async-graphql/src/docs/directive.md

Define a directive for query.

See also the Book.

Macro attributes

Attribute	description	Type	Optional
name	Object name	string	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
repeatable	It means that the directive can be used multiple times in the same location.	bool	Y
rename_args	Rename all the arguments according to the given case convention. The possible values are "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE".	string	Y
locations	Specify the location where the directive is available, multiples are allowed. The possible values is "field", ...	string	N

Directive attributes

Attribute	description	Type	Optional
name	Argument name	string	Y
desc	Argument description	string	Y
default	Use Default::default for default value	none	Y
default	Argument default value	literal	Y
default_with	Expression to generate default value	code string	Y
validator	Input value validator See also the Book	object	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
secret	Mark this field as a secret, it will not output the actual value in the log.	bool	Y

Examples

use async_graphql::*;

struct ConcatDirective {
    value: String,
}

#[async_trait::async_trait]
impl CustomDirective for ConcatDirective {
    async fn resolve_field(&self, _ctx: &Context<'_>, resolve: ResolveFut<'_>) -> ServerResult<Option<Value>> {
        resolve.await.map(|value| {
            value.map(|value| match value {
                Value::String(str) => Value::String(str + &self.value),
                _ => value,
            })
        })
    }
}

#[Directive(location = "field")]
fn concat(value: String) -> impl CustomDirective {
    ConcatDirective { value }
}

struct Query;

#[Object]
impl Query {
    async fn value(&self) -> &'static str {
        "abc"
    }
}

# tokio::runtime::Runtime::new().unwrap().block_on(async move {
let schema = Schema::build(Query, EmptyMutation, EmptySubscription)
    .directive(concat)
    .finish();
let res = schema.execute(r#"{ value @concat(value: "def") }"#).await.into_result().unwrap().data;
assert_eq!(res, value!({
    "value": "abcdef",
}));
# });