GraphQL in Rust

use async_graphql::{Context, Object, Schema, SimpleObject};
 
#[derive(SimpleObject)]
struct User { id: i64, name: String }
 
struct Query;
 
#[Object]
impl Query {
    async fn user(&self, ctx: &Context<'_>, id: i64) -> async_graphql::Result<User> {
        Ok(User { id, name: "Ada".into() })
    }
}
 
type AppSchema = Schema<Query, async_graphql::EmptyMutation, async_graphql::EmptySubscription>;

use async_graphql::{Context, Object, Schema, SimpleObject};
use async_graphql_axum::{GraphQLRequest, GraphQLResponse};
use axum::{routing::post, Router};
 
#[derive(SimpleObject, Clone)]
struct User { id: i64, name: String }
 
#[derive(Clone)]
struct AppState { users: Vec<User> }
 
struct Query;
 
#[Object]
impl Query {
    async fn users(&self, ctx: &Context<'_>) -> Vec<User> {
        ctx.data_unchecked::<AppState>().users.clone()
    }
}
 
type AppSchema = Schema<Query, async_graphql::EmptyMutation, async_graphql::EmptySubscription>;
 
async fn graphql_handler(
    schema: axum::Extension<AppSchema>,
    req: GraphQLRequest,
) -> GraphQLResponse {
    schema.0.execute(req.into_inner()).await.into()
}
 
#[tokio::main]
async fn main() {
    let state = AppState { users: vec![User { id: 1, name: "Ada".into() }] };
    let schema = Schema::build(Query, async_graphql::EmptyMutation, async_graphql::EmptySubscription)
        .data(state)
        .finish();
    let app = Router::new()
        .route("/graphql", post(graphql_handler))
        .layer(axum::Extension(schema));
    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000").await.unwrap();
    axum::serve(listener, app).await.unwrap();
}

// DataLoader for batched DB fetch
// use async_graphql::dataloader::Loader