Using Hyper headers in Rocket 0.5

[barlindhaug]

I've started migrating to rocket 0.5 and ran into an issue when using hyper headers.

.header(Header::new(
    hyper::header::CACHE_CONTROL.as_str(),
    "max-age=2678400",
))

Looking at rocket::http::struct::Header::new, I see

Constructs a new header. This method should be used rarely and only for non-standard headers. Instead, prefer to use the Into<Header> implementations of many types, including ContentType and all of the headers in http::hyper::header.

So my question is how I should use the Into<Header> implementation.

Previously on rocket 0.4 the code was

.header(CacheControl(vec![CacheDirective::MaxAge(2678400u32)]))

[jebrosen]

So my question is how I should use the Into<Header> implementation.

Yes, a lot of these have been lost between 0.4 and 0.5-rc. That's now a mismatch in documentation, so this text will need to be updated or removed.

Rocket 0.4 was based on hyper 0.10, which included those typed headers, and rocket re-exported them. The typed headers were removed some time between then and hyper 0.13, and we haven't yet found a suitable replacement (see issue #1067). The most recent attempt was in #1535 using the hyperx crate, but the performance costs were deemed too high to go with that approach. Unfortunately, the next-best and more performant option, headers, has some usability issues; in particular several header types in the library are not actually constructible.