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52 lines
1.5 KiB
Python
52 lines
1.5 KiB
Python
from collections import OrderedDict
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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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'''
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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 = OrderedDict()
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for base in reversed(cls.__mro__):
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fields.update(
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yank_fields_from_attrs(base.__dict__, _as=Field)
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)
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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 intitialized")
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