Enum async_graphql::MaybeUndefined

pub enum MaybeUndefined<T> {
    Undefined,
    Null,
    Value(T),
}

Similar to Option, but it has three states, undefined, null and x.

Reference: https://spec.graphql.org/June2018/#sec-Null-Value

Examples

use async_graphql::*;

struct Query;

#[Object]
impl Query {
    async fn value1(&self, input: MaybeUndefined<i32>) -> i32 {
        if input.is_null() {
            1
        } else if input.is_undefined() {
            2
        } else {
            input.take().unwrap()
        }
    }
}

#[async_std::main]
async fn main() {
    let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
    let query = r#"
        {
            v1:value1(input: 99)
            v2:value1(input: null)
            v3:value1()
        }"#;
    assert_eq!(
        schema.execute(&query).await.unwrap().data,
        serde_json::json!({
            "v1": 99,
            "v2": 1,
            "v3": 2,
        })
    );
}

Variants

Undefined

Null

Value(T)

Implementations

impl<T> MaybeUndefined<T>

pub fn is_undefined(&self) -> bool

Returns true if the MaybeUndefined is undefined.

pub fn is_null(&self) -> bool

Returns true if the MaybeUndefined is null.

pub fn value(&self) -> Option<&T>

Borrow the value, returns None if the value is undefined or null, otherwise returns Some(T).

pub fn take(self) -> Option<T>

Convert MaybeUndefined to Option.

Trait Implementations

impl<T: Type> Type for MaybeUndefined<T>

fn type_name() -> Cow<'static, str>

Type the name.

fn qualified_type_name() -> String

Qualified typename.

fn create_type_info(registry: &mut Registry) -> String

Create type information in the registry and return qualified typename.

fn introspection_type_name(&self) -> Cow<'static, str>

Introspection type name