Derive Macro Union

#[derive(Union)]
{
    // Attributes available to this derive:
    #[graphql]
}

Define a GraphQL union

See also the Book.

Macro attributes

Attribute	description	Type	Optional
name	Object name	string	Y
name_type	If true, the object name will be specified from async_graphql::TypeName trait	bool	Y
visible	If false, it will not be displayed in introspection. See also the Book.	bool	Y
visible	Call the specified function. If the return value is false, it will not be displayed in introspection.	string	Y
inaccessible	Indicate that an union is not accessible from a supergraph when using Apollo Federation	bool	Y
tag	Arbitrary string metadata that will be propagated to the supergraph when using Apollo Federation. This attribute is repeatable	string	Y

Item attributes

Attribute	description	Type	Optional
flatten	Similar to serde (flatten)	boolean	Y

Define a union

Define TypeA, TypeB, … as MyUnion

use async_graphql::*;

#[derive(SimpleObject)]
struct TypeA {
    value_a: i32,
}

#[derive(SimpleObject)]
struct TypeB {
    value_b: i32
}

#[derive(Union)]
enum MyUnion {
    TypeA(TypeA),
    TypeB(TypeB),
}

struct Query;

#[Object]
impl Query {
    async fn all_data(&self) -> Vec<MyUnion> {
        vec![TypeA { value_a: 10 }.into(), TypeB { value_b: 20 }.into()]
    }
}

let schema = Schema::build(Query, EmptyMutation, EmptySubscription).data("hello".to_string()).finish();
let res = schema.execute(r#"
{
    allData {
        ... on TypeA {
            valueA
        }
        ... on TypeB {
            valueB
        }
    }
}"#).await.into_result().unwrap().data;
assert_eq!(res, value!({
    "allData": [
        { "valueA": 10 },
        { "valueB": 20 },
    ]
}));