What does the value of Outcome::Forward do?

[najtin]

Hi, the only thing in the documentation i could find was:

Contains the value to forward on.

What does that mean? Is the data somehow supplied to the next route?

See https://api.rocket.rs/master/rocket/outcome/enum.Outcome.html and
https://api.rocket.rs/master/rocket/outcome/index.html

[somehowchris]

Well it's really good described alongside the example of https://api.rocket.rs/master/rocket/outcome/index.html#forward

[somehowchris]

Please read the docs

[somehowchris]

Ultimately, if there are no non-forwarding routes, forwarded requests are handled by the 404 catcher. Similar to Failures, users can catch Forwards by requesting a type of Option<S>. If an Outcome is a Forward, the Option will be None.

[najtin]

I read this page up and down multiple times before asking the question here, and i don't find the answer there. Yes, Forward can be catched, but the question is what happens to the value of type F supplied during the constructions of Forward? An Outcome has type Outcome<S, E, F> where S is the type of the data supplied to Outcome::Success and F is the type of the data supplied to Outcome::Forward.
Outcome::Forward(something of type F) What is something of type F used for? Can the next route somehow access it? If not, what is it for? Is it the request that should be inside the forwardOutcome::Forward(request)?
Maybe i will take a look into the source code tomorrow and try to figure it out.

[somehowchris]

You might wanna load a guard within a guard and then check on it's outcome but I'm not aware of any feature letting you have a look at the outcome of a previous route, you may wanna check out local_cache If you need to save something within the scope of the request

[the10thWiz]

It depends on the use case. In FromData, the forward variant is used to pass the data on to the next handler.

In FromRequest, the forward variant has no data (it's literally ()).

In general, my understand is that F is only used when needed, otherwise it doesn't actually contain any information.