How to get array of document using Mongodb java?

问题

How to get all the document under array in mongodb java. My Database is as below. Want to retrieve all the data under array 198_168_1_134.

below is some of What i tried,

eventlist.find(new BasicDBObject("$match","192_168_10_17"))
eventlist.find(new BasicDBObject("$elemMatch","192_168_10_17"))
eventlist.find(null, new BasicDBObject("$192_168_10_17", 1))

回答1:

You have two options:

• using .find() with cherry-picking which document you have to have fetched.
• using the aggregation framework by projecting the documents.

By using .find() , you can do:

db.collection.find({}, { 192_168_10_17 : 1 })

By using the aggregation framework, you can do:

db.collection.aggregate( { $project : { 192_168_10_17 : 1 } } )

which will fetch only the 192_168_10_17 document data.

Of course, in order to get this working in Java, you have to translate these queries to a corresponding chain of BasicDBObject instances.

回答2:

By using mongo java driver you can do this by following query -

eventlist.find(new BasicDBObject(), new BasicDBObject("198_168_1_134", 1)) 

来源：https://stackoverflow.com/questions/29771457/how-to-get-array-of-document-using-mongodb-java