A data transfer object allows us to design an API endpoint with a specific data contract (input and output) instead of exposing the domain or data model. This separation between the presentation and the domain is a crucial element that leads to having multiple independent components instead of a bigger, more fragile one.We use DTOs to control the endpoints’ inputs and outputs, giving us more control over what the clients can do or receive.Using the data transfer object pattern helps us follow the SOLID principles in the following ways:
- S: A DTO adds clear boundaries between the domain or data model and the API contract. Moreover, having an input and an output DTO help further separate the responsibilities.
- O: N/A
- L: N/A
- I: A DTO is a small, specifically crafted data contract (abstraction) with a clear purpose in the API contract.
- D: Due to those smaller interfaces (ISP), DTOs allow changing the implementation details of the endpoint without affecting the clients because they depend only on the API contract (the abstraction).
You should now understand the added value of DTOs and what part in an API contract they play. Finally, you should have a strong base of Minimal APIs possibilities.
Summary
Throughout the chapter, we explored ASP.NET Core Minimal APIs and their integration with the DTO pattern. Minimal APIs simplify web application development by reducing boilerplate code. The DTO pattern helps us decouple the API contract from the application’s inner workings, allowing flexibility in crafting REST APIs. DTOs can also save bandwidth and flatten or change data structures. Endpoints exposing their domain or data entities directly can lead to issues, while DTO-enabled endpoints offer better control over data exchanges. We also discussed numerous Minimal APIs aspects, including input binding, outputting data, metadata, JSON serialization, endpoint filters, and endpoint organization. With this foundational knowledge, we can begin to design ASP.NET Core minimal APIs.
For more information about Minimal APIs and what they have to offer, you can visit the Minimal APIs quick reference page of the official documentation: https://adpg.link/S47i
In the next chapter, we revisit the same notions in an ASP.NET Core MVC context.