Rust Actix-Web v4 creating a response with custom header

Question

I am trying to create a response inside a handler with actix-web v4.

The header method has changed to append_header which now instead of a key value pair takes a header object.

The original documentation here gives the following example:

use actix_web::HttpResponse;

async fn index() -> HttpResponse {
    HttpResponse::Ok()
        .content_type("plain/text")
        .header("X-Hdr", "sample")
        .body("data")
}

I can create a header with append_header(ContentType::plaintext()) with a predefined mime name, but I haven't found any way to create a custom type.

I would have expected something like Header::from("'X-Hdr': 'sample'") to work but haven't found any way to create this header.

What would be the right way to create the 'X-Hdr':'sample' header in actix-web v4?

Ibraheem Ahmed · Accepted Answer · 2021-06-11 17:25:40Z

4

pub fn append_header<H>(&mut self, header: H) -> &mut Self where
    H: IntoHeaderPair,

The append_header method takes any type implementing IntoHeaderPair. If you look at the documentation for the trait you will see that it is implemented for:

(&'_ HeaderName, V)
(&'_ str, V)
(HeaderName, V)
(&'_ [u8], V)
(String, V)

V is any type implementing IntoHeaderValue, which includes String, &str, Vec, and integer types.

Therefore you can simply write .append_header(("X-Hdr", "sample"))

edited Jun 11, 2021 at 17:25

answered Jun 11, 2021 at 16:51

Ibraheem Ahmed

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4 Comments

Johannes Maria Frank Over a year ago

Thanks, if I wanted to implement this trait on my type, say a single &str "'X-Hdr':'sample'", how would I do this?

Ibraheem Ahmed Over a year ago

You would create a wrapper type and implement the try_into_header_pair method by splitting on a colon.

Ibraheem Ahmed Over a year ago

I don't see why you would want to do this though.

Johannes Maria Frank Over a year ago

While it does not really serve a purpose, I need to get a better understanding of how traits work. I had reviewed the source code and saw the implementation, but was unable to interpret it correctly. So TLDR; simple as an exercise ;-) Thanks again for the help.

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