frxUserDataSet - is this just a virtual data set?

hsm

Am I correct in my understanding that the frxUserDataSet component cannot actually contain data itself but that it merely handles the navigation through another set of data held elsewhere (eg an array or list of some sort) and that is does this by providing the programmer with a virtual 'RecNo' that is incremented each time a record is displayed in the report.

So we always use the procedure Report.GetValue to obtain the actual data at position RecNo in the actual data?

(like in the demo PrintStringList)

procedure TForm1.frxReport1GetValue(const VarName: String; var Value: Variant);
begin
  if CompareText(VarName, 'element') = 0 then
    Value := sl[StringDS.RecNo];    <-------- here
end;

gpi

You may use dataset's OnFirst, OnNext, OnPrior, OnGetValue, OnCheckEOF events and get dataset like TfrxDBDataset

hsm

gpi wrote: »

You may use dataset's OnFirst, OnNext, OnPrior, OnGetValue, OnCheckEOF events and get dataset like TfrxDBDataset

Ok thank you. I did spend some time looking at the demos and I couldn't see where the UserDataSet got loaded or how RecNo ever got updated.
Now I realise it never does get loaded but sort of acts as a wrapper around any other data in order to present the data to frxReport using the same uniform interface that TfrxDBDataset presents.

A very clever idea now that I understand how it works!

Regards