# -*- coding: utf-8 -*-
from bson.dbref import DBRef
from mongoengine.base import get_document
from mongoengine.connection import get_db
from mongoengine.dereference import DeReference
from .document import Document, EmbeddedDocument, TopLevelDocumentMetaclass
from .fields import ReferenceField, ListField, DictField, MapField
from .queryset import QuerySet
[docs]
class MongoMotorDeReference(DeReference):
async def __call__(self, items, max_depth=1, instance=None, name=None):
"""
Cheaply dereferences the items to a set depth.
Also handles the conversion of complex data types.
:param items: The iterable (dict, list, queryset) to be dereferenced.
:param max_depth: The maximum depth to recurse to
:param instance: The owning instance used for tracking changes by
:class:`~mongomotor.ComplexBaseField`
:param name: The name of the field, used for tracking changes by
:class:`~mongomotor.ComplexBaseField`
:param get: A boolean determining if being called by __get__
"""
if items is None or isinstance(items, str):
return items
if isinstance(items, QuerySet):
items = await items.to_list()
self.max_depth = max_depth
doc_type = None
if instance and isinstance(
instance, (Document, EmbeddedDocument, TopLevelDocumentMetaclass)
):
items, doc_type = self._get_deref_items_for_instance(
instance, items, name)
self.reference_map = self._find_references(items)
self.object_map = await self._fetch_objects(doc_type=doc_type)
return self._attach_objects(items, 0, instance, name)
async def _fetch_objects(self, doc_type=None):
"""Fetch all references and convert to their document objects"""
object_map = {}
for collection, dbrefs in self.reference_map.items():
# we use getattr instead of hasattr because hasattr swallows
# any exception under python2
# so it could hide nasty things without raising
# exceptions (cfr bug #1688))
ref_document_cls_exists = getattr(
collection, "objects", None) is not None
if ref_document_cls_exists:
col_name = collection._get_collection_name()
refs = [
dbref for dbref in dbrefs if (col_name, dbref)
not in object_map
]
references = await collection.objects.in_bulk(refs)
for key, doc in references.items():
object_map[(col_name, key)] = doc
else:
# Generic reference: use the refs data to convert to document
if isinstance(doc_type, (ListField, DictField, MapField)):
continue
refs = [
dbref for dbref in dbrefs if (collection, dbref)
not in object_map
]
if doc_type:
references = doc_type._get_db()[collection].find(
{"_id": {"$in": refs}}
)
async for ref in references:
doc = doc_type._from_son(ref)
object_map[(collection, doc.id)] = doc
else:
references = get_db()[collection].find(
{"_id": {"$in": refs}})
async for ref in references:
if "_cls" in ref:
doc = get_document(ref["_cls"])._from_son(ref)
elif doc_type is None:
doc = get_document(
"".join(x.capitalize()
for x in collection.split("_"))
)._from_son(ref)
else:
doc = doc_type._from_son(ref)
object_map[(collection, doc.id)] = doc
return object_map
def _get_deref_items_for_instance(self, instance, items, name):
doc_type = instance._fields.get(name)
while hasattr(doc_type, "field"):
doc_type = doc_type.field
if not isinstance(doc_type, ReferenceField):
return items, doc_type
field = doc_type
doc_type = doc_type.document_type
is_list = not hasattr(items, "items")
if is_list and all(i.__class__ == doc_type for i in items):
return items, doc_type
elif not is_list and all(
i.__class__ == doc_type for i in items.values()
):
return items, doc_type
elif not field.dbref:
# We must turn the ObjectIds into DBRefs
# Recursively dig into the sub items of a list/dict
# to turn the ObjectIds into DBRefs
if not hasattr(items, "items"):
items = _get_items_from_list(field, items)
else:
items = _get_items_from_dict(field, items)
return items, doc_type
def _get_items_from_list(field, items):
new_items = []
for v in items:
value = v
if isinstance(v, dict):
value = _get_items_from_dict(v)
elif isinstance(v, list):
value = _get_items_from_list(v)
elif not isinstance(v, (DBRef, Document)):
value = field.to_python(v)
new_items.append(value)
return new_items
def _get_items_from_dict(field, items):
new_items = {}
for k, v in items.items():
value = v
if isinstance(v, list):
value = _get_items_from_list(v)
elif isinstance(v, dict):
value = _get_items_from_dict(v)
elif not isinstance(v, (DBRef, Document)):
value = field.to_python(v)
new_items[k] = value
return new_items
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