Remove get_engine

This only affects add_index, so move engine picking code into that function.

privaterelay/migrations/0006_add_email_indexes.py

@@ -1,21 +1,20 @@
 # Generated by Django 3.2.20 on 2023-11-02 14:22
 
-from typing import Literal
-
 from django.apps.registry import Apps
 from django.db import migrations
 from django.db.backends.base.schema import BaseDatabaseSchemaEditor
 
 
-Engine = Literal["postgres", "sqlite"]
-
-
 def add_index(
-    schema_editor: BaseDatabaseSchemaEditor,
-    engine: Engine,
-    index_name: str,
-    table_name: str,
+    schema_editor: BaseDatabaseSchemaEditor, index_name: str, table_name: str
 ) -> None:
+    if schema_editor.connection.vendor.startswith("postgres"):
+        engine = "postgres"
+    elif schema_editor.connection.vendor.startswith("sqlite"):
+        engine = "sqlite"
+    else:
+        raise Exception(f'Unknown database vendor "{schema_editor.connection.vendor}"')
+
     if_not_exists = "IF NOT EXISTS" if engine == "postgres" else ""
     schema_editor.execute(
         f"CREATE INDEX {if_not_exists} {index_name} ON {table_name} (upper(email));"
@@ -26,24 +25,10 @@ def drop_index(schema_editor: BaseDatabaseSchemaEditor, index_name: str) -> None
     schema_editor.execute(f"DROP INDEX {index_name};")
 
 
-def get_engine(schema_editor) -> Engine:
-    if schema_editor.connection.vendor.startswith("postgres"):
-        return "postgres"
-    elif schema_editor.connection.vendor.startswith("sqlite"):
-        return "sqlite"
-    raise Exception(f'Unknown database vendor "{schema_editor.connection.vendor}"')
-
-
 def add_account_email_index(
     apps: Apps, schema_editor: BaseDatabaseSchemaEditor
 ) -> None:
-    engine = get_engine(schema_editor)
-    add_index(
-        schema_editor,
-        engine,
-        "account_emailaddress_email_upper",
-        "account_emailaddress",
-    )
+    add_index(schema_editor, "account_emailaddress_email_upper", "account_emailaddress")
 
 
 def drop_account_email_index(
@@ -53,8 +38,7 @@ def drop_account_email_index(
 
 
 def add_auth_email_index(apps: Apps, schema_editor: BaseDatabaseSchemaEditor) -> None:
-    engine = get_engine(schema_editor)
-    add_index(schema_editor, engine, "auth_user_email_upper", "auth_user")
+    add_index(schema_editor, "auth_user_email_upper", "auth_user")
 
 
 def drop_auth_email_index(apps: Apps, schema_editor: BaseDatabaseSchemaEditor) -> None: