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//! Run with
//!
//! ```not_rust
//! cd examples && cargo run -p example-tokio-postgres
//! ```
use axum::{
async_trait,
extract::{FromRequest, RequestParts, State},
http::StatusCode,
routing::get,
Router,
};
use bb8::{Pool, PooledConnection};
use bb8_postgres::PostgresConnectionManager;
use std::net::SocketAddr;
use tokio_postgres::NoTls;
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
#[tokio::main]
async fn main() {
tracing_subscriber::registry()
.with(tracing_subscriber::EnvFilter::new(
std::env::var("RUST_LOG").unwrap_or_else(|_| "example_tokio_postgres=debug".into()),
))
.with(tracing_subscriber::fmt::layer())
.init();
// set up connection pool
let manager =
PostgresConnectionManager::new_from_stringlike("host=localhost user=postgres", NoTls)
.unwrap();
let pool = Pool::builder().build(manager).await.unwrap();
// build our application with some routes
let app = Router::with_state(pool).route(
"/",
get(using_connection_pool_extractor).post(using_connection_extractor),
);
// run it with hyper
let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
tracing::debug!("listening on {}", addr);
axum::Server::bind(&addr)
.serve(app.into_make_service())
.await
.unwrap();
}
type ConnectionPool = Pool<PostgresConnectionManager<NoTls>>;
async fn using_connection_pool_extractor(
State(pool): State<ConnectionPool>,
) -> Result<String, (StatusCode, String)> {
let conn = pool.get().await.map_err(internal_error)?;
let row = conn
.query_one("select 1 + 1", &[])
.await
.map_err(internal_error)?;
let two: i32 = row.try_get(0).map_err(internal_error)?;
Ok(two.to_string())
}
// we can also write a custom extractor that grabs a connection from the pool
// which setup is appropriate depends on your application
struct DatabaseConnection(PooledConnection<'static, PostgresConnectionManager<NoTls>>);
#[async_trait]
impl<B> FromRequest<ConnectionPool, B> for DatabaseConnection
where
B: Send,
{
type Rejection = (StatusCode, String);
async fn from_request(
req: &mut RequestParts<ConnectionPool, B>,
) -> Result<Self, Self::Rejection> {
let pool = req.state().clone();
let conn = pool.get_owned().await.map_err(internal_error)?;
Ok(Self(conn))
}
}
async fn using_connection_extractor(
DatabaseConnection(conn): DatabaseConnection,
) -> Result<String, (StatusCode, String)> {
let row = conn
.query_one("select 1 + 1", &[])
.await
.map_err(internal_error)?;
let two: i32 = row.try_get(0).map_err(internal_error)?;
Ok(two.to_string())
}
/// Utility function for mapping any error into a `500 Internal Server Error`
/// response.
fn internal_error<E>(err: E) -> (StatusCode, String)
where
E: std::error::Error,
{
(StatusCode::INTERNAL_SERVER_ERROR, err.to_string())
}
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