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Powerbuilder Datawindow "Expression is not valid" cannot be intercepted

When I try to evaluate an expression with describe, it is not possible to catch it in case of an error. For example, in the following code, if the column does not exist, a window with "Expression is not valid" is displayed. I would have expected that an exception would be thrown. try dw.describe("evaluate('columname',1)") catch (DWRuntimeError dwrte) logger.log(dwrte.text) end try

Solution

  • This post doesn't contain any questions so I hope this response is not out of this world.

    Evaluate function used in describe method returns "!" if an error occurs, but it does NOT contain any additional information what the error is, so as far as I am aware you can't intercept (what you described) in the try...catch block.

    What you could possible do is temporarily disable user prompt thus no error messages would pop up to the user and replace try...catch block with if...else block, for example:

    string ls_ret, ls_userprompt    

ls_userprompt = dw.describe("DataWindow.NoUserPrompt")

// user won't see any (error) messages
dw.modify("DataWindow.NoUserPrompt='Yes'")

ls_ret = dw.describe("evaluate('cc_auftlos', if(auftlos_verg=1, 1, 0))")

if ls_ret = "!" then
    // evaluate not correct
    logger.log("Error text defined by you")
else
    // evaluate OK, do some processing with the result
end if

dw.modify("DataWindow.NoUserPrompt='" + ls_userprompt + "'")

    Hope this somewhat helps you.