graphene-django/graphene_django/fields.py

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from functools import partial
from django.db.models.query import QuerySet
from promise import Promise
from graphene.types import Field, List
from graphene.relay import ConnectionField, PageInfo
from graphql_relay.connection.arrayconnection import connection_from_list_slice
from .settings import graphene_settings
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from .utils import maybe_queryset
class DjangoListField(Field):
def __init__(self, _type, *args, **kwargs):
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super(DjangoListField, self).__init__(List(_type), *args, **kwargs)
@property
def model(self):
return self.type.of_type._meta.node._meta.model
@staticmethod
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def list_resolver(resolver, root, info, **args):
return maybe_queryset(resolver(root, info, **args))
def get_resolver(self, parent_resolver):
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return partial(self.list_resolver, parent_resolver)
class DjangoConnectionField(ConnectionField):
def __init__(self, *args, **kwargs):
self.on = kwargs.pop('on', False)
self.max_limit = kwargs.pop(
'max_limit',
graphene_settings.RELAY_CONNECTION_MAX_LIMIT
)
self.enforce_first_or_last = kwargs.pop(
'enforce_first_or_last',
graphene_settings.RELAY_CONNECTION_ENFORCE_FIRST_OR_LAST
)
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super(DjangoConnectionField, self).__init__(*args, **kwargs)
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@property
def type(self):
from .types import DjangoObjectType
_type = super(ConnectionField, self).type
assert issubclass(_type, DjangoObjectType), "DjangoConnectionField only accepts DjangoObjectType types"
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assert _type._meta.connection, "The type {} doesn't have a connection".format(_type.__name__)
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return _type._meta.connection
@property
def node_type(self):
return self.type._meta.node
@property
def model(self):
return self.node_type._meta.model
def get_manager(self):
if self.on:
return getattr(self.model, self.on)
else:
return self.model._default_manager
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@classmethod
def merge_querysets(cls, default_queryset, queryset):
return queryset & default_queryset
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@classmethod
def resolve_connection(cls, connection, default_manager, args, iterable):
if iterable is None:
iterable = default_manager
iterable = maybe_queryset(iterable)
if isinstance(iterable, QuerySet):
if iterable is not default_manager:
default_queryset = maybe_queryset(default_manager)
iterable = cls.merge_querysets(default_queryset, iterable)
_len = iterable.count()
else:
_len = len(iterable)
connection = connection_from_list_slice(
iterable,
args,
slice_start=0,
list_length=_len,
list_slice_length=_len,
connection_type=connection,
edge_type=connection.Edge,
pageinfo_type=PageInfo,
)
connection.iterable = iterable
connection.length = _len
return connection
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@classmethod
def connection_resolver(cls, resolver, connection, default_manager, max_limit,
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enforce_first_or_last, root, info, **args):
first = args.get('first')
last = args.get('last')
if enforce_first_or_last:
assert first or last, (
'You must provide a `first` or `last` value to properly paginate the `{}` connection.'
).format(info.field_name)
if max_limit:
if first:
assert first <= max_limit, (
'Requesting {} records on the `{}` connection exceeds the `first` limit of {} records.'
).format(first, info.field_name, max_limit)
args['first'] = min(first, max_limit)
if last:
assert last <= max_limit, (
'Requesting {} records on the `{}` connection exceeds the `last` limit of {} records.'
).format(first, info.field_name, max_limit)
args['last'] = min(last, max_limit)
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iterable = resolver(root, info, **args)
on_resolve = partial(cls.resolve_connection, connection, default_manager, args)
if Promise.is_thenable(iterable):
return Promise.resolve(iterable).then(on_resolve)
return on_resolve(iterable)
def get_resolver(self, parent_resolver):
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return partial(
self.connection_resolver,
parent_resolver,
self.type,
self.get_manager(),
self.max_limit,
self.enforce_first_or_last
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)