Cursor connections
Relay’s cursor connection specification is designed to provide a consistent method for query paging. For more details on the specification see the GraphQL Cursor Connections Specification。
Defining a cursor connection in async-graphql
is very simple, you just call the connection::query
function and query data in the closure.
#![allow(unused)] fn main() { extern crate async_graphql; use async_graphql::*; use async_graphql::types::connection::*; struct Query; #[Object] impl Query { async fn numbers(&self, after: Option<String>, before: Option<String>, first: Option<i32>, last: Option<i32>, ) -> Result<Connection<usize, i32, EmptyFields, EmptyFields>> { query(after, before, first, last, |after, before, first, last| async move { let mut start = after.map(|after| after + 1).unwrap_or(0); let mut end = before.unwrap_or(10000); if let Some(first) = first { end = (start + first).min(end); } if let Some(last) = last { start = if last > end - start { end } else { end - last }; } let mut connection = Connection::new(start > 0, end < 10000); connection.edges.extend( (start..end).into_iter().map(|n| Edge::with_additional_fields(n, n as i32, EmptyFields) )); Ok::<_, async_graphql::Error>(connection) }).await } } }