[API]: Migration subsystem

[lev2p1]

Change Type

Enhancement

Current API

The AddIndex function in the ORM returns a string instead of a builder. I can't use it effectively, so I have to add indexes manually every time.

Proposed API

AddIndex must return a pointer to its own data type.

Rationale

This will greatly simplify the process of creating migrations.

Migration Path

Before:
        queries.push_back(
            builder.AddForeignKey("chat_id", "chats", "id")
            .AddForeignKey("sender_id", "users", "id")
            .AddIndex("idx_messages_chat_id", { "chat_id" })
        );

        queries.push_back(
            builder.AddIndex("idx_messages_sender_id", { "sender_id" })
        );

        queries.push_back(
            builder.AddIndex("idx_messages_created_at", { "created_at" })
        );

After:
        queries.push_back(
            builder.AddForeignKey("chat_id", "chats", "id")
            .AddForeignKey("sender_id", "users", "id")
            .AddIndex("idx_messages_chat_id", { "chat_id" })
            .AddIndex("idx_messages_sender_id", { "sender_id" })
            .AddIndex("idx_messages_created_at", { "created_at" })
        );

Backward Compatibility

Yes, this will break existing code.
The vector should store a string, not the builder. You will need to add an extra method to retrieve the string from the builder.

Usage Examples