public IEnumerable <IPersonEntity> ListPeople(IPeopleFilter filter)
{
var people = new List <IPersonEntity>();
// For most databases this would be call to a Stored Procedure (or a View) with the SPROC handling the filtering
// and the age group.
// But here - particularly since we're allowing unfiltered lists - just do a simple
// SELECT * and do the filtering with LINQ.
var sql = " SELECT * FROM Person ";
var dt = ExecuteQuery(sql);
// Q: How would this happen without an exception?
// A: Someone changed the ExecuteQuery method
if (dt == null)
{
throw new Exception($"An empty dataset was returned from the query: {sql}");
}
foreach (DataRow row in dt.Rows)
{
var person = new PersonEntity();
person.ID = (int)((Int64)row["ID"]);
person.FirstName = row["FirstName"].ToString();
person.LastName = row["LastName"].ToString();
person.Age = (int)((Int64)row["Age"]);
person.AgeRange = _agegroup.Get(person.Age);
people.Add(person);
}
if (filter != null)
{
people = people.Where(p => (filter.FirstName == null || p.FirstName.StartsWith(filter.FirstName, StringComparison.CurrentCultureIgnoreCase)) &&
(filter.LastName == null || p.LastName.StartsWith(filter.LastName, StringComparison.CurrentCultureIgnoreCase)) &&
(filter.MinAge == null || filter.MinAge <= p.Age) &&
(filter.MaxAge == null || filter.MaxAge > p.Age)).ToList();
}
return(people);
}