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import re
from collections import OrderedDict
try:
from collections.abc import Iterable
except ImportError:
from collections import Iterable
from functools import partial
from graphql_relay import connection_from_list
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
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.",
)
class ConnectionOptions(ObjectTypeOptions):
node = None
class Connection(ObjectType):
class Meta:
abstract = True
@classmethod
def __init_subclass_with_meta__(cls, node=None, name=None, **options):
_meta = ConnectionOptions(cls)
assert node, "You have to provide a node in {}.Meta".format(cls.__name__)
assert isinstance(node, NonNull) or issubclass(
node, (Scalar, Enum, ObjectType, Interface, Union, NonNull)
), ('Received incompatible node "{}" for Connection {}.').format(
node, cls.__name__
)
base_name = re.sub("Connection$", "", name or cls.__name__) or node._meta.name
if not name:
name = "{}Connection".format(base_name)
edge_class = getattr(cls, "Edge", None)
_node = node
class EdgeBase(object):
node = Field(_node, description="The item at the end of the edge")
cursor = String(required=True, description="A cursor for use in pagination")
class EdgeMeta:
description = "A Relay edge containing a `{}` and its cursor.".format(
base_name
)
edge_name = "{}Edge".format(base_name)
if edge_class:
edge_bases = (edge_class, EdgeBase, ObjectType)
else:
edge_bases = (EdgeBase, ObjectType)
edge = type(edge_name, edge_bases, {"Meta": EdgeMeta})
cls.Edge = edge
options["name"] = name
_meta.node = node
_meta.fields = OrderedDict(
[
(
"page_info",
Field(
PageInfo,
name="pageInfo",
required=True,
description="Pagination data for this connection.",
),
),
(
"edges",
Field(
NonNull(List(edge)),
description="Contains the nodes in this connection.",
),
),
]
)
return super(Connection, cls).__init_subclass_with_meta__(
_meta=_meta, **options
)
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), (
'{} type have to be a subclass of Connection. Received "{}".'
).format(self.__class__.__name__, connection_type)
return type
@classmethod
def resolve_connection(cls, connection_type, args, resolved):
if isinstance(resolved, connection_type):
return resolved
assert isinstance(resolved, Iterable), (
"Resolved value from the connection field have to be iterable or instance of {}. "
'Received "{}"'
).format(connection_type, resolved)
connection = connection_from_list(
resolved,
args,
connection_type=connection_type,
edge_type=connection_type.Edge,
pageinfo_type=PageInfo,
)
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 get_resolver(self, parent_resolver):
resolver = super(IterableConnectionField, self).get_resolver(parent_resolver)
return partial(self.connection_resolver, resolver, self.type)
ConnectionField = IterableConnectionField
|
