Why specify route parameter type in web api?

Question

I have a web api end point with a route parameter. It works with or without the route parameter type. I just would like to know why specify this in the following code?

[HttpGet]
[Route("{myId:int}")]
public HttpResponseMessage GetData([FromUri] int myId)
{
    //code here
}

This snippet [Route("{myId:int}")]. Why specify the int? There is already a int in this [FromUri] int myId. Wouldn't int for the route be redundant? Is there any reason for this?

Answer 1

Please see this example:

[Route("users/{id:int}"]
public User GetUserById(int id) { ... }

[Route("users/{name}"]
public User GetUserByName(string name) { ... }

Here, the first route will only be selected if the "id" segment of the URI is an integer. Otherwise, the second route will be chosen.

---

So in your case it's not required. But would be necessary if you need smarter route resolution. There are many different constraints that you can use. For example {x:minlength(10)} - string with min length of 10. {x:max(10)} - Matches an integer with a maximum value of 10. {x:regex(^\d{3}-\d{3}-\d{4}$)} - regex constraints etc.

You can find all the available constraints in the documentation.