filter mongodb object result by ObjectId with Underscore

Sadly mongodb ObjectId instances do not work properly with JavaScript's equality operators == or ===. You either need to use the provided method: objectId1.equals(objectId2) or ensure they are both converted to strings and then underscore or === will work.

platformInfo = _.filter(user.platforms, function (platform) {  return platform.pId.toString() === platformId;})

I tried to write a general function for that problem using underscore.js:

function findWhereObjectId(objs, comp) {    return _.find(objs, function(obj) {        return _.some(_.keys(obj), function(key) {            return (key == _.keys(comp)[0] && obj[key].equals(comp[key]));        });    });};

You could now call findWhereObjectId(user.platforms, {"pId": platformId}) and it should give you the first match.

As mentioned before, mongodb ObjectId instances do not work properly with JavaScript's equality operators.However, there's another simpler solution for this problem: You could take your MongoDB result object and convert it to a string via JSON.stringify():

    var myString = JSON.stringify(MONGODB_RESULT);

After that you can convert that string back to an object via JSON.parse():

    var myObject = JSON.parse(myString);

You can now perform any Lodash/Underscore operation on that object.

Hope that helps!