Dev Blog

Summary ​

Conclusions ​

A REST web service exposes resources at URIs, and actions on them are defined by HTTP methods and status codes. ASP.NET Core Minimal API describes endpoints with Map… methods, groups them with MapGroup, and binds parameters from the route, the query string, the JSON body, and the dependency container. TypedResults make response codes explicit, the built-in .NET 10 validation checks DTOs, and ProblemDetails defines a single error format; OpenAPI and .http files are used to test the service. A repository behind an interface makes it possible to move from in-memory data to EF Core without changing the endpoints. Clients use an HttpClient from IHttpClientFactory and handle server unavailability and ProblemDetails bodies.

Self-check questions ​

  1. What parts do an HTTP request and response consist of? What are the Content-Type and Location headers for?
  2. Which HTTP methods are safe, and which are idempotent? Why does this matter when retrying a request?
  3. What status codes does a service return after a successful GET, POST, PUT, DELETE?
  4. What are a resource and a representation in REST? How do you build URIs for collections and items correctly?
  5. What does JsonSerializerOptions.Web enable? How do you write enumerations as names?
  6. How does Minimal API differ from controllers? What stages does Program.cs consist of?
  7. What is the middleware pipeline? Why does the order of app.Use… calls matter?
  8. How do you define a route parameter with a constraint? What is MapGroup for?
  9. From which sources does ASP.NET Core take the values of handler parameters?
  10. How does TypedResults differ from Results? What is the Results<Ok<T>, NotFound> type for?
  11. How do you enable the built-in validation in .NET 10? What does the client receive on an error?
  12. What is ProblemDetails? Which calls are needed so that all errors have this format?
  13. How do you get a service's OpenAPI document? How do you send a request from an .http file?
  14. Why is DbContext registered as Scoped? How do you implement pagination in the database?
  15. Why must you not create an HttpClient for every request? What is a typed client?