refs #134: fix test_alter_size_for_unique with redshift. Redshift can…

… not accept ADD COLUMN with UNIQUE, so we neet adding column without UNIQUE then add UNIQUE CONSTRAINT.

django_redshift_backend/base.py

@@ -307,6 +307,13 @@ def add_field(self, model, field):
             "column": self.quote_name(field.column),
             "definition": definition,
         }
+
+        # ## Redshift
+        if field.unique:
+            # temporarily remove UNIQUE constraint from sql
+            # because Redshift can't add column with UNIQUE constraint.
+            sql = sql.rstrip(" UNIQUE")
+
         # ## Redshift
         if not field.null and self.effective_default(field) is None:
             # Redshift Can't add NOT NULL column without DEFAULT.
@@ -321,6 +328,10 @@ def add_field(self, model, field):
         # ## original BasePGDatabaseSchemaEditor.add_field has CREATE INDEX.
         # ## Redshift doesn't support INDEX.
 
+        # Add UNIQUE constraints later
+        if field.unique:
+            self.deferred_sql.append(self._create_unique_sql(model, [field]))
+
         # Add any FK constraints later
         if (
             field.remote_field

tests/test_migrations.py

@@ -66,6 +66,32 @@ def test_alter_size(self):
             '''ALTER TABLE "test_pony" ALTER COLUMN "name" TYPE varchar(10);''',
         ], sqls)
 
+    @postgres_fixture()
+    def test_add_unique_column(self):
+        new_state = self.set_up_test_model('test')
+        operations = [
+            migrations.AddField(
+                model_name='Pony',
+                name='name_with_default',
+                field=models.CharField(max_length=10, default='', unique=True),
+            ),
+            migrations.AddField(
+                model_name='Pony',
+                name='name_with_nullable',
+                field=models.CharField(max_length=10, null=True, unique=True),
+            ),
+        ]
+
+        with self.collect_sql() as sqls:
+            self.apply_operations('test', new_state, operations)
+
+        self.assertEqual([
+            '''ALTER TABLE "test_pony" ADD COLUMN "name_with_default" varchar(10) DEFAULT '' NOT NULL;''',
+            '''ALTER TABLE "test_pony" ADD COLUMN "name_with_nullable" varchar(10) NULL;''',
+            '''ALTER TABLE "test_pony" ADD CONSTRAINT "test_pony_name_with_default_b3620670_uniq" UNIQUE ("name_with_default");''',
+            '''ALTER TABLE "test_pony" ADD CONSTRAINT "test_pony_name_with_nullable_d1043f78_uniq" UNIQUE ("name_with_nullable");''',
+        ], sqls)
+
     @postgres_fixture()
     def test_alter_size_for_unique(self):
         new_state = self.set_up_test_model('test')
@@ -86,10 +112,11 @@ def test_alter_size_for_unique(self):
             self.apply_operations('test', new_state, operations)
 
         self.assertEqual([
-            '''ALTER TABLE "test_pony" ADD COLUMN "name" varchar(10) DEFAULT '' NOT NULL UNIQUE;''',
-            '''ALTER TABLE "test_pony" DROP CONSTRAINT "test_pony_name_key";''',
+            '''ALTER TABLE "test_pony" ADD COLUMN "name" varchar(10) DEFAULT '' NOT NULL;''',
+            # ADD UNIQUE "name"
+            # DROP UNIQUE "name"
             '''ALTER TABLE "test_pony" ALTER COLUMN "name" TYPE varchar(20);''',
-            '''ALTER TABLE "test_pony" ADD CONSTRAINT "test_pony_name_key" UNIQUE ("name");'''
+            '''ALTER TABLE "test_pony" ADD CONSTRAINT "test_pony_name_2c070d2a_uniq" UNIQUE ("name");'''
         ], sqls)
 
     @postgres_fixture()