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Using newtype for context

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jsus 2021-09-24 14:35:46 +03:00 committed by Christian Legnitto
parent 6ba8ead1fd
commit 13fc0dadeb
1 changed files with 10 additions and 4 deletions
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14
docs/book/content/types/objects/using_contexts.md
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@ -101,23 +101,29 @@ For example, when using async runtime with [work stealing][2] (like `tokio`), wh
# use juniper::graphql_object;
use tokio::sync::RwLock;
impl juniper::Context for Database {}
struct Database {
requested_count: HashMap<i32, i32>,
}
// Since we cannot directly implement juniper::Context
// for RwLock we use the newtype idiom
struct DatabaseContext(RwLock<Database>)
impl juniper::Context for DatabaseContext {}
struct User {
id: i32,
name: String
}
#[graphql_object(context=RwLock<Database>)]
#[graphql_object(context=DatabaseContext)]
impl User {
async fn times_requested<'db>(&self, context: &'db RwLock<Database>) -> i32 {
async fn times_requested<'db>(&self, context: &'db DatabaseContext) -> i32 {
// Acquire a mutable reference and await if async RwLock is used,
// which is necessary if context consists async operations like
// querying remote databases.
// Obtain base type
let DatabaseContext(context) = context;
// If context is immutable use .read() on RwLock.
let mut context = context.write().await;
// Preform a mutable operation.