Programming Guide - Actian

How You Can Use Data Entry Error HandlersThe following is the complete code for the another_handlerproc procedure:procedure another_handlerproc(errorfield = entryfield;errorframe = frameexec;errormessage = varchar(2000) not null) =declarestr = varchar(100) not null;enddeclarebeginmessage 'Error in field' + errorfield.Name +HC_NEWLINE +errormessage;return EH_NEXT_HANDLER;end;Although this procedure uses the message statement to compose the errorinformation, the text of the message is written to the w4gl.log file rather thandisplayed in a pop-up frame. Statements that normally cause display of a popupframe (such as the message statement and the ConfirmPopup method)perform differently when executed from within a data entry error handler. Fora discussion of other restrictions, see Restrictions on Data Entry Error Handlers(see page 315).The following statement from the frame's initialize block establishes theanother_handlerproc procedure as its error handler:CurFrame.DataEntryErrorHandler =CurFrame.Scope.GetProcHandle(name ='another_handlerproc');Example—How Data Entry Error Handler Hierarchy WorksBecause this frame is called by the parent frame that defined the handlerprocprocedure, the following process occurs if a user enters an erroneous value inan entry field in the child frame:1. The another_handlerproc procedure is called and it writes the name of theerror-triggering field, as well as the standard error message, into the logfile or trace window.2. The handlerproc procedure is called (because the another_handlerprocprocedure returns EH_NEXT_HANDLER), and it does the following:• Beeps• Displays a pop-up message only if the data type of the error field isdate• Returns control to the child frame (because it returns EH_RESUME)314 Programming Guide