array foreach error in express.js

Question

I want to generate dynamic search for my website. I am using req.query to get JS object after the query string is parsed. I was facing problem in foreach in variable name price. Url is : http://www.localhost:3000/listing?price=1&price=2&gender=men&gender=women

var arrayGet = req.query;
var query ={};

for (var k in arrayGet){
    if (arrayGet.hasOwnProperty(k)) {
        if(k =='gender'){
            var gender = arrayGet[k];
            query["gender"] = { "$in" : gender };

        }else if(k =='colour'){
            var colour = arrayGet[k];
            query["colour"] = { "$in" : colour };

        }else if(k =='price'){
            price = arrayGet[k];

            if(price.constructor !== Array){
                var price = JSON.parse("[" + price + "]");
            }
            console.log(price);
            query.$or = price.forEach(function (currentarray, i) {
                console.log('value: '+currentarray[i]);
                if(price[i] =='1'){
                    return {
                        'price': {'$gte': 0 , '$lte': 100}
                    }
                }else if(price[i] =='2'){
                    return {
                        'price': {'$gte': 100 , '$lte': 150}
                    }
                }else if(price[i] =='3'){
                    return {
                        'price': {'$gte': 150 , '$lte': 200}
                    }
                }else if(price[i] =='4'){
                    return {
                        'price': {'$gte': 200 , '$lte': 1000}
                    }
                }
            });

        }else if(k =='material'){
            var material = arrayGet[k];
            query["attributes.caseMaterial"] = { "$in" : material };
        }else if(k =='size'){
            var size = arrayGet[k];
            query["item"] = {$elemMatch: { 'size': { $regex: size, $options: "-i"}, 'stock' : "Available"}};
        }else if(k =='options'){
            var options = arrayGet[k];
            query["attributes.options"] = { "$in" : options };
        }
    }
}


console.log(query);

Product.find(query, function (err, results) {
    console.log(results);
});

The error message is:

[ '1', '2' ]

value: 1

value: undefined

{ '$or': undefined, gender: { '$in': [ 'men', 'women' ] } }

undefined

Answer 1

Why you get { '$or': undefined, ... }

You are doing this:

query.$or = price.forEach(...)

But as these docs say, forEach returns undefined . So, it's normal. You should use map instead. It will return a new array with both elements:

query.$or = price.map(...)

Why you get value: undefined

You are using a currentarray parameter, but that's not an array you get, it's the current price. So, in your example, currentarray[1] is equal to '2'[1] , which is undefined .

Possible solution

Your code would be simpler if written like this:

query.$or = price.map(function (currentPrice) {
    switch(currentPrice) {
        case '1': return {'price': {'$gte': 0 ,   '$lte': 100} };
        case '2': return {'price': {'$gte': 100 , '$lte': 150} };
        case '3': return {'price': {'$gte': 150 , '$lte': 200} };
        case '4': return {'price': {'$gte': 200 , '$lte': 1000}};
        default : return {};
    }
});