NULL time in TwwGridColumn is displayed as 0:00

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Harald Lampke

• November 20, 2023 11:13
• Edited

I've got a SQLite database with a column which contains time values (no date!). Because SQLite does not have special date-time-data types, the data type of the row is REAL. The values are in the range from 0.0 (0:00:00) up to 0.9999... (23:59:59), or NULL for "no time".

To display the time column in a TwwDataGrid, I use a TwwGridColumn with ControlType = gdctDateTime and ControlAttributes.DateTime.DataType = wwDTEdtTime. The problem is, that NULL values are displayed as "0:00" instead of showing a blank cell.

On the contrary, colums with a date value and ControlAttributes.DateTime.DataType set to wwDTEdtDate are working fine with NULL values.

Additional information:

• The DataSource is bound with a TBindSourceDB to a TFDQuery.
• I can guarantee that the NULL values are really NULL, not just empty strings or zero.
• I have NOT tested with an other database type (Interbase, FireBird, ...), so I don't know if the problem only occures when the database time field is a floating point type instead of a "real" date-time-type.

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  Michael Verhagen

  • November 20, 2023 16:21

  I have run into various problems with displaying things in grids, from it showing "(memo)" instead of the beginning of a string, to things such as you described.

  In recent FMX apps that use SQLite, I remember having to do some kind of casting in the queries to get around such problems but I will have to dig around for that and I hope to post a follow-up message here in the next day or two.  I will also look to see if I specify anything special for those columns in the grids.

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