MongoDB CDriver how to update array object in index N?

Question

i have document that looks like this :

{
    "_id" : ObjectId("5768e43"),
    "APPID" : {
        "Number" : 0,
    },
    sessions : [{
            id : 111111,
            "setOID" : {
                "Number" : 0
            },
            "custID" : {
                "Number" : 0
            },

        }, {
            id : 133333,
            "setOID" : {
                "Number" : 2
            },
            "custID" : {
                "Number" : 2
            },
        }, {
            id : 7777,
            "setOID" : {
                "Number" : 2
            },
            "custID" : {
                "Number" : 2
            },

        },
    ]
}

I like to get the sessions elment which its id == 133333 ( which is in [1] ) and be able to update it with new values and add new elements to it so it will look like this :

{
    id : 133333,
    "setOID" : {
        "Number" : 3333

    },
    "custID" : {
        "Number" : 4444

    },
    new_attr_1 : 0
    new_attr_2 : 2
},

The documentation is very hard to understand when it comes to C Driver can someone please show what it the best way to do it ?

UPDATE
I tried with cdriver version 1.4 ( latest ) and weird thing is happening the update did failed ( returend true ) but there is no update in the document

 bson_t *query2 = BCON_NEW ("sessions.id ", BCON_INT32 (133333));    
 bson_t *update;

update = BCON_NEW ("$set", "{","Sessions.$.new_attr_1" ,BCON_INT32 (0) ,"}");

if (!mongoc_collection_update (collection,MONGOC_UPDATE_NONE, query2, update, NULL, &error)) {
    fprintf (stderr, "%s\n", error.message);
    goto fail;
}

so as you see allot of strange things happening , how can i check if update is really successful ?

Answer 1

To answer your question here is a solution :

db.doc.update({"sessions.id":133333},
              {$set: {"sessions.$.setOID.Number":3333,
                      "sessions.$.custID.Number":4444,
                      "sessions.$.new_attr_1" : 0,
                      "sessions.$.new_attr_2" : 2
                     }
              })

And with the C Drive should be something like that :

static void updateSession( mongo_connection *conn ) {
  bson cond[1], op[1];

  bson_init( cond );
    bson_append_int( cond, "sessions.id",133333);
  bson_finish( cond );

  bson_init( op );
    bson_append_start_object( op, "$set" );
      bson_append_int( op, "sessions.$.setOID.Number",3333);
      bson_append_int( op, "sessions.$.custID.Number",4444);
      bson_append_int( op, "sessions.$.new_attr_1",0);
      bson_append_int( op, "sessions.$.new_attr_2",2);
    bson_append_finish_object( op );
  bson_finish( op );

  mongo_update( conn, "db.doc", cond, op, MONGO_UPDATE_BASIC );

  bson_destroy( cond );
  bson_destroy( op );
}