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72 lines
2.2 KiB
Python
72 lines
2.2 KiB
Python
from .base import BaseOptions, BaseType
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from .field import Field
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from .utils import yank_fields_from_attrs
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# For static type checking with Mypy
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MYPY = False
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if MYPY:
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from typing import Dict # NOQA
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class InterfaceOptions(BaseOptions):
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fields = None # type: Dict[str, Field]
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class Interface(BaseType):
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"""
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Interface Type Definition
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When a field can return one of a heterogeneous set of types, a Interface type
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is used to describe what types are possible, what fields are in common across
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all types, as well as a function to determine which type is actually used
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when the field is resolved.
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.. code:: python
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from graphene import Interface, String
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class HasAddress(Interface):
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class Meta:
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description = "Address fields"
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address1 = String()
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address2 = String()
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If a field returns an Interface Type, the ambiguous type of the object can be determined using
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``resolve_type`` on Interface and an ObjectType with ``Meta.possible_types`` or ``is_type_of``.
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Meta:
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name (str): Name of the GraphQL type (must be unique in schema). Defaults to class
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name.
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description (str): Description of the GraphQL type in the schema. Defaults to class
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docstring.
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fields (Dict[str, graphene.Field]): Dictionary of field name to Field. Not recommended to
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use (prefer class attributes).
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"""
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@classmethod
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def __init_subclass_with_meta__(cls, _meta=None, **options):
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if not _meta:
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_meta = InterfaceOptions(cls)
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fields = {}
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for base in reversed(cls.__mro__):
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fields.update(yank_fields_from_attrs(base.__dict__, _as=Field))
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if _meta.fields:
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_meta.fields.update(fields)
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else:
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_meta.fields = fields
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super(Interface, cls).__init_subclass_with_meta__(_meta=_meta, **options)
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@classmethod
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def resolve_type(cls, instance, info):
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from .objecttype import ObjectType
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if isinstance(instance, ObjectType):
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return type(instance)
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def __init__(self, *args, **kwargs):
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raise Exception("An Interface cannot be initialized")
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