Scalars

All Scalar types accept the following arguments. All are optional:

name: string

Override the name of the Field.

description: string

A description of the type to show in the GraphiQL browser.

required: boolean

If True, the server will enforce a value for this field. See NonNull. Default is False.

deprecation_reason: string

Provide a deprecation reason for the Field.

default_value: any

Provide a default value for the Field.

Base scalars

Graphene defines the following base Scalar Types:

graphene.String

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.

graphene.Int

Represents non-fractional signed whole numeric values. Int can represent values between -(2^53 - 1) and 2^53 - 1 since represented in JSON as double-precision floating point numbers specified by IEEE 754.

graphene.Float

Represents signed double-precision fractional values as specified by IEEE 754.

graphene.Boolean

Represents true or false.

graphene.ID

Represents a unique identifier, often used to refetch an object or as key for a cache. The ID type appears in a JSON response as a String; however, it is not intended to be human-readable. When expected as an input type, any string (such as “4”) or integer (such as 4) input value will be accepted as an ID.

Graphene also provides custom scalars for Dates, Times, and JSON:

graphene.types.datetime.Date

Represents a Date value as specified by iso8601.

graphene.types.datetime.DateTime

Represents a DateTime value as specified by iso8601.

graphene.types.datetime.Time

Represents a Time value as specified by iso8601.

graphene.types.json.JSONString

Represents a JSON string.

Custom scalars

You can create custom scalars for your schema. The following is an example for creating a DateTime scalar:

import datetime
from graphene.types import Scalar
from graphql.language import ast

class DateTime(Scalar):
    '''DateTime Scalar Description'''

    @staticmethod
    def serialize(dt):
        return dt.isoformat()

    @staticmethod
    def parse_literal(node):
        if isinstance(node, ast.StringValue):
            return datetime.datetime.strptime(
                node.value, "%Y-%m-%dT%H:%M:%S.%f")

    @staticmethod
    def parse_value(value):
        return datetime.datetime.strptime(value, "%Y-%m-%dT%H:%M:%S.%f")

Mounting Scalars

Scalars mounted in a ObjectType, Interface or Mutation act as Fields.

class Person(graphene.ObjectType):
    name = graphene.String()

# Is equivalent to:
class Person(graphene.ObjectType):
    name = graphene.Field(graphene.String)

Note: when using the Field constructor directly, pass the type and not an instance.

Types mounted in a Field act as Arguments.

graphene.Field(graphene.String, to=graphene.String())

# Is equivalent to:
graphene.Field(graphene.String, to=graphene.Argument(graphene.String))