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Improve error catcher documentation in requests guide.

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Rolf Schmidt 2018-05-26 16:55:46 +02:00 committed by Sergio Benitez
parent 070529e1ac
commit 0842612607
1 changed files with 18 additions and 8 deletions
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site/guide/requests.md
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@ -742,24 +742,34 @@ errors, you'd write:
```rust ```rust
#[catch(404)] #[catch(404)]
fn not_found(req: &Request) -> String { ... } fn not_found(req: &Request) -> T { .. }
``` ```
As with routes, Rocket needs to know about a catcher before it is used to handle As with routes, the return type (here `T`) must implement `Responder`. A
errors. The process is similar to mounting: call the `catch` method with a list concrete implementation may look like:
of catchers via the `catchers!` macro. The invocation to add the **404** catcher
declared above looks like: ```rust
#[catch(404)]
fn not_found(req: &Request) -> String {
format!("Sorry, '{}' is not a valid path.", req.uri())
}
```
Also as with routes, Rocket needs to know about a catcher before it is used to
handle errors. The process is similar to mounting: call the `catch` method with
a list of catchers via the `catchers!` macro. The invocation to add the **404**
catcher declared above looks like:
```rust ```rust
rocket::ignite().catch(catchers![not_found]) rocket::ignite().catch(catchers![not_found])
``` ```
Unlike request handlers, error handlers can only take 0, 1, or 2 parameters of Unlike route request handlers, catchers can only take 0, 1, or 2 parameters of
types [`Request`](https://api.rocket.rs/rocket/struct.Request.html) and/or types [`Request`](https://api.rocket.rs/rocket/struct.Request.html) and/or
[`Error`](https://api.rocket.rs/rocket/enum.Error.html). At present, the `Error` [`Error`](https://api.rocket.rs/rocket/enum.Error.html). At present, the `Error`
type is not particularly useful, and so it is often omitted. The [error catcher type is not particularly useful, and so it is often omitted. The [error catcher
example](https://github.com/SergioBenitez/Rocket/tree/v0.4.0-dev/examples/errors) on example](https://github.com/SergioBenitez/Rocket/tree/v0.4.0-dev/examples/errors)
GitHub illustrates their use in full. on GitHub illustrates their use in full.
Rocket has a default catcher for all of the standard HTTP error codes including Rocket has a default catcher for all of the standard HTTP error codes including
**404**, **500**, and more. **404**, **500**, and more.