Mongodb query (hashmap objects)

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") 
  } 
}

Ok, so what have you tried? Fyi: It will need to scan through all documents if the keys aren't fixed and indexed. — WiredPrairie
– WiredPrairie, Commented Mar 26, 2013 at 11:05
I am totally new to mongodb or any NoSql db, so can I index the middle of "string"? in java obj, i know it is a key but how does the mongodb knows that is a key? — Jaxox
– Jaxox, Commented Mar 26, 2013 at 16:35

WiredPrairie · Accepted Answer · 2013-03-26 17:06:18Z

6

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") }
    ]
}

answered Mar 26, 2013 at 17:06

WiredPrairie

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3 Comments

Jaxox Over a year ago

thanks for the help, I will have to look into it how to make my own custom converter for the spring data.

Ryan_DS Over a year ago

What if I want to upsert into the admin field? For example, I want to edit the date or add a new admin field with the date if the admin doesn't already exist?

WiredPrairie Over a year ago

@Ryan_DS-please ask a new question. This answer is nearly 7 years old.

anvarik · Accepted Answer · 2013-03-26 13:30:58Z

0

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

answered Mar 26, 2013 at 13:30

anvarik

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4 Comments

Jaxox Over a year ago

Ok but what about I want to query, 25160228446835585906563830293 from the one column? "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") }

anvarik Over a year ago

then you should define adminsID as following and pass to the code above. It will return you whole data back. String adminsID = "25160228446835585906563830293"

Jaxox Over a year ago

Ok thanks, will try that, so is that possible to use one query instead of two? for admins and users in one query?

anvarik Over a year ago

I did only single queries before, but you can try to add them into a single BasicDBObject and then try to query it.. But then it will be an AND query, not OR

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