Hands-On Microservices with Rust

Extracting the user's identifier

To modify a specific user, we need their identifier. REST specifies that you need to get the IDs from a path, because REST maps data entities to URLs.

We can extract a user's identifier using the tail of the path, which we already have. This is  why we use the starts_with method of the string, instead of checking for strong equality with USER_PATH to the path tails.

We previously declared the UserId type, which equals the u64 unsigned number. Add this code to the second branch of the previously-declared match expression with the (method, path) pattern to extract the user's identifier from the path:

let user_id = path.trim_left_matches(USER_PATH)        .parse::<UserId>()        .ok()        .map(|x| x as usize);

The str::trim_left_matches ...