dataload-rs

dataload-rs is a utility that solves the GraphQL N+1 problem through batch loading.

Example

Add dataload-rs as a dependency:

toml dataload-rs = "0.1"

Define some batch function and corresponding context (a single context can be shared by multiple batch functions). Then create and use a loader with the BatchFunction.

```rust use asynctrait::asynctrait; use dataload_rs::{BatchFunction, Loader};

// Empty functor that implements the BatchFunction trait. For this example, it // trivially loads values from some HashMap. struct MyBatchFn;

[async_trait]

impl BatchFunction for MyBatchFn { type Context = HashMap;

async fn load(keys: &[i64], context: &Self::Context) -> Vec<(i64, String)> {
    keys.into_iter()
        .filter_map(|k| context.get(k).cloned().map(|v| (*k, v)))
        .collect()
}

}

[tokio::main]

async fn main() { let mut context = HashMap::new(); context.insert(2001, "a space odyssey".toowned()); context.insert(7, "samurai".toowned()); context.insert(12, "angry men".to_owned());

let loader = Loader::new(MyBatchFn {}, context);

assert_eq!(loader.load(7).await.as_deref(), Some("samurai"));
assert_eq!(loader.load(15).await, None);

assert_eq!(
    loader
        .load_many(vec![12, 2010, 2001])
        .await
        .iter()
        .map(Option::as_deref)
        .collect::<Vec<_>>(),
    vec![Some("angry men"), None, Some("a space odyssey")]
);

} ```