I am passing blank('') value in search parameter, it display no record. I want, when i pass null or blank value it ignore that parameter from search query, and display record. My code is 

```
var _branchName = req.query.branchName;
var _personName = req.query.personName;
var _clientID = req.query.clientID;

var _searchQRY = [
    {
        branchName: { $regex: _branchName, $options: '-i' }
    },
    {
        personName: { $regex: _personName, $options: '-i' }
    },
    {
        "client._id": _clientID
    },
    {
        isDeleted: { $ne: true }
    }];

objModel.find({ $and: _searchQRY }, function (err, results) {
    res.json({ status: config.responseStatus, record: results })
});

```

In this i pass "\_clientID" is blank(''). At that time i want to ignore that parameter and search on remains parameter.