Trait async_graphql::Scalar

pub trait Scalar: Sized + Send {
    fn type_name() -> &'static str;
    fn parse(value: &Value) -> Option<Self>;
    fn to_json(&self) -> Result<Value>;

    fn description() -> Option<&'static str> { ... }
    fn is_valid(value: &Value) -> bool { ... }
}

Represents a GraphQL scalar

You can implement the trait to create a custom scalar.

Examples

use async_graphql::*;

struct MyInt(i32);

impl Scalar for MyInt {
    fn type_name() -> &'static str {
        "MyInt"
    }

    fn parse(value: &Value) -> Option<Self> {
        if let Value::Int(n) = value {
            Some(MyInt(n.as_i64().unwrap() as i32))
        } else {
            None
        }
    }

    fn to_json(&self) -> Result<serde_json::Value> {
        Ok(self.0.into())
    }
}

impl_scalar!(MyInt); // // Don't forget this one

Required methods

fn type_name() -> &'static str

The type name of a scalar.

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

Parse a scalar value, return Some(Self) if successful, otherwise return None.

fn to_json(&self) -> Result<Value>

Convert the scalar value to json value.

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Provided methods

fn description() -> Option<&'static str>

The description of a scalar.

fn is_valid(value: &Value) -> bool

Checks for a valid scalar value.

The default implementation is to try to parse it, and in some cases you can implement this on your own to improve performance.

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Implementations on Foreign Types

impl Scalar for bool

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for Tz

fn type_name() -> &'static str

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

fn to_json(&self) -> Result<Value>

impl Scalar for DateTime<Utc>

Implement the DateTime scalar

The input/output is a string in RFC3339 format.

fn type_name() -> &'static str

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

fn to_json(&self) -> Result<Value>

impl Scalar for f32

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for f64

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for i8

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for i16

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for i32

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for i64

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for u8

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for u16

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for u32

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for u64

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn to_json(&self) -> Result<Value>

impl Scalar for String

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn is_valid(value: &Value) -> bool

fn to_json(&self) -> Result<Value>

impl Scalar for Url

fn type_name() -> &'static str

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

fn to_json(&self) -> Result<Value>

impl Scalar for ObjectId

fn type_name() -> &'static str

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

fn to_json(&self) -> Result<Value>

impl Scalar for Uuid

fn type_name() -> &'static str

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

fn to_json(&self) -> Result<Value>

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Implementors

impl Scalar for Any

fn type_name() -> &'static str

fn description() -> Option<&'static str>

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

fn is_valid(_value: &Value) -> bool

fn to_json(&self) -> Result<Value>

impl Scalar for ID

fn type_name() -> &'static str

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

fn to_json(&self) -> Result<Value>

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