Field Guard
You can define a guard
for the fields of Object
, SimpleObject
, ComplexObject
and Subscription
, it will be executed before calling the resolver function, and an error will be returned if it fails.
#![allow(unused)] fn main() { extern crate async_graphql; use async_graphql::*; #[derive(Eq, PartialEq, Copy, Clone)] enum Role { Admin, Guest, } struct RoleGuard { role: Role, } impl RoleGuard { fn new(role: Role) -> Self { Self { role } } } #[async_trait::async_trait] impl Guard for RoleGuard { async fn check(&self, ctx: &Context<'_>) -> Result<()> { if ctx.data_opt::<Role>() == Some(&self.role) { Ok(()) } else { Err("Forbidden".into()) } } } }
Use it with the guard
attribute:
#![allow(unused)] fn main() { extern crate async_graphql; use async_graphql::*; #[derive(Eq, PartialEq, Copy, Clone)] enum Role { Admin, Guest, } struct RoleGuard { role: Role, } impl RoleGuard { fn new(role: Role) -> Self { Self { role } } } #[async_trait::async_trait] impl Guard for RoleGuard { async fn check(&self, ctx: &Context<'_>) -> Result<()> { todo!() } } #[derive(SimpleObject)] struct Query { /// Only allow Admin #[graphql(guard = "RoleGuard::new(Role::Admin)")] value1: i32, /// Allow Admin or Guest #[graphql(guard = "RoleGuard::new(Role::Admin).or(RoleGuard::new(Role::Guest))")] value2: i32, } }
Use parameter value
Sometimes guards need to use field parameters, you need to pass the parameter value when creating the guard like this:
#![allow(unused)] fn main() { extern crate async_graphql; use async_graphql::*; struct EqGuard { expect: i32, actual: i32, } impl EqGuard { fn new(expect: i32, actual: i32) -> Self { Self { expect, actual } } } #[async_trait::async_trait] impl Guard for EqGuard { async fn check(&self, _ctx: &Context<'_>) -> Result<()> { if self.expect != self.actual { Err("Forbidden".into()) } else { Ok(()) } } } struct Query; #[Object] impl Query { #[graphql(guard = "EqGuard::new(100, value)")] async fn get(&self, value: i32) -> i32 { value } } }