var patientObj = JSON.parse(JSON.stringify(patients));

for (var i = 0; i < patientObj.length; i++) {
var patientIds = "00" + (i + 1);
var patientNewIdObj = { barCodeId: patientIds}
var currentPatientId = patientObj[i]._id;

modelPatient.findOneAndUpdate({ _id: currentPatientId }, patientNewIdObj, 
{ new: true, safe: true }).exec(function (err, patientRet) {
    if (err) {
        callBack(callBackResponse.callbackWithDefaultError(err));
    }
    else if (patientRet == null || patientRet == undefined) {
        callBack(callBackResponse.callbackWithfalseMessage('Invalid 
        patient ID'));
    } else {
        callBack(callBackResponse.callbackWithData(patientRet));
    }
});
}