Source code for graphene.types.interface

from .base import BaseOptions, BaseType
from .field import Field
from .utils import yank_fields_from_attrs

# For static type checking with Mypy
MYPY = False
if MYPY:
    from typing import Dict, Iterable, Type  # NOQA

class InterfaceOptions(BaseOptions):
    fields = None  # type: Dict[str, Field]
    interfaces = ()  # type: Iterable[Type[Interface]]

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