Enum async_graphql::types::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.into_result().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 is_value(&self) -> bool

Returns true if the MaybeUndefined is value.

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: Clone> Clone for MaybeUndefined<T>

fn clone(&self) -> MaybeUndefined<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for MaybeUndefined<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de, T> Deserialize<'de> for MaybeUndefined<T> where
    T: Deserialize<'de>, 

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
    __D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl<T: InputValueType> InputValueType for MaybeUndefined<T>

fn parse(value: Option<Value>) -> InputValueResult<Self>

Parse from Value. None represents undefined.

fn to_value(&self) -> Value

Convert to a Value for introspection.

impl<T> Serialize for MaybeUndefined<T> where
    T: Serialize, 

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error> where
    __S: Serializer, 

Serialize this value into the given Serde serializer.

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