如何获得mongodb中的嵌套对象值？

Question

如何在集合中执行筛选。例如，我收集了这样的数据，我想做这个rits_dbx_1>0.2,simon_dbx_1<0.5

{
   "threads":{
      "threads_participants":{
         "participant":[
            {
               "@all_user_n_grams":"0",
               "@reference":"rits_dbx_2",
               "overall_user_participation":"0.0",
               "thread":{
                  "@thread_id":"5e778ea6a28f9a3881c330b4",
                  "#text":"{'relative_to_thread_interactors': 0.0, 'relative_to_self_threads': 0}"
               }
            },
            {
               "@all_user_n_grams":"11",
               "@reference":"rits_dbx_1",
               "overall_user_participation":"1.0",
               "thread":{
                  "@thread_id":"5e778ea6a28f9a3881c330b4",
                  "#text":"{'relative_to_thread_interactors': 1.0, 'relative_to_self_threads': 1.0}"
               }
            }
         ]
      }
   }
}

首先，我尝试使用find方法获得值。

 db.xml_collection.find({"threads.threads_participants.participant": {"@reference": "rits_dbx_2"}})

它也什么也没回。你能帮上忙吗？

Answer 1

我知道你你想要找到

"@reference":"rits_dbx_2“和"overall_user_participation":"$gt":0.5

或

@reference：“simon_dbx_1”和"overall_user_participation":"$lt":0.2

如果是的话：

list(db.xml_collection.find({"$or": [{"threads.threads_participants.participant.@reference":"rits_dbx_2","threads.threads_participants.participant.overall_user_participation":{"$gt":"0.2"}},{"threads.threads_participants.participant.@reference":"simon_dbx_1","threads.threads_participants.participant.overall_user_participation":{"$lt":"0.2"}}]}))

我还建议您在overall_user_participation字段中使用浮点数而不是字符串来提高比较性能和正确性。