Trait ScalarType

pub trait ScalarType: Sized + Send {
    // Required methods
    fn parse(value: Value) -> InputValueResult<Self>;
    fn to_value(&self) -> Value;

    // Provided method
    fn is_valid(_value: &Value) -> bool { ... }
}

A GraphQL scalar.

You can implement the trait to create a custom scalar.

Examples

use async_graphql::*;

struct MyInt(i32);

#[Scalar]
impl ScalarType for MyInt {
    fn parse(value: Value) -> InputValueResult<Self> {
        if let Value::Number(n) = &value {
            if let Some(n) = n.as_i64() {
                return Ok(MyInt(n as i32));
            }
        }
        Err(InputValueError::expected_type(value))
    }

    fn to_value(&self) -> Value {
        Value::Number(self.0.into())
    }
}

Required Methods

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

Parse a scalar value.

fn to_value(&self) -> Value

Convert the scalar to Value.

Provided Methods

fn is_valid(_value: &Value) -> bool

Checks for a valid scalar value.

Implementing this function can find incorrect input values during the verification phase, which can improve performance.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl ScalarType for bool

The Boolean scalar type represents true or false.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for char

The Char scalar type represents a unicode char. The input and output values are a string, and there can only be one unicode character in this string.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for f32

The Float scalar type represents signed double-precision fractional values as specified by IEEE 754.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for f64

The Float scalar type represents signed double-precision fractional values as specified by IEEE 754.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for i8

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for i16

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for i32

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for i64

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for isize

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for u8

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for u16

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for u32

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for u64

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for usize

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for Bytes

The Binary scalar type represents binary data.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for String

The String scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroI8

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroI16

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroI32

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroI64

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroU8

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroU16

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroU32

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for NonZeroU64

The Int scalar type represents non-fractional whole numeric values.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

Implementors

impl ScalarType for Any

The _Any scalar is used to pass representations of entities from external services into the root _entities field for execution.

impl ScalarType for ID