SimpleObject

SimpleObject directly maps all the fields of a struct to GraphQL object. If you don't require automatic mapping of fields, see Object.

The example below defines an object MyObject which includes the fields a and b. c will be not mapped to GraphQL as it is labelled as #[graphql(skip)]


#![allow(unused)]
fn main() {
use async_graphql::*;

#[derive(SimpleObject)]
struct MyObject {
    /// Value a
    a: i32,

    /// Value b
    b: i32,

    #[graphql(skip)]
    c: i32,
}
}

User-defined resolvers

Sometimes most of the fields of a GraphQL object simply return the value of the structure member, but a few fields are calculated. In this case, the Object macro cannot be used unless you hand-write all the resolvers.

The ComplexObject macro works in conjuction with the SimpleObject macro. The SimpleObject derive macro defines the non-calculated fields, where as the ComplexObject macro let's you write user-defined resolvers for the calculated fields.

Resolvers added to ComplexObject adhere to the same rules as resolvers of Object.


#![allow(unused)]
fn main() {
#[derive(SimpleObject)]
#[graphql(complex)] // NOTE: If you want the `ComplexObject` macro to take effect, this `complex` attribute is required.
struct MyObj {
    a: i32,
    b: i32,
}

#[ComplexObject]
impl MyObj {
    async fn c(&self) -> i32 {
        self.a + self.b
    }
}
}

Generic SimpleObjects

If you want to reuse an SimpleObject for other types, you can define a generic SimpleObject and specify how its concrete types should be implemented.

In the following example, two SimpleObject types are created:


#![allow(unused)]
fn main() {
#[derive(SimpleObject)]
#[graphql(concrete(name = "SomeName", params(SomeType)))]
#[graphql(concrete(name = "SomeOtherName", params(SomeOtherType)))]
pub struct SomeGenericObject<T: OutputType> {
    field1: Option<T>,
    field2: String
}
}

Note: Each generic parameter must implement OutputType, as shown above.

The schema generated is:

type SomeName {
  field1: SomeType
  field2: String!
}

type SomeOtherName {
  field1: SomeOtherType
  field2: String!
}

In your resolver method or field of another object, use as a normal generic type:


#![allow(unused)]
fn main() {
#[derive(SimpleObject)]
pub struct YetAnotherObject {
    a: SomeGenericObject<SomeType>,
    b: SomeGenericObject<SomeOtherType>,
}
}

You can pass multiple generic types to params(), separated by a comma.