在MongoDB中，如何获取嵌入文档字段中的值，但根据不同的值进行查询
我有一个像这样的基本结构：
> db.users.findOne()
{
"_id" : ObjectId("4f384903cd087c6f720066d7"),
"current_sign_in_at" : ISODate("2012-02-12T23:19:31Z"),
"current_sign_in_ip" : "127.0.0.1",
"email" : "[email protected]",
"encrypted_password" : "$2a$10$fu9B3M/.Gmi8qe7pXtVCPu94mBVC.gn5DzmQXH.g5snHT4AJSZYCu",
"last_sign_in_at" : ISODate("2012-02-12T23:19:31Z"),
"last_sign_in_ip" : "127.0.0.1",
"name" : "Trip Jameson",
"sign_in_count" : 100,
"usertimes" : [
...thousands and thousands of records like this one....
{
"enddate" : 348268392.115282,
"idle" : 0,
"startdate" : 348268382.116728,
"title" : "My Awesome Title"
},
]
}
所以我只想找到标题为“My Awesome Title”的单个用户的用户时间，然后我想看看该记录中“idle”的值是多少
所以我所能想到的是，我可以通过如下搜索找到整个用户记录：
> db.users.find({'usertimes.title':"My Awesome Title"})
但这只是返回整个用户记录，这对我的目的来说毫无用处。我误解了什么吗？
I have a basic structure like this:
> db.users.findOne()
{
"_id" : ObjectId("4f384903cd087c6f720066d7"),
"current_sign_in_at" : ISODate("2012-02-12T23:19:31Z"),
"current_sign_in_ip" : "127.0.0.1",
"email" : "[email protected]",
"encrypted_password" : "$2a$10$fu9B3M/.Gmi8qe7pXtVCPu94mBVC.gn5DzmQXH.g5snHT4AJSZYCu",
"last_sign_in_at" : ISODate("2012-02-12T23:19:31Z"),
"last_sign_in_ip" : "127.0.0.1",
"name" : "Trip Jameson",
"sign_in_count" : 100,
"usertimes" : [
...thousands and thousands of records like this one....
{
"enddate" : 348268392.115282,
"idle" : 0,
"startdate" : 348268382.116728,
"title" : "My Awesome Title"
},
]
}
So I want to find only usertimes for a single user where the title was "My Awesome Title", and then I want to see what the value for "idle" was in that record(s)
So far all I can figure out is that I can find the entire user record with a search like:
> db.users.find({'usertimes.title':"My Awesome Title"})
This just returns the entire User record though, which is useless for my purposes. Am I misunderstanding something?
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MongoDB 目前不支持仅返回部分嵌入文档
匹配的用户记录将始终被返回（至少对于当前的 MongoDB 版本）。
请参阅此问题以获取类似的参考
Filtering嵌入文档在MongoDB中
这是MongoDB上的对应Jira空格
http://jira.mongodb.org/browse/SERVER-142
Return only partial embedded documents is currently not supported by MongoDB
The matching User record will always be returned (at least with the current MongoDB version).
see this question for similar reference
Filtering embedded documents in MongoDB
This is the correspondent Jira on MongoDB space
http://jira.mongodb.org/browse/SERVER-142
使用：
db.users.find({'usertimes.title': "My Awesome Title"}, {'idle': 1});我建议您更详细地查看http://www.mongodb.org/display/DOCS/Querying，它会解释一些事情为你。
Use:
db.users.find({'usertimes.title': "My Awesome Title"}, {'idle': 1});May I suggest you take a more detailed look at http://www.mongodb.org/display/DOCS/Querying, it'll explain things for you.