mirror of
https://github.com/graphql-python/graphene-django.git
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454b74052e
* Fix backward Relay pagination * linting Co-authored-by: Thomas Leonard <thomas@loftorbital.com>
253 lines
8.1 KiB
Python
253 lines
8.1 KiB
Python
from functools import partial
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import six
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from django.db.models.query import QuerySet
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from graphql_relay.connection.arrayconnection import (
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connection_from_list_slice,
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cursor_to_offset,
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get_offset_with_default,
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offset_to_cursor,
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)
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from promise import Promise
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from graphene import Int, NonNull
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from graphene.relay import ConnectionField, PageInfo
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from graphene.types import Field, List
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from .settings import graphene_settings
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from .utils import maybe_queryset
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class DjangoListField(Field):
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def __init__(self, _type, *args, **kwargs):
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from .types import DjangoObjectType
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if isinstance(_type, NonNull):
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_type = _type.of_type
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# Django would never return a Set of None vvvvvvv
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super(DjangoListField, self).__init__(List(NonNull(_type)), *args, **kwargs)
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assert issubclass(
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self._underlying_type, DjangoObjectType
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), "DjangoListField only accepts DjangoObjectType types"
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@property
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def _underlying_type(self):
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_type = self._type
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while hasattr(_type, "of_type"):
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_type = _type.of_type
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return _type
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@property
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def model(self):
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return self._underlying_type._meta.model
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def get_default_queryset(self):
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return self.model._default_manager.get_queryset()
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@staticmethod
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def list_resolver(
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django_object_type, resolver, default_queryset, root, info, **args
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):
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queryset = maybe_queryset(resolver(root, info, **args))
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if queryset is None:
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queryset = default_queryset
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if isinstance(queryset, QuerySet):
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# Pass queryset to the DjangoObjectType get_queryset method
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queryset = maybe_queryset(django_object_type.get_queryset(queryset, info))
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return queryset
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def get_resolver(self, parent_resolver):
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_type = self.type
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if isinstance(_type, NonNull):
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_type = _type.of_type
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django_object_type = _type.of_type.of_type
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return partial(
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self.list_resolver,
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django_object_type,
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parent_resolver,
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self.get_default_queryset(),
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)
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class DjangoConnectionField(ConnectionField):
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def __init__(self, *args, **kwargs):
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self.on = kwargs.pop("on", False)
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self.max_limit = kwargs.pop(
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"max_limit", graphene_settings.RELAY_CONNECTION_MAX_LIMIT
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)
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self.enforce_first_or_last = kwargs.pop(
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"enforce_first_or_last",
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graphene_settings.RELAY_CONNECTION_ENFORCE_FIRST_OR_LAST,
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)
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kwargs.setdefault("offset", Int())
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super(DjangoConnectionField, self).__init__(*args, **kwargs)
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@property
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def type(self):
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from .types import DjangoObjectType
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_type = super(ConnectionField, self).type
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non_null = False
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if isinstance(_type, NonNull):
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_type = _type.of_type
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non_null = True
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assert issubclass(
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_type, DjangoObjectType
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), "DjangoConnectionField only accepts DjangoObjectType types"
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assert _type._meta.connection, "The type {} doesn't have a connection".format(
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_type.__name__
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)
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connection_type = _type._meta.connection
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if non_null:
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return NonNull(connection_type)
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return connection_type
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@property
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def connection_type(self):
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type = self.type
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if isinstance(type, NonNull):
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return type.of_type
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return type
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@property
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def node_type(self):
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return self.connection_type._meta.node
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@property
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def model(self):
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return self.node_type._meta.model
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def get_manager(self):
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if self.on:
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return getattr(self.model, self.on)
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else:
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return self.model._default_manager
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@classmethod
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def resolve_queryset(cls, connection, queryset, info, args):
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# queryset is the resolved iterable from ObjectType
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return connection._meta.node.get_queryset(queryset, info)
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@classmethod
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def resolve_connection(cls, connection, args, iterable, max_limit=None):
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# Remove the offset parameter and convert it to an after cursor.
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offset = args.pop("offset", None)
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after = args.get("after")
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if offset:
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if after:
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offset += cursor_to_offset(after) + 1
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# input offset starts at 1 while the graphene offset starts at 0
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args["after"] = offset_to_cursor(offset - 1)
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iterable = maybe_queryset(iterable)
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if isinstance(iterable, QuerySet):
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list_length = iterable.count()
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else:
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list_length = len(iterable)
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list_slice_length = (
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min(max_limit, list_length) if max_limit is not None else list_length
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)
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# If after is higher than list_length, connection_from_list_slice
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# would try to do a negative slicing which makes django throw an
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# AssertionError
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after = min(get_offset_with_default(args.get("after"), -1) + 1, list_length)
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if max_limit is not None and "first" not in args:
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if "last" in args:
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args["first"] = list_length
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list_slice_length = list_length
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else:
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args["first"] = max_limit
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connection = connection_from_list_slice(
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iterable[after:],
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args,
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slice_start=after,
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list_length=list_length,
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list_slice_length=list_slice_length,
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connection_type=connection,
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edge_type=connection.Edge,
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pageinfo_type=PageInfo,
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)
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connection.iterable = iterable
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connection.length = list_length
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return connection
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@classmethod
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def connection_resolver(
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cls,
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resolver,
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connection,
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default_manager,
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queryset_resolver,
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max_limit,
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enforce_first_or_last,
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root,
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info,
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**args
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):
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first = args.get("first")
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last = args.get("last")
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offset = args.get("offset")
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before = args.get("before")
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if enforce_first_or_last:
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assert first or last, (
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"You must provide a `first` or `last` value to properly paginate the `{}` connection."
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).format(info.field_name)
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if max_limit:
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if first:
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assert first <= max_limit, (
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"Requesting {} records on the `{}` connection exceeds the `first` limit of {} records."
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).format(first, info.field_name, max_limit)
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args["first"] = min(first, max_limit)
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if last:
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assert last <= max_limit, (
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"Requesting {} records on the `{}` connection exceeds the `last` limit of {} records."
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).format(last, info.field_name, max_limit)
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args["last"] = min(last, max_limit)
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if offset is not None:
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assert before is None, (
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"You can't provide a `before` value at the same time as an `offset` value to properly paginate the `{}` connection."
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).format(info.field_name)
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# eventually leads to DjangoObjectType's get_queryset (accepts queryset)
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# or a resolve_foo (does not accept queryset)
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iterable = resolver(root, info, **args)
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if iterable is None:
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iterable = default_manager
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# thus the iterable gets refiltered by resolve_queryset
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# but iterable might be promise
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iterable = queryset_resolver(connection, iterable, info, args)
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on_resolve = partial(
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cls.resolve_connection, connection, args, max_limit=max_limit
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)
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if Promise.is_thenable(iterable):
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return Promise.resolve(iterable).then(on_resolve)
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return on_resolve(iterable)
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def get_resolver(self, parent_resolver):
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return partial(
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self.connection_resolver,
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parent_resolver,
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self.connection_type,
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self.get_manager(),
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self.get_queryset_resolver(),
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self.max_limit,
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self.enforce_first_or_last,
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)
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def get_queryset_resolver(self):
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return self.resolve_queryset
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