Attribute Macro async_graphql::Interface

#[Interface]

Define a GraphQL interface

Macro parameters

Attribute	description	Type	Optional
name	Object name	string	Y
desc	Object description	string	Y

Field parameters

Attribute	description	Type	Optional
name	Field name	string	N
type	Field type	string	N
desc	Field description	string	Y
context	Method with the context	string	Y
deprecation	Field deprecation reason	string	Y
args	Field arguments	[Arg]	Y

Field argument parameters

Attribute	description	Type	Optional
name	Argument name	string	N
type	Argument type	string	N
desc	Argument description	string	Y
default	Argument default value	string	Y

Define an interface

Define TypeA, TypeB, TypeC... Implement the MyInterface

#[Interface]
struct MyInterface(TypeA, TypeB, TypeC, ...);

Fields

The type, name, and parameters of the interface field must exactly match the type that implements the interface, The internal implementation is a forward of the function call. You can specify the field function name that implements the interface type through the 'method' property, or you can specify that the field function has a context parameter through the 'context' attribute.

use async_graphql::*;

struct TypeA {
    value: i32,
}

#[Object]
impl TypeA {
    /// Returns data borrowed from the context
    #[field]
    async fn value_a<'a>(&self, ctx: &'a Context<'_>) -> &'a str {
        ctx.data::<String>().as_str()
    }

    /// Returns data borrowed self
    #[field]
    async fn value_b(&self) -> &i32 {
        &self.value
    }

    /// With parameters
    #[field]
    async fn value_c(&self, a: i32, b: i32) -> i32 {
        a + b
    }
}

#[Interface(
    field(name = "value_a", type = "&'ctx str", context),
    field(name = "value_b", type = "&i32"),
    field(name = "value_c", type = "i32",
        arg(name = "a", type = "i32"),
        arg(name = "b", type = "i32")),
)]
struct MyInterface(TypeA);

struct QueryRoot;

#[Object]
impl QueryRoot {
    #[field]
    async fn type_a(&self) -> MyInterface {
        TypeA { value: 10 }.into()
    }
}

#[async_std::main]
async fn main() {
    let schema = Schema::new(QueryRoot, GQLEmptyMutation).data("hello".to_string());
    let res = schema.query(r#"
    {
        typeA {
            valueA
            valueB
            valueC(a: 3, b: 2)
        }
    }"#).execute().await.unwrap();
    assert_eq!(res, serde_json::json!({
        "typeA": {
            "valueA": "hello",
            "valueB": 10,
            "valueC": 5
        }
    }));
}