DTOs: What, Why, and How?
DTO stands for Data Transfer Object, and it’s a pattern used to move data between different parts of your app, or between systems. The main idea is to have a simple object whose only job is to carry data,no business logic, no behavior, just data.
Why is this useful? Imagine you have a complex internal model for a user, with lots of fields and relationships. When you expose user data through an API, you probably don’t want to send everything,just the fields that are relevant for the client. A DTO lets you shape the data exactly how you need it, without exposing your internal structures.
DTOs also make it easier to change your internal code without breaking external integrations. If you need to rename a field or add new properties to your model, you can keep the DTO the same and just update the mapping. This decouples your internal logic from your external interfaces.
In practice, you’ll often create DTOs for API requests a nd responses. For example, you might have a UserDTO that only includes id, name, and email, even if your internal User model has many more fields. You map your model to the DTO before sending data out, and map incoming data to your model when receiving it.
DTOs are especially useful in layered architectures and microservices, where you want to keep boundaries clear and avoid leaking implementation details. Just remember: keep DTOs simple, and don’t put business logic in them,they’re just for moving data around.
In short, DTOs help you control and organize how data moves around your app and between systems, making your code safer and easier to maintain.