How to use an external variable in MongoDB 'where' query via Javascript?

Question

I have a MongoDB query that searches all properties for a value defined in the search variable. It works the following way:

 db.collection.findOne({
                $where: function() {
                    var search = 'searchstring';
                    for (var key in this) {
                        if (this[key] === search) {
                          return true;
                        }
                        return false;
                    }
                }
            });

However, I would like to define the search variable outside the query.

But when I do so, I get an error that it is not referenced (i.e. scoping issue):

"ReferenceError: search is not defined near '[key] === search

How can I use or pass the variable to the query filter?

Answer 1

You can try something like this:

var searchstring = 'whatever';
var params = {};
params.$where = 'function() {' +
    'var search = "' + searchstring + '";' +
    'for (var key in this) {' +
        'if (this[key] === search) {' +
            'return true;' +
        '}' +
        'return false;' +
    '}' +
'}';
db.collection.findOne(params);

(Stringify your function and concat with external variable)

Worked for me via mongoose