How to use “Type safe routing” of axum

The article will show you how to use the “Type safe routing” of axum.

axum is a web application framework of Rust.

You should be familiar a little with the axum for better understanding.

At the first step we create a normal Router.

A problem with normal routing, is that string the wrong path parameters results in a run-time error.

Specifically, "/api/users/:user_id" and ”/api/users/:user_i" both be success compile. At that moment, run-time error looks like…

⫸ curl localhost:8088/api/users/123
Invalid URL: missing field `user_id`

“Type safe routing” is solution to the problem.

Code looks like the below

In the case, if "/api/users/:user_id" is ”/api/users/:user_i" , then to be compile error like this.

error[E0026]: struct `PathParam` does not have a field named `user_i`
   --> src/main.rs:71:14
    |
 71 | #[typed_path("/api/users/:user_i")]
    |              ^^^^^^^^^^^^^^^^^^^^
    |              |
    |              struct `PathParam` does not have this field
    |              help: a field with a similar name exists: `user_id`

By the way, the correct response is this.

⫸ curl localhost:8088/api/users/123
{"user_id":"123"}

This is a little use case. Hopefully, the article will help you.