Is it possible to return a static and/or a derived value to a TypedList?

What I want to do is something like:

select a, b, "a" as staticValue, case(a=1, "Y", "N") as derivedValue
from foo
where...

It doesn't matter whether the SQL is actually executed like that but I'd like a result set that has the extra columns staticValue and derivedValue. Is this possible?

No, not directly via the fields. You've to add the column to the typedlist after the fetch. For example: add a DataColumn to the TypedList.Columns collection (it's a datatable).

I've added the column in the varous places that are indicated by ' __LLBLGENPRO_USER_CODE_REGION_START... however I'm unclear how to base my added column/field on anything apart from a database column. Could you give me an example of a static and a dervied column to replace this:

_fields.DefineField(CustomerFieldIndex.Id, Me.AmountOfFields, "DealerType", "", AggregateFunction.None)

DealerType is a derived field based on the values of three other fields.

Thanks!

Don't add a DefineField . Do: typedList.Columns.Add(new DataColumn(...));

Otis wrote:

Don't add a DefineField . Do: typedList.Columns.Add(new DataColumn(...));

My second head slap for the morning... I've removed the DefineField and now have things working well if I explicitly reference my derived column/property however the derived value is not accessible to the datagrid (as far as I can tell). I think this has to do with the way the datagrid retrieves the column values but this is where my .NET knowledge runs out. Am I on the right track? Could you give me a pointer or two? I know this is sort of off-topic for LLBL Gen but any assistance is appreciated.

The column should be visible in the grid, as it's a normal datacolumn. You just added a datacolumn to the Columns collection and it doesn't show up? hmm... A datatable is bound using its DataView object, which in turn simply produces property descriptors for all datacolumns in its datatable, so it should turn up.

Otis wrote:

The column should be visible in the grid, as it's a normal datacolumn. You just added a datacolumn to the Columns collection and it doesn't show up? hmm... A datatable is bound using its DataView object, which in turn simply produces property descriptors for all datacolumns in its datatable, so it should turn up.

The _column _is available however the values in the columns are all false (it's a boolean) until I explicitly reference datatable.columnname at which time (I think) the property is accessed and the derived value calculated. Does this sound right or am I completely off track?

I've never used this feature, but it does sound kind of silly to me though, why calculate the value when it's first accessed?...

The answer, for those interested, is to add an expression to the column when adding the column to the table.

So

             _columnName = New DataColumn("Name", GetType(System.String), Nothing, MappingType.Element)

becomes

             _columnName = New DataColumn("Name", GetType(System.String), "LastName + ', ' + FirstName", MappingType.Element)

It seems odd to me to add it here but it works and who am I to argue with the way Microsoft does things...