1 unstable release
0.1.0 | Mar 31, 2021 |
---|
#379 in Caching
19KB
292 lines
dataload-rs
dataload-rs is a utility that solves the GraphQL N+1 problem through batch loading.
Example
Add dataload-rs as a dependency:
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.
use async_trait::async_trait;
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<i64, String> for MyBatchFn {
type Context = HashMap<i64, String>;
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".to_owned());
context.insert(7, "samurai".to_owned());
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")]
);
}
Dependencies
~3–5MB
~83K SLoC