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import re
from collections.abc import Iterable
from functools import partial
from typing import Type
from graphql_relay import connection_from_array
from ..types import Boolean, Enum, Int, Interface, List, NonNull, Scalar, String, Union
from ..types.field import Field
from ..types.objecttype import ObjectType, ObjectTypeOptions
from ..utils.thenables import maybe_thenable
from .node import is_node, AbstractNode
def get_edge_class(
connection_class: Type["Connection"],
_node: Type[AbstractNode],
base_name: str,
strict_types: bool = False,
):
edge_class = getattr(connection_class, "Edge", None)
class EdgeBase:
node = Field(
NonNull(_node) if strict_types else _node,
description="The item at the end of the edge",
)
cursor = String(required=True, description="A cursor for use in pagination")
class EdgeMeta:
description = f"A Relay edge containing a `{base_name}` and its cursor."
edge_name = f"{base_name}Edge"
edge_bases = [edge_class, EdgeBase] if edge_class else [EdgeBase]
if not isinstance(edge_class, ObjectType):
edge_bases = [*edge_bases, ObjectType]
return type(edge_name, tuple(edge_bases), {"Meta": EdgeMeta})
class PageInfo(ObjectType):
class Meta:
description = (
"The Relay compliant `PageInfo` type, containing data necessary to"
" paginate this connection."
)
has_next_page = Boolean(
required=True,
name="hasNextPage",
description="When paginating forwards, are there more items?",
)
has_previous_page = Boolean(
required=True,
name="hasPreviousPage",
description="When paginating backwards, are there more items?",
)
start_cursor = String(
name="startCursor",
description="When paginating backwards, the cursor to continue.",
)
end_cursor = String(
name="endCursor",
description="When paginating forwards, the cursor to continue.",
)
# noinspection PyPep8Naming
def page_info_adapter(startCursor, endCursor, hasPreviousPage, hasNextPage):
"""Adapter for creating PageInfo instances"""
return PageInfo(
start_cursor=startCursor,
end_cursor=endCursor,
has_previous_page=hasPreviousPage,
has_next_page=hasNextPage,
)
class ConnectionOptions(ObjectTypeOptions):
node = None
class Connection(ObjectType):
class Meta:
abstract = True
@classmethod
def __init_subclass_with_meta__(
cls, node=None, name=None, strict_types=False, _meta=None, **options
):
if not _meta:
_meta = ConnectionOptions(cls)
assert node, f"You have to provide a node in {cls.__name__}.Meta"
assert isinstance(node, NonNull) or issubclass(
node, (Scalar, Enum, ObjectType, Interface, Union, NonNull)
), f'Received incompatible node "{node}" for Connection {cls.__name__}.'
base_name = re.sub("Connection$", "", name or cls.__name__) or node._meta.name
if not name:
name = f"{base_name}Connection"
options["name"] = name
_meta.node = node
if not _meta.fields:
_meta.fields = {}
if "page_info" not in _meta.fields:
_meta.fields["page_info"] = Field(
PageInfo,
name="pageInfo",
required=True,
description="Pagination data for this connection.",
)
if "edges" not in _meta.fields:
edge_class = get_edge_class(cls, node, base_name, strict_types) # type: ignore
cls.Edge = edge_class
_meta.fields["edges"] = Field(
NonNull(List(NonNull(edge_class) if strict_types else edge_class)),
description="Contains the nodes in this connection.",
)
return super(Connection, cls).__init_subclass_with_meta__(
_meta=_meta, **options
)
# noinspection PyPep8Naming
def connection_adapter(cls, edges, pageInfo):
"""Adapter for creating Connection instances"""
return cls(edges=edges, page_info=pageInfo)
class IterableConnectionField(Field):
def __init__(self, type_, *args, **kwargs):
kwargs.setdefault("before", String())
kwargs.setdefault("after", String())
kwargs.setdefault("first", Int())
kwargs.setdefault("last", Int())
super(IterableConnectionField, self).__init__(type_, *args, **kwargs)
@property
def type(self):
type_ = super(IterableConnectionField, self).type
connection_type = type_
if isinstance(type_, NonNull):
connection_type = type_.of_type
if is_node(connection_type):
raise Exception(
"ConnectionFields now need a explicit ConnectionType for Nodes.\n"
"Read more: https://github.com/graphql-python/graphene/blob/v2.0.0/UPGRADE-v2.0.md#node-connections"
)
assert issubclass(
connection_type, Connection
), f'{self.__class__.__name__} type has to be a subclass of Connection. Received "{connection_type}".'
return type_
@classmethod
def resolve_connection(cls, connection_type, args, resolved):
if isinstance(resolved, connection_type):
return resolved
assert isinstance(resolved, Iterable), (
f"Resolved value from the connection field has to be an iterable or instance of {connection_type}. "
f'Received "{resolved}"'
)
connection = connection_from_array(
resolved,
args,
connection_type=partial(connection_adapter, connection_type),
edge_type=connection_type.Edge,
page_info_type=page_info_adapter,
)
connection.iterable = resolved
return connection
@classmethod
def connection_resolver(cls, resolver, connection_type, root, info, **args):
resolved = resolver(root, info, **args)
if isinstance(connection_type, NonNull):
connection_type = connection_type.of_type
on_resolve = partial(cls.resolve_connection, connection_type, args)
return maybe_thenable(resolved, on_resolve)
def wrap_resolve(self, parent_resolver):
resolver = super(IterableConnectionField, self).wrap_resolve(parent_resolver)
return partial(self.connection_resolver, resolver, self.type)
ConnectionField = IterableConnectionField
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