add unique creation/deletion support to SchemaEditor.alter_field()

Author: timgraham

django_mongodb/features.py

@@ -72,12 +72,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "backends.tests.ThreadTests.test_pass_connection_between_threads",
         "backends.tests.ThreadTests.test_closing_non_shared_connections",
         "backends.tests.ThreadTests.test_default_connection_thread_local",
-        # AlterField
-        "schema.tests.SchemaTests.test_alter_field_fk_to_o2o",
-        "schema.tests.SchemaTests.test_alter_field_o2o_to_fk",
-        # AlterField (unique)
-        "schema.tests.SchemaTests.test_indexes",
-        "schema.tests.SchemaTests.test_unique",
     }
     # $bitAnd, #bitOr, and $bitXor are new in MongoDB 6.3.
     _django_test_expected_failures_bitwise = {

django_mongodb/schema.py

@@ -89,6 +89,11 @@ def _alter_field(
         strict=False,
     ):
         collection = self.get_collection(model._meta.db_table)
+        # Has unique been removed?
+        old_field_unique = self._field_should_have_unique(old_field)
+        new_field_unique = self._field_should_have_unique(new_field)
+        if old_field_unique and not new_field_unique:
+            self._remove_field_unique(model, old_field, strict)
         # Removed an index?
         old_field_indexed = self._field_should_be_indexed(model, old_field)
         new_field_indexed = self._field_should_be_indexed(model, new_field)
@@ -101,6 +106,10 @@ def _alter_field(
             if old_field_indexed and new_field_indexed:
                 self._remove_field_index(model, old_field)
                 self._add_field_index(model, new_field)
+            # Move unique to the new field, if needed.
+            if old_field_unique and new_field_unique:
+                self._remove_field_unique(model, old_field, strict)
+                self._add_field_unique(model, new_field)
         # Replace NULL with the field default if the field and was changed from
         # NULL to NOT NULL.
         if new_field.has_default() and old_field.null and not new_field.null:
@@ -110,6 +119,9 @@ def _alter_field(
         # Added an index?
         if not old_field_indexed and new_field_indexed:
             self._add_field_index(model, new_field)
+        # Added a unique?
+        if not old_field_unique and new_field_unique:
+            self._add_field_unique(model, new_field)
 
     def remove_field(self, model, field):
         # Remove implicit M2M tables.