Question about fpreport

[ginoo]

I ran some tests and found that the OnBeforePrint event is misaligned with the dataset it refers to. For example,

OnBeforePrint
I read the value of HotelDataSet -> ID and write it to a memo; the value is printed in the next step.

Now the question: if I want to read a value from HotelDataSet and change a color based on it, how should I do it?

Thank you

[Graeme]

See the `rptexpressions.pp` demo included with fcl-report (part of FPC's source code). It's the expression evaluator demo report.

[ginoo]

Thanks @Graeme for reporting it. I looked at the example and I'm looking at it again now, but I don't think it helps, so I'll explain why.
In the OnBeforePrint event, whether I use values ​​from a dataset or a variable, they're assigned to the next line.

To illustrate with the example you provided, in `rptexpressions.pp` after the first TExpressionsDemo.DoBeforePrint, the value of rpt.Variables.FindVariable('isEven').AsBoolean is "false," but the first line of the report displays "true." This is because, as mentioned above, the next line is displayed.

Another problem is that zeos calculated fields don't work; I didn't recognize them.

[ginoo]

I'm no expert, but at first glance, an event should be added to
the TFPReportLayouter.ShowDetailBands procedure; on line 11986.