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main.rs
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main.rs
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//! Example of application using <https://github.com/launchbadge/sqlx>
//!
//! Run with
//!
//! ```not_rust
//! cd examples && cargo run -p example-sqlx-postgres
//! ```
//!
//! Test with curl:
//!
//! ```not_rust
//! curl 127.0.0.1:3000
//! curl -X POST 127.0.0.1:3000
//! ```
use axum::{
async_trait,
extract::{FromRef, FromRequestParts, State},
http::{request::Parts, StatusCode},
routing::get,
Router,
};
use sqlx::postgres::{PgPool, PgPoolOptions};
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
use std::{net::SocketAddr, time::Duration};
#[tokio::main]
async fn main() {
tracing_subscriber::registry()
.with(
tracing_subscriber::EnvFilter::try_from_default_env()
.unwrap_or_else(|_| "example_tokio_postgres=debug".into()),
)
.with(tracing_subscriber::fmt::layer())
.init();
let db_connection_str = std::env::var("DATABASE_URL")
.unwrap_or_else(|_| "postgres://postgres:password@localhost".to_string());
// setup connection pool
let pool = PgPoolOptions::new()
.max_connections(5)
.connect_timeout(Duration::from_secs(3))
.connect(&db_connection_str)
.await
.expect("can connect to database");
// build our application with some routes
let app = Router::new()
.route(
"/",
get(using_connection_pool_extractor).post(using_connection_extractor),
)
.with_state(pool);
// 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();
}
// we can extract the connection pool with `State`
async fn using_connection_pool_extractor(
State(pool): State<PgPool>,
) -> Result<String, (StatusCode, String)> {
sqlx::query_scalar("select 'hello world from pg'")
.fetch_one(&pool)
.await
.map_err(internal_error)
}
// we can also write a custom extractor that grabs a connection from the pool
// which setup is appropriate depends on your application
struct DatabaseConnection(sqlx::pool::PoolConnection<sqlx::Postgres>);
#[async_trait]
impl<S> FromRequestParts<S> for DatabaseConnection
where
PgPool: FromRef<S>,
S: Send + Sync,
{
type Rejection = (StatusCode, String);
async fn from_request_parts(_parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
let pool = PgPool::from_ref(state);
let conn = pool.acquire().await.map_err(internal_error)?;
Ok(Self(conn))
}
}
async fn using_connection_extractor(
DatabaseConnection(conn): DatabaseConnection,
) -> Result<String, (StatusCode, String)> {
let mut conn = conn;
sqlx::query_scalar("select 'hello world from pg'")
.fetch_one(&mut conn)
.await
.map_err(internal_error)
}
/// 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())
}