graphene/docs/types/scalars.rst
2017-11-29 14:32:17 +01:00

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Scalars
=======
Graphene defines the following base Scalar Types:
- ``graphene.String``
- ``graphene.Int``
- ``graphene.Float``
- ``graphene.Boolean``
- ``graphene.ID``
Graphene also provides custom scalars for Dates, Times, and JSON:
- ``graphene.types.datetime.Date``
- ``graphene.types.datetime.DateTime``
- ``graphene.types.datetime.Time``
- ``graphene.types.json.JSONString``
Custom scalars
--------------
You can create custom scalars for your schema.
The following is an example for creating a DateTime scalar:
.. code:: python
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
``Field``\ s.
.. code:: python
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 ``Argument``\ s.
.. code:: python
graphene.Field(graphene.String, to=graphene.String())
# Is equivalent to:
graphene.Field(graphene.String, to=graphene.Argument(graphene.String))