Struct trillium::Init [−][src]
pub struct Init<T>(_);
Expand description
Provides support for asynchronous initialization of a handler after the server is started.
use trillium::{Conn, State, Init}; #[derive(Debug, Clone)] struct MyDatabaseConnection(String); impl MyDatabaseConnection { async fn connect(uri: String) -> std::io::Result<Self> { Ok(Self(uri)) } async fn query(&mut self, query: &str) -> String { format!("you queried `{}` against {}", query, &self.0) } } let mut handler = ( Init::new(|_| async { let url = std::env::var("DATABASE_URL").unwrap(); let db = MyDatabaseConnection::connect(url).await.unwrap(); State::new(db) }), |mut conn: Conn| async move { let db = conn.state_mut::<MyDatabaseConnection>().unwrap(); let response = db.query("select * from users limit 1").await; conn.ok(response) } ); std::env::set_var("DATABASE_URL", "db://db"); use trillium_testing::prelude::*; init(&mut handler); assert_ok!( get("/").on(&handler), "you queried `select * from users limit 1` against db://db" );
Because () is the noop handler, this can also be used to perform one-time set up:
use trillium::{Init, Conn}; let mut handler = ( Init::new(|info| async move { log::info!("{}", info); }), |conn: Conn| async move { conn.ok("ok!") } ); use trillium_testing::prelude::*; init(&mut handler); assert_ok!(get("/").on(&handler), "ok!");
Implementations
Trait Implementations
Executes this handler, performing any modifications to the Conn that are desired. Read more
Performs one-time async set up on a mutable borrow of the Handler before the server starts accepting requests. This allows a Handler to be defined in synchronous code but perform async setup such as establishing a database connection or fetching some state from an external source. This is optional, and chances are high that you do not need this. Read more
Performs any final modifications to this conn after all handlers have been run. Although this is a slight deviation from the simple conn->conn->conn chain represented by most Handlers, it provides an easy way for libraries to effectively inject a second handler into a response chain. This is useful for loggers that need to record information both before and after other handlers have run, as well as database transaction handlers and similar library code. Read more
predicate function answering the question of whether this Handler
would like to take ownership of the negotiated Upgrade. If this
returns true, you must implement Handler::upgrade
. The first
handler that responds true to this will receive ownership of the
trillium::Upgrade
in a subsequent call to Handler::upgrade
Read more
This will only be called if the handler reponds true to
Handler::has_upgrade
and will only be called once for this
upgrade. There is no return value, and this function takes
exclusive ownership of the underlying transport once this is
called. You can downcast the transport to whatever the source
transport type is and perform any non-http protocol communication
that has been negotiated. You probably don’t want this unless
you’re implementing something like websockets. Please note that
for many transports such as TcpStreams, dropping the transport
(and therefore the Upgrade) will hang up / disconnect. Read more
Auto Trait Implementations
impl<T> !RefUnwindSafe for Init<T>
impl<T> !UnwindSafe for Init<T>