http://blog.csdn.net/littlethunder/article/details/9748519
http://gaopenghigh.iteye.com/blog/1483864
sorted(b, key = lambda b : b['order'])
1. target_order > now_order
oDict = [.....] #已经通过排序
for i in range(now_order+1, target_order+1) #下标
db.coll.update({'_id': oDict[i-1]['_id']}, {'order': i-1})
db.coll.update({'_id': 页面上操作地元素的id, 'order': targer_order})
2. now_orde > rtarget_order
oDict = [.....] #已经通过排序
for i in range(target_order, now_order) #下标
db.coll.update({'_id': oDict[i-1]['_id']}, {'order': i-1})
db.coll.update({'_id': 页面上操作地元素的id, 'order': targer_order})