let filter = {};
if (selectedCandidate != "") {
    filter.put('candidate', selectedCandidate);
}
if (selectedEmployer != "") {
    filter.put('employer.id', selectedEmployer);
}
if (selectedStatus != "") {
    filter.put('status', selectedStatus);
}
if (startDate != "") {
    filter.put('created_at', {
        '$gte': new Date(startDate),
        '$lte': new Date(endDate),
    });
}