Struct rocket::State
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pub struct State<'r, T: Send + Sync + 'static>(_);
Request guard to retrieve managed state.
This type can be used as a request guard to retrieve the state Rocket is
managing for some type T
. This allows for the sharing of state across any
number of handlers. A value for the given type must previously have been
registered to be managed by Rocket via the
manage method. The type being
managed must be thread safe and sendable across thread boundaries. In other
words, it must implement Send + Sync + 'static
.
Example
Imagine you have some configuration struct of the type MyConfig
that you'd
like to initialize at start-up and later access it in several handlers. The
following example does just this:
use rocket::State; // In a real application, this would likely be more complex. struct MyConfig(String); #[get("/")] fn index(state: State<MyConfig>) -> String { format!("The config value is: {}", state.0) } #[get("/raw")] fn raw_config_value<'r>(state: State<'r, MyConfig>) -> &'r str { // use `inner()` to get a lifetime longer than `deref` gives us state.inner().0.as_str() } fn main() { let config = MyConfig("user input".to_string()); rocket::ignite() .mount("/", routes![index, raw_config_value]) .manage(config) .launch() }
Methods
impl<'r, T: Send + Sync + 'static> State<'r, T>
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fn inner(&self) -> &'r T
Retrieve a borrow to the underyling value.
Using this method is typically unnecessary as State
implements Deref
with a Target
of T
. This means Rocket will automatically coerce a
State<T>
to an &T
when the types call for it.
Trait Implementations
impl<'r, T: Debug + Send + Sync + 'static> Debug for State<'r, T>
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impl<'r, T: PartialEq + Send + Sync + 'static> PartialEq for State<'r, T>
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fn eq(&self, __arg_0: &State<'r, T>) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, __arg_0: &State<'r, T>) -> bool
This method tests for !=
.
impl<'r, T: Eq + Send + Sync + 'static> Eq for State<'r, T>
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impl<'a, 'r, T: Send + Sync + 'static> FromRequest<'a, 'r> for State<'r, T>
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type Error = ()
The associated error to be returned if derivation fails.
fn from_request(req: &'a Request<'r>) -> Outcome<State<'r, T>, ()>
Derives an instance of Self
from the incoming request metadata. Read more