Question on reading DateTime strings

[champlin2]

When reading a field that is specified as a DateTime if the CSV only contains a date the time portion is set to midnight (00:00:00). Is there any way to tell if the CSV just contained the date portion (and the time was set to midnight automatically on reading) or if the CSV actually contained a time portion of 00:00:00?

[JoshClose]

Where would you be looking at the data? You could create an extra property like ContainsTime and set that based on the value of that field. You'd do that either through a type converter, or in a mapping using the Convert map method.

[champlin2]

@JoshClose

Ok tried doing this by creating a custom converter to determine if the date had a time portion or if it was just a date and the time was assumed to be midnight. That is all working. Then I added a public bool member and a public method to set the value or the member to true and then passed this as an Action to the custom converter constructor. It calls back the Action when it detects that the time portion was not set correctly and sets the public member but later on when I access the public member of the class its false - like it gets lost after the converter sets it. Any ideas?

public sealed class TestClass : ClassMap<TestClass>
{
  public TestClass()
  {
    ...
    Map(m => m.EndDate).Name("EndDate").TypeConverter(new CustomEndDateConverter(EndDateWasIncremented));
    ...
  }

  ...
  public DateTime? EndDate {get; set;}
  ...
  public bool EndDateIncremented {get; set;}
  ...
  public void EndDateWasIncremented() { EndDateIncremented = true; }
}

public class CustomEndDateConverter : DateTimeConverter
{
  private readonly Action _endDateIncrementedAction;

  public CustomEndDateConverter(Action endDateIncrementedAction)
  {
    _endDateIncrementedAction = endDateIncrementedAction;
  }

  public override object ConvertFromString(string text, IReaderRow row, MemberMapData memberMapData)
  {
    // If no time portion entered
    _endDateIncrementedAction?.Invoke();
  }
}

[JoshClose]

I'm not sure how that compiles as ConvertFromString needs to have an object returned from it.

Here is an example.

void Main()
{
    var s = new StringBuilder();
    s.Append($"Id,Name,EndDate\r\n");
    s.Append($"1,one,{new DateTime(2021, 4, 13)}\r\n");
    var config = new CsvConfiguration(CultureInfo.InvariantCulture)
    {
    };
    using (var reader = new StringReader(s.ToString()))
    using (var csv = new CsvReader(reader, config))
    {
        csv.Context.RegisterClassMap<FooMap>();
        csv.GetRecords<Foo>().ToList().Dump();
    }
}

private class Foo
{
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime? EndDate { get; set; }
    public bool IsEndDateMidnight { get; set; }
}

private class FooMap : ClassMap<Foo>
{
    public FooMap()
    {
        Map(m => m.Id);
        Map(m => m.Name);
        Map(m => m.EndDate);
        Map(m => m.IsEndDateMidnight).Convert(args =>
        {
           var endDate = args.Row.GetField<DateTime?>(nameof(Foo.EndDate));
           if (endDate == null)
           {
               return false;
           }
           
           return endDate.Value.Hour == 0 && endDate.Value.Minute == 0 && endDate.Value.Second == 0 && endDate.Value.Millisecond == 0;
        });
    }
}

[champlin2]

@JoshClose

Tried using the ".Convert" option instead of TypeConverter (and add a method to the custom converter to see if we incremented the date) but not sure what to pass to the ConvertFromString method:

        Map(m => m.EndDate).Name("EndDate").Convert(args =>
        {
            var endDateConverter = new CustomEndDateConverter();
            var endDate = endDateConverter.ConvertFromString( ??, ??, ??);
            _endDateIncremented = endDateConverter.EndDateWasIncremented();
            return (DateTime?)endDate;
        });

[JoshClose]

If you want to use a customer converter, just do

Map(m => m.EndDate).Name("EndDate").TypeConverter<CustomEndDateConverter>();

[champlin2]

@JoshClose

I tried that (see above) but as I described when I called the callback to set the property in the TestClass it doesn't stick after calling GetRecords<>

[JoshClose]

I'm confused. You're setting a value on the mapping?

[champlin2]

@JoshClose what I'm trying to do is when the value is converted from a string in the CSV file to be able to tell if the CSV contained 00:00:00 for the time portion of the DateTime or if no time portion was entered and 00:00;00 was assumed. Later on when I'm iterating over the list of objects that is returned from GetRecords I want to know which had midnight set and which it was assumed for so I'm trying to set a member in that TestClass to let me know which of the two it was.