Delete fields from array in mongodb using java driver

Question

I need delete all fields from the devices array they have the condition where state = 0

And this is my mongodb document:

{ "_id" : { "$oid" : "53e53553b76000127cb1ab80"} ,  
  "city" : "Some Place" , 
  "devices" : 
       [ { "guid" : "local" , "brand" : "SSSS" , "state" : 1} , 
         { "guid" : "local2" , "brand" : "DDD" , "state" : 0} , 
         { "guid" : "local2" , "brand" : "DDD" , "state" : 0} ,   
         { "guid" : "local2" , "brand" : "DDD" , "state" : 0}] , 
  "phone": 8888888888,   
  "sex" : "Male"
 }

This is my java code that I'm trying:

DBCollection collection = db.getCollection(usersCollection);
BasicDBObject query2 = new BasicDBObject("_id", id);
((BasicDBObject) query2).append("devices.guid", device);
((BasicDBObject) query2).append("devices.state", 0);
collection.remove(query2);

But this query delete all devices from the document. Thanks in advance!

u3l · Accepted Answer · 2014-08-09 04:28:05Z

2

You need to do the equivalent of:

db.usersCollection.update(
     {"_id":"yourId"}, 
     {$pull: 
            { "devices" : 
                    { $elemMatch : 
                        {
                          "guid":"local2", 
                          "state":"0"
                        }
                    }
            }
     }
)

Where you replace the yourId with the ID you want to query

That is, instead of using remove, use update, with $pull in the BasicDBObject. I can't test this right now but try:

DBCollection collection = db.getCollection(usersCollection);
BasicDBObject query = new BasicDBObject("_id", id);

BasicDBObject deviceToDelete = new BasicDBObject("guid",device);
deviceToDelete.append("state", "0");

BasicDBObject obj = new BasicDBObject("devices", deviceToDelete);
collection.update(query, new BasicDBObject("$pull",obj));

Let me know if this works (again I can't test because I don't have mongod on my machine).

edited Aug 9, 2014 at 4:28

answered Aug 8, 2014 at 21:43

u3l

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8 Comments

hcarrasko Over a year ago

Thanks for your help but this doesn't delete anything in the document :/

u3l Over a year ago

What is the value of device (the variable you're passing into the BasicDBObject)?

hcarrasko Over a year ago

Is "local2", corresponding to guid field

u3l Over a year ago

Can you tell me the output of printing collection.findOne(query)?

hcarrasko Over a year ago

I replace for it: db.usuario.findOne({devices:{"guid":"local2", "state":0}}) and get it : null

|

Community · Accepted Answer · 2017-05-23 12:19:26Z

1

I fix the problem following this answer

This code works:

    DBCollection collection = db.getCollection(usersCollection);
    BasicDBObject match = new BasicDBObject("_id", id);
    BasicDBObject update2 = new BasicDBObject("devices", new BasicDBObject("guid", device)
                                      .append("state", 0));
    collection.update(match, new BasicDBObject("$pull", update2));

edited May 23, 2017 at 12:19

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answered Aug 11, 2014 at 14:52

hcarrasko

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2 Comments

u3l Over a year ago

I'm sorry if I'm mistaken, but that seems to be exactly what I wrote, except you declared the BasicDBObject containing guid and state inside the update2 initialization, whereas I created the object and then put it into update2. Either way, it has an identical outcome. (Sorry if I missed something though, congrats on getting the answer!)

hcarrasko Over a year ago

@Trust sorry but you answer was not useful to me.

ProMisDev · Accepted Answer · 2014-08-18 13:45:21Z

You cannot use the remove-Function to remove a embeded document, you need to use update instead. This is the function call you need to implement in java:

db.userCollection.update(
{_id: ObjectId("53e53553b76000127cb1ab80")},
{$pull: 
    { devices : 
            {state: 0}
    }
})

Notice that the update-function takes to arguments, the first one to find the document and the second one to modify it.

DBCollection collection = db.getCollection(usersCollection);
BasicDBObject query = new BasicDBObject("_id", newObjectID("53e53553b76000127cb1ab80"));

BasicDBObject condition = new BasicDBObject("state",0);
BasicDBObject array = new BasicDBObject("devices", condition);
BasicDBObject update = new BasicDBObject("$pull", array);

collection.update(query, update);

I didn't test the Java Code but I tested the function call in mongoDB. If it doesn't work, check the implementation first.

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