Forum Discussion

marinb's avatar
marinb
Contributor
9 years ago

Object property does not exist right after it passes an exist check?

Given the following piece of code in our script:   Sys.Refresh(); if (aqObject.IsSupported(Sys.Desktop.ActiveWindow(), "MappedName")) { if (Sys.Desktop.ActiveWindow().MappedName != null) //FA...
  • ghuff2's avatar
    ghuff2
    9 years ago

    Well the only place I can think the issue would be is when calling the ActiveWindow() method. You aren't technically checking the same object since you are grabbing a new object with each call to the ActiveWindow() method. That method returns either a Window object or an empty stub object if no top-level window is found. In your code it must return a Window object in the first check then during the second check for whatever reason something changed and TestComplete doesn't think there's any top-level windows so it returns an empty stub object which doesn't have the MappedName property.

     

    I couldn't reproduce the issue myself, but my suggestion is that you return the results for the ActiveWindow() method into a variable, then reference that same variable. So I'd change your code to this:

     

    Sys.Refresh();
activeWindow = Sys.Desktop.ActiveWindow()
if (aqObject.IsSupported(activeWindow, "MappedName"))
{
    if (activeWindow.MappedName != '')  //FAILS HERE
    {
       <...snip...>

    Which BTW, the MappedName property is never null. If you don't have a MappedName for an object it returns an empty string which is different than null.

     

marinb's avatar
marinb
Contributor

True, our application can also be quite unresponsive. I try to make it as robust as possible, but you still get dirty loops like this in order to prevent hiccups... if x.exists, then if  x really exists, then if y exists, but really, x should exist! etc etc ;-)

 

     for (var i = 0; i < iMaxWait; i++)
     {
        if (oMapping.Exists)
        {
            if (aqObject.IsSupported(oMapping, "VisibleOnScreen"))
            {
                if (oMapping.Exists)
                {
                    if (oMapping.VisibleOnScreen)
                    {
                        if (oMapping.Enabled || bDoNotCheckOnEnabled)
                        {
                            bFound = true;
                            break;
                        }
                    }
                }
            }
        }
        <snip>

 

If I remove the second exists check, it fails occasionally. With that extra check, it does not.

If I remove the VisibleOnScreen supported action, it fails occasionally, even while every object always should have it.

 

Manfred_F's avatar
Manfred_F
Regular Contributor
9 years ago

Yes, You Need all kinds of caution.

 

I use the following pattern, see attachment:

 

  • disable error handling
  • try several times
    • execute the steps
    • on success leave Loop,
    • on error
      • reset error
      • wait a Moment
      • stay in Loop
  • enable error handling

 

This allows me to use rather straight-Forward code..