public IEnumerable <TResult> GetData <TResult>(Func <TSource, TResult> selector)
{
selector.ThrowIfNull(nameof(selector));
using (_engine.BeginReadFile(_dataFile.FullName))
{
// The engine is IEnumerable.
foreach (TResult item in _engine.Select(selector))
{
yield return(item);
}
}
}
/// <inheritdoc />
/// <remarks>File must contain "Thing Name" columns.</remarks>
public List <string> ReadFile(string filename)
{
// Use HashSet to avoid duplicated data which can produce errors in further work.
var result = new HashSet <string>();
var engine = new FileHelperAsyncEngine <InputFileData>();
using (engine.BeginReadFile(filename))
{
// The engine is IEnumerable.
result.UnionWith(engine.Select(data => data.thingName));
}
return(result.ToList());
}