

tests/schema/models.py

@@ -9,16 +9,12 @@
 new_apps = Apps()
 
 
-class DBRetruningDateTimeField(models.DateTimeField):
-    db_returning = True
-
-
 class Author(models.Model):
     name = models.CharField(max_length=255)
     height = models.PositiveIntegerField(null=True, blank=True)
     weight = models.IntegerField(null=True, blank=True)
     uuid = models.UUIDField(null=True)
-    date_of_birth = DBRetruningDateTimeField(default=Now)
+    date_of_birth = models.DateTimeField(default=Now)
 
     class Meta:
         apps = new_apps

tests/schema/tests.py

@@ -2649,15 +2649,12 @@ def test_add_field_use_effective_default(self):
             self.assertEqual(item[0], None if connection.features.interprets_empty_strings_as_nulls else '')
 
     def test_add_field_default_db_returning(self):
-        class CreatedDateTimeField(DateTimeField):
-            db_returning = True
-
         # Create the table.
         with connection.schema_editor() as editor:
             editor.create_model(Author)
         # Add new field with database default.
         Author.objects.create(name='author 1')
-        new_field = CreatedDateTimeField(default=Now)
+        new_field = DateTimeField(default=Now)
         new_field.set_attributes_from_name('db_returning')
         with connection.schema_editor() as editor:
             editor.add_field(Author, new_field)
@@ -2668,21 +2665,16 @@ class CreatedDateTimeField(DateTimeField):
             self.assertIsNotNone(item[0])
 
     def test_alter_field_default_db_returning(self):
-        class PubDateTimeField(DateTimeField):
-            db_returning = True
-
         # Create the table.
         with connection.schema_editor() as editor:
             editor.create_model(BookWithoutAuthor)
         BookWithoutAuthor.objects.create(title='book 1', pub_date=datetime.datetime.now())
         # Alter to add field with database default.
         old_field = BookWithoutAuthor._meta.get_field('pub_date')
-        new_field = PubDateTimeField(default=Now)
+        new_field = DateTimeField(default=Now)
         new_field.set_attributes_from_name('pub_date')
         with connection.schema_editor() as editor:
             editor.alter_field(BookWithoutAuthor, old_field, new_field, strict=True)
-        book = BookWithoutAuthor.objects.create(title='book 2')
-        self.assertIsInstance(book.pub_date, datetime.datetime)
 
     def test_effective_default_db_default(self):
         """#31206 - effective_default() should be handle database defaults"""