Spring Mongodb query for Employee first and last name and dob using range criteria - spring

Question

I have some data on employees which stores typical information like first and last name and dob, etc... The business case I have been given requires me to pull a record for an employee based on a criteria of first name, last name and dob.
At first I thought this would be easy, but after doing a search in db, I found the dob records have differing timestamps (which doesn't make sense). Without getting into the internal company issues of addressing this, I need my query to look at a dob with a start of day and end of day range.
My sample code below demonstrates my latest effort to solve this issue but have not been able to match results with what i see in the db. This code is using Spring Mongodb Query and mongoDbTemplate for constructing the queries. I could really use some help in figuring this one out.
I have to set a date range to ensure I get the employee for that day but can't figure out how to construct the query correctly.
sample method:
#Slf4j
#Repository
public class EmployeeDao {
private static final int START_OF_DAY = 0;
private static final int END_OF_DAY = 1;
#Getter private MongoTemplate mongoTemplate;
#Autowired
public void setMongoTemplate(MongoTemplate mongoTemplate) {
DB db = mongoTemplate.getDb();
mongoTemplate = new MongoTemplate(db.getMongo(), "EmployeeDB");
this.mongoTemplate = mongoTemplate;
}
public List<Employee> findEmployeeByNameIdDobRange(String lName, String fName, Date dob){
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
String startFmt = df.format(convertTo(dob, START_OF_DAY));
String endFmt = df.format(convertTo(dob, END_OF_DAY));
Query q = new Query();
q.addCriteria(Criteria.where("employee.firstName").regex(fName, "i")
.and("employee.lastName").regex(lName, "i")
.andOperator(
Criteria.where("employee.dob").gte(startFmt).lte(endFmt)
)
);
return return getMongoTemplate().find(q, Employee.class);
}
private Date convertTo(Date dt, int startOrEnd){
Calendar cal = Calendar.getInstance();
cal.setTime(dt);
switch (startOrEnd) {
case END_OF_DAY:
cal.set(Calendar.HOUR_OF_DAY, 23);
cal.set(Calendar.MINUTE, 59);
cal.set(Calendar.SECOND, 59);
cal.set(Calendar.MILLISECOND, 999);
break;
case START_OF_DAY:
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 1);
cal.set(Calendar.SECOND, 1);
cal.set(Calendar.MILLISECOND, 1);
break;
default:
throw new IllegalArgumentException("starOrEnd paramter does not equal 0 for beggining or 1 for end of day");
}
log.info(cal.toString());
return cal.getTime();
}
I appreciate any suggestions that can be made. Thanks!