Problem with date NIL

General
1

Hi Group, I’m trying to display some date data on a table, some fields may be empty… so when it gets to the null date field, I get error. The problem is that I also have to format the date first … if I enter the data read directly in the ListBox with rows.Column(“DataInvoice”).DateTimeValue it works, but if I first format the data in the date variable DataPrimaScadenzaFormattata and insert this in the ListBox and I read a null field I get an error … how can I solve the problem ?

Dim DataPrimaScadenzaFormattata as new date
DataPrimaScadenzaFormattata=rows.Column(“Rata1”).DateTimeValue

ListBoxIngressi.AddRow(DataPrimaScadenzaFormattataShortDate) 'ERROR WITH VALUE=NIL

ListBoxIngressi.AddRow(rows.Column(“Rata1”).DateTimeValue) 'OK WITH VALUE = NIL

I need to display a formatted date

2

You can simply use a try catch
And if you got an error display a placeholder value

3

Excuse my ignorance, what do you mean? I know it’s due to NIL/NULL value in database field… now I would like to handle it but I don’t know how. If I insert the database field directly I have no problems and if there is no data value it does not insert anything, if instead I format by declaring a date variable, I have problems with the data variable which returns the error on NIL values

4

Try to format the date
since it’s nil you get an exception
in the catch use the placeholder value (empty, “N/D”)

5 
// This should work

Var dateFromDB As DateTime = rows.Column(“Rata1”).DateTimeValue

ListBoxIngressi.AddRow( If(dateFromDB Is Nil, "", dateFromDB.ToString(DateTime.FormatStyles.Short, DateTime.FormatStyles.None)) )
6

The following format is a bit easier to read:

// We assume that the Column "Rata1" is a Date or DateTime Column!

If rows.Column(“Rata1”).Value <> Nil Then

  Var dateFromDB As DateTime = rows.Column(“Rata1”).DateTimeValue
  ListBoxIngressi.AddRow dateFromDB.ToString(DateTime.FormatStyles.Short, DateTime.FormatStyles.None)

Else

  ListBoxIngressi.AddRow ""

End If

// The above Code is untested, written without the Xojo IDE.

First we make sure the Field contains a Value and is not NIL/NULL. Then we add the Date to the ListBox or we add an empty Field to the Listbox.

@Rick_Araujo: Your code is perfectly correct, but too compressed for a lesson. My opinion… :wink:

1 Like
7

Yep, my style usually don’t focus only on a lesson, sometimes around 3 at once, as I’m very oriented towards good memory use, good speed, and terse readable code. :laughing:

1 Like
8

Thanks Rick A
I tried the code and it’s perfect, I didn’t know you could nest so many instructions… great.

Sasha S
I also understood your code and it works, the problem is that I have other lines of code where this possibility repeats and I should insert too many conditions.

Thanks to both of you anyway, I learned something new today :slight_smile: See you next time.

2 Likes
9

I believe this is an opportunity to use an extension method to add functionality to the Database Column Class. Something like:

Public Function FormattedDate(Extends value As DatabaseColumn) As String
  If value.Value Is Nil Then
    Return ""
  End If
  
  Return value.DateTimeValue.ToString(DateTime.FormatStyles.Long, DateTime.FormatStyles.None)
  
End Function

Drop this into a module and you can then use:

FormatedDateListBoxIngressi.AddRow(rows.Column(“Rata1”).FormattedDate)

Everywhere you need a formatted date from a database column with Null columns being handled.

5 Likes
10

2 posts were split to a new topic: Nil date error