NodeJS MongoDB Dynamic Query

Question

I have a NodeJS server running express with a get method at '/api/jobs/'. When called I get some querystring parameters from the url and they make a query against the MongoDB database to get jobs.

Example Url: '/api/jobs/?Groups=1,2&Statuses=3,4'

The MongoDB query i am trying to construct is this:

{ $or: [{"Group.Id" : 1}, {"Group.Id" : 2}], $or: [{"Status.Id": 3}, {"Status.Id": 4}]}

If I run this directly against the database I get the results I need but I can't think of way of constructing the query dynamically in JavaScript. Any attempt i've made gives me an object like this as the $or property can only exist once in a proper JSON object.

{$or : [{"Group.Id" : 1}, {"Group.Id" : 2}]}

Any ideas on how to do this either using JavaScript or thorugh the MongoDB Node API?

Answer 1

Firstly get the query properties, which will be strings:

const groupString = req.query.Groups; // === '1,2'
const statusString = req.query.Statuses; // === '3,4'

Split at the commas and parse as integers:

const groupNums = groupString.split(',').map(parseInt); // === [1, 2]
const statusNums = statusString.split(',').map(parseInt); // === [3, 4]

Then search for any of the group IDs. Your query should look like this:

const query = {"Group.Id": { $in: groupNums }, "Status.Id": { $in: statusNums } };

Do the same for the status IDs.

Answer 2

You can use this

app.get('/', function(req, res, next) {
var queryArry = [];
for (var i in req.query) {
    var sampleObject = { value: [] };
    sampleObject.name = i;
    req.query[i].split(',').forEach(function(each) {
        sampleObject.value.push(parseInt(each));
    })
    queryArry.push(sampleObject);
 }
  var mongoquery = {};

  for (var i in queryArry) {

     mongoquery[queryArry[i].name] = queryArry[i].value;

 }
  res.send(mongoquery);
 });

But in this case, you have to send same name field of MongoDB and query parameter key. If you did this it is fully dynamic query builder.