Delete fields from array in mongodb using java driver - mongodb-query

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!

Answer 1

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).

Answer 2

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));

Answer 3

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.