How to access database connection from a Rocket's fairing? - postgresql

Question

I'm trying to use database connection from a Rocket's on_ignite fairing:
use sqlx::{ self, FromRow };
use rocket::fairing::{self, Fairing, Info, Kind};
use rocket::{Build, Rocket};
use crate::database::PostgresDb;
#[derive(FromRow)]
struct TableRow {
column_a: String,
column_b: String
}
#[rocket::async_trait]
impl Fairing for TableRow {
fn info(&self) -> Info {
Info {
name: "Cache table row",
kind: Kind::Ignite,
}
}
async fn on_ignite(&self, rocket: Rocket<Build>) -> fairing::Result {
let mut db = rocket
.state::<Connection<PostgresDb>>()
.expect("Unable to find db connection.");
let row = sqlx::query_as::<_, TableRow>("SELECT * FROM table WHERE id = 1;")
.fetch_one(&mut db)
.await
.unwrap();
fairing::Result::Ok(rocket.manage(row))
}
}
The problem is I get following rust error during .fetch_one(&mut db):
the trait bound `&mut rocket_db_pools::Connection<PostgresDb>: Executor<'_>` is not satisfied
the following other types implement trait `Executor<'c>`:
<&'c mut PgConnection as Executor<'c>>
<&'c mut PgListener as Executor<'c>>
<&'c mut PoolConnection<Postgres> as Executor<'c>>
<&'t mut Transaction<'c, Postgres> as Executor<'t>>
<&sqlx::Pool<DB> as Executor<'p>>rustcClick for full compiler diagnostic
cache_rbac_on_ignite.rs(56, 14): required by a bound introduced by this call
query_as.rs(132, 17): required by a bound in `QueryAs::<'q, DB, O, A>::fetch_all`
I tried solution suggested here: How to get the database Connection in rocket.rs Fairing. but it did not work out.
Here is the code:
use sqlx::{ self, FromRow, Database };
use rocket::fairing::{self, Fairing, Info, Kind};
use rocket::{Build, Rocket};
use crate::database::PostgresDb;
#[derive(FromRow)]
struct TableRow {
column_a: String,
column_b: String
}
#[rocket::async_trait]
impl Fairing for TableRow {
fn info(&self) -> Info {
Info {
name: "Cache table row",
kind: Kind::Ignite,
}
}
async fn on_ignite(&self, rocket: Rocket<Build>) -> fairing::Result {
let mut db = PostgresDb::get_one(rocket).await.unwrap();
let row = sqlx::query_as::<_, TableRow>("SELECT * FROM table WHERE id = 1;")
.fetch_one(&mut db)
.await
.unwrap();
fairing::Result::Ok(rocket.manage(row))
}
}
I get following rust error on line let mut db = PostgresDb::get_one(rocket).await.unwrap();:
no function or associated item named `get_one` found for struct `PostgresDb` in the current scope
function or associated item not found in `PostgresDb`rustcClick for full compiler diagnostic
mod.rs(8, 1): function or associated item `get_one` not found for this struct
What is the right way to use database connection inside of the fairing? Thank you!

Answer 1

Finally found an answer. Here is what worked for me:
use rocket::fairing::{self, Fairing, Info, Kind};
use rocket::{Build, Rocket};
use rocket_db_pools::{ sqlx::{ self, FromRow }, Database };
use crate::database::PostgresDb;
#[derive(FromRow)]
struct TableRow {
column_a: String,
column_b: String
}
#[rocket::async_trait]
impl Fairing for TableRow {
fn info(&self) -> Info {
Info {
name: "Cache table row",
kind: Kind::Ignite,
}
}
async fn on_ignite(&self, rocket: Rocket<Build>) -> fairing::Result {
let db = PostgresDb::fetch(&rocket).unwrap();
let mut conn = db.aquire().await.unwrap();
let row = sqlx::query_as::<_, TableRow>("SELECT * FROM table WHERE id = 1;")
.fetch_one(&mut conn)
.await
.unwrap();
fairing::Result::Ok(rocket.manage(row))
}
}