Mongodb query (hashmap objects) - mongodb

Question

I want to query all the UserGroup's ID where admins's ID="25160228446835585906563830293" or users's ID ="25160228446835585906563830293".
this is a hashmap key and value pair in java obj hashmap<String,Date>
"25160228446835585906563830293" : ISODate("2013-03-26T04:51:36.731Z")
{ "_id" : ObjectId("51512958849ca4748271c640"),
"_class" : "com.pcd.app.model.UserGroup",
"groupName" : "sdfsadfsad",
"privacyType" : "PRIVACY_OPEN",
"approvalType" : "MEMBER_APPROVAL",
"groupDescription" : "test",
"admins" : {
"25160228446835585906563830293" : ISODate("2013-03-26T04:51:36.731Z"),
"25160228446835585906563830294" : ISODate("2013-03-26T04:51:36.731Z"),
"25160228446835585906563830295" : ISODate("2013-03-26T04:51:36.731Z")
},
"users" : {
"25160228446835585906563830296" : ISODate("2013-03-26T04:51:36.731Z")
}
}

Answer 1

I'd suggest you restructure your document to make it indexable and more easily searched in MongoDB.
Instead of using the id of the admin as a field, add each admin as an object of an array:
"admins" : [
{ id: "25160228446835585906563830293",
date: ISODate("2013-03-26T04:51:36.731Z") }
],
This will make searches more natural:
db.so.find( { "admins.id" :
{ $in: ['25160228446835585906563830293',
'25160228446835585906563830296']}})
You can use the $in (docs) operator to look for admins with an id that matches the list as you wanted (admins.id).
So, given a Java QueryBuilder, it might look something like this:
BasicDBList adminIds = new BasicDBList();
adminIds.addAll(ids); // the ids could be a List<String>
DBObject inClause = new BasicDBObject("$in", adminIds);
DBObject query = new BasicDBObject("admins.id", inClause);
You may want to use ensureIndex to build an index (docs).
Based on your original example, here's the full document for reference:
{
"_id" : ObjectId("51512958849ca4748271c640"),
"_class" : "com.pcd.app.model.UserGroup",
"groupName" : "sdfsadfsad",
"privacyType" : "PRIVACY_OPEN",
"approvalType" : "MEMBER_APPROVAL",
"groupDescription" : "test",
"admins" : [
{ id: "25160228446835585906563830293" ,
date: ISODate("2013-03-26T04:51:36.731Z") },
{ id: "25160228446835585906563830294" ,
date: ISODate("2013-03-26T04:51:36.731Z") },
{ id: "25160228446835585906563830295" ,
date: ISODate("2013-03-26T04:51:36.731Z") }
],
"users" : [
{ id: "25160228446835585906563830296",
date : ISODate("2013-03-26T04:51:36.731Z") }
]
}

Answer 2

If you are using mongodb java driver you can do the following:
BasicDBObject queryForAdminsID = new BasicDBObject("admins." + adminsID, new BasicDBObject("$exists", true));
// BasicDBObject queryForUsersID = new BasicDBObject("users." + usersID, new BasicDBObject("$exists", true));
cursor = coll.find(query); // coll is a DBCollection
try {
while(cursor.hasNext()) {
System.out.println(cursor.next());
}
} finally {
cursor.close();
}
where usersID and adminsID are your ids