Edward Rudd 3b7ed74d11 correct doc examples so they compile

- examples to fix still
  - error_extensions.md ResultExt example does not compile!
     - trait ErrorExtensions is not implemented for ParseIntError
  - dataloader
     - requires sqlx to work. So we either "stub" it OR we rewrite them simpler to use a  simple "faux" db library

2022-06-02 17:32:12 -04:00

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合并对象(MergedObject)

为同一类型实现多次Object

通常我们在Rust中可以为同一类型创建多个实现，但由于过程宏的限制，无法为同一个类型创建多个Object实现。例如，下面的代码将无法通过编译。

#[Object]
impl MyObject {
    async fn field1(&self) -> i32 {
        todo!()
    }
}

#[Object]
impl MyObject {
    async fn field2(&self) -> i32 {
        todo!()    
    }
}

用 #[derive(MergedObject)] 宏允许你合并多个独立的Object为一个.

提示: 每个#[Object]需要一个唯一的名称，即使在一个MergedObject内，所以确保每个对象有单独的名称。

# extern crate async_graphql;
# use async_graphql::*;
# #[derive(SimpleObject)]
# struct User { a: i32 }
# #[derive(SimpleObject)]
# struct Movie { a: i32 }
#[derive(Default)]
struct UserQuery;

#[Object]
impl UserQuery {
    async fn users(&self) -> Vec<User> {
        todo!()
    }
}

#[derive(Default)]
struct MovieQuery;

#[Object]
impl MovieQuery {
    async fn movies(&self) -> Vec<Movie> {
        todo!()
    }
}

#[derive(MergedObject, Default)]
struct Query(UserQuery, MovieQuery);

let schema = Schema::new(
    Query::default(),
    EmptyMutation,
    EmptySubscription
);

⚠️ 合并的对象无法在Interface中使用。

合并订阅

和MergedObject一样，你可以派生MergedSubscription来合并单独的＃[Subscription]块。

像合并对象一样，每个订阅块都需要一个唯一的名称。

# extern crate async_graphql;
# use async_graphql::*;
# use futures_util::stream::{Stream};
# #[derive(Default,SimpleObject)]
# struct Query { a: i32 }
#[derive(Default)]
struct Subscription1;

#[Subscription]
impl Subscription1 {
    async fn events1(&self) -> impl Stream<Item = i32> {
        futures_util::stream::iter(0..10)
    }
}

#[derive(Default)]
struct Subscription2;

#[Subscription]
impl Subscription2 {
    async fn events2(&self) -> impl Stream<Item = i32> {
        futures_util::stream::iter(10..20)
    }
}

#[derive(MergedSubscription, Default)]
struct Subscription(Subscription1, Subscription2);

let schema = Schema::new(
    Query::default(),
    EmptyMutation,
    Subscription::default()
);

2.2 KiB Raw Blame History Unescape Escape

合并对象(MergedObject)

为同一类型实现多次Object

合并订阅

2.2 KiB

Raw Blame History