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94 lines (75 loc) · 2.93 KB
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# coding: utf-8
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
import leancloud
from leancloud import operation
__author__ = "asaka <lan@leancloud.rocks>"
class Relation(object):
def __init__(self, parent, key=None):
self.parent = parent
self.key = key
self.target_class_name = None
@classmethod
def reverse_query(cls, parent_class, relation_key, child):
"""
创建一个新的 Query 对象，反向查询所有指向此 Relation 的父对象。
:param parent_class: 父类名称
:param relation_key: 父类中 Relation 的字段名
:param child: 子类对象
:return: leancloud.Query
"""
q = leancloud.Query(parent_class)
q.equal_to(relation_key, child._to_pointer())
return q
def _ensure_parent_and_key(self, parent=None, key=None):
if self.parent is None:
self.parent = parent
if self.key is None:
self.key = key
if self.parent != parent:
raise TypeError("relation retrieved from two different object")
if self.key != key:
raise TypeError("relation retrieved from two different object")
def add(self, *obj_or_objs):
"""
添加一个新的 leancloud.Object 至 Relation。
:param obj_or_objs: 需要添加的对象或对象列表
"""
objs = obj_or_objs
if not isinstance(obj_or_objs, (list, tuple)):
objs = (obj_or_objs,)
change = operation.Relation(objs, ())
self.parent.set(self.key, change)
self.target_class_name = change._target_class_name
def remove(self, *obj_or_objs):
"""
从一个 Relation 中删除一个 leancloud.Object 。
:param obj_or_objs: 需要删除的对象或对象列表
:return:
"""
objs = obj_or_objs
if not isinstance(obj_or_objs, (list, tuple)):
objs = (obj_or_objs,)
change = operation.Relation((), objs)
self.parent.set(self.key, change)
self.target_class_name = change._target_class_name
def dump(self):
return {"__type": "Relation", "className": self.target_class_name}
@property
def query(self):
"""
获取指向 Relation 内容的 Query 对象。
:rtype: leancloud.Query
"""
if self.target_class_name is None:
target_class = leancloud.Object.extend(self.parent._class_name)
query = leancloud.Query(target_class)
query._extra["redirectClassNameForKey"] = self.key
else:
target_class = leancloud.Object.extend(self.target_class_name)
query = leancloud.Query(target_class)
query._add_condition("$relatedTo", "object", self.parent._to_pointer())
query._add_condition("$relatedTo", "key", self.key)
return query