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 Bson

Available on crate feature bson only.

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

fn to_value(&self) -> Value

impl ScalarType for Tz

Available on crate feature chrono-tz only.

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

fn to_value(&self) -> Value

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 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 BigDecimal

Available on crate feature bigdecimal only.

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

fn to_value(&self) -> Value

impl ScalarType for DateTime

Available on crate feature bson only.

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

fn to_value(&self) -> Value

impl ScalarType for Document

Available on crate feature bson only.

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

fn to_value(&self) -> Value

impl ScalarType for ObjectId

Available on crate feature bson only.

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

fn to_value(&self) -> Value

impl ScalarType for Uuid

Available on crate feature bson only.

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

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 DateTime<FixedOffset>

Available on crate feature chrono only.

Implement the DateTime scalar

The input/output is a string in RFC3339 format.

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

fn to_value(&self) -> Value

impl ScalarType for DateTime<Local>

Available on crate feature chrono only.

Implement the DateTime scalar

The input/output is a string in RFC3339 format.

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

fn to_value(&self) -> Value

impl ScalarType for DateTime<Utc>

Available on crate feature chrono only.

Implement the DateTime scalar

The input/output is a string in RFC3339 format.

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

fn to_value(&self) -> Value

impl ScalarType for NaiveDate

Available on crate feature chrono only.

ISO 8601 calendar date without timezone. Format: %Y-%m-%d

Examples

• 1994-11-13
• 2000-02-24

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

fn to_value(&self) -> Value

impl ScalarType for NaiveDateTime

Available on crate feature chrono only.

ISO 8601 combined date and time without timezone.

Examples

• 2015-07-01T08:59:60.123,

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

fn to_value(&self) -> Value

impl ScalarType for NaiveTime

Available on crate feature chrono only.

ISO 8601 time without timezone. Allows for the nanosecond precision and optional leap second representation. Format: %H:%M:%S%.f

Examples

• 08:59:60.123

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

fn to_value(&self) -> Value

impl ScalarType for Decimal

Available on crate feature decimal only.

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

fn to_value(&self) -> Value

impl ScalarType for SmolStr

Available on crate feature smol_str only.

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

fn is_valid(value: &Value) -> bool

fn to_value(&self) -> Value

impl ScalarType for Date

Available on crate feature time only.

ISO 8601 calendar date without timezone. Format: %Y-%m-%d

Examples

• 1994-11-13
• 2000-02-24

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

fn to_value(&self) -> Value

impl ScalarType for OffsetDateTime

Available on crate feature time only.

A datetime with timezone offset.

The input is a string in RFC3339 format, e.g. “2022-01-12T04:00:19.12345Z” or “2022-01-12T04:00:19+03:00”. The output is also a string in RFC3339 format, but it is always normalized to the UTC (Z) offset, e.g. “2022-01-12T04:00:19.12345Z”.

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

fn to_value(&self) -> Value

impl ScalarType for PrimitiveDateTime

Available on crate feature time only.

A local datetime without timezone offset.

The input/output is a string in ISO 8601 format without timezone, including subseconds. E.g. “2022-01-12T07:30:19.12345”.

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

fn to_value(&self) -> Value

impl ScalarType for Url

Available on crate feature url only.

URL is a String implementing the URL Standard

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

fn to_value(&self) -> Value

impl ScalarType for Uuid

Available on crate feature uuid only.

A UUID is a unique 128-bit number, stored as 16 octets. UUIDs are parsed as Strings within GraphQL. UUIDs are used to assign unique identifiers to entities without requiring a central allocating authority.

References

• Wikipedia: Universally Unique Identifier
• RFC4122: A Universally Unique Identifier (UUID) URN Namespace

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

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 NonZeroIsize

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

impl ScalarType for NonZeroUsize

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 Duration

Available on crate feature chrono-duration only.

Implement the Duration scalar

The input/output is a string in ISO8601 format.

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

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

impl<T: Num + Display + Send + Sync> ScalarType for StringNumber<T>

where <T as Num>::FromStrRadixErr: Display,

Available on crate feature string_number only.