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foxpro error handling

Posted on 2013-11-12
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Last Modified: 2013-11-20
I'm currently using the Microsoft.XMLHTTP object to access websites within my program (scan through a table with URLs).
The problem is that with my current error handler, which is a simple try/catch statement, ends when an error occurs. Is there a way with error handling to continue the code, or go to the next row of a scanned table when an error occurs, rather than ending the program?
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Question by:esak2000
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pcelba earned 500 total points
ID: 39643855
Well...  TRY CATCH continues the code execution after the ENDTRY command so if you enclose a smaller part of code into TRY-CATCH then you may achieve what you need.

Another option is to use Error event in your class. If you define Error event then it is fired when an error occurs and then the control returns to the next line of your code.

And finally ON ERROR also offers the option to continue. RETURN command in your error procedure continues after the line which caused the error.
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Author Closing Comment

by:esak2000
ID: 39643856
Thank you for the super quick response. Exactly what I needed.
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Author Comment

by:esak2000
ID: 39643858
Just one follow up question, can I add a "loop" statement in the "catch"?
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Expert Comment

by:pcelba
ID: 39643908
No, this is not allowed (it will generate error 2059) but you may set some variable and issue the LOOP based on this variable:
FOR i = 1 TO 5
TRY
llCatch = .F.
aa = bb
CATCH
? i
llCatch = .T.
ENDTRY
IF m.llCatch
  LOOP
ENDIF
? "No LOOP"
NEXT

Open in new window

"No LOOP" should not appear.
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Author Comment

by:esak2000
ID: 39644464
Perfect, thank you!
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Expert Comment

by:Olaf Doschke
ID: 39661732
Well, to pull it together (though this already is solved):

If you do something like
Try
   Scan
     oBrowser.navigate2(url)
   Endscan
Catch
  * ...
Endtry

Open in new window

Then the first error makes VFP leave the code in the try block and not return there. Try Catch is not meant for overall error handling, but for catching local errors, so the solution simply is to put it inside the loop.

 
Scan
   Try
       oBrowser.navigate2(url)   
   Catch
     * log url as temporary or permanently not working
   Endtry
Endscan

Open in new window


There is no need to put a loop or the LOOP command for continuation of a loop into the try..catch, neither in the try, nor in the catch block. There also is no need for Pavels construct to set a variable llCatch, then. If you put try catch inside the loop you come out of it before the endscan and therefor loop and try with the next record again, this is what you intended, isn't it? Then simply do so :)

Edit: There is no wrong or right here, about where to put the try or the loop. It depends on your intention. If you want to continue trying further records, put the try inside the loop to continue with further records. If you want to stop processing data, when the first error happens, then put the loop inside the try..catch. Still you are free to do what you want :)

Bye, Olaf.
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