Existance of a block in SQL*FORMS 3.0

Summary of determining the existance of a block in SQL*Forms 3.0:

Situation:

We are writing screens that pop-up blocks on the screen based on user inout. We did not want to "Hard-code" the block names, so we decided to store the block name in a file called :CONTROL.FORM_BLOCK_NAME. The user enters data into field :CONTROL.FORM_BLOCK_NAME. If a block with a name matching the user data exists then, then go to that block. If the block does not exist, then go to a block called GENERAL.

Solution:

In our key navigation trigger we have the following:

      GO_BLOCK(NAME_IN(':CONTROL.FORM_BLOCK_NAME'));
      IF FORM_FAILURE THEN
          GO_BLOCK(NAME_IN(':CONTROL.FORM_BLOCK_NAME'));
      END IF;

where :CONTROL.FORM_BLOCK_NAME has data entered by the user. (That is could be a name of a block that does not exist in the form.)

On a form level ON-ERROR trigger:

      IF ERROR_CODE = 40104
          THEN :CONTROL.FORM_BLOCK_NAME := 'GENERAL';
      ELSE
          MESSAGE(ERROR_TYPE||'-'||TO_CHAR(ERROR_CODE)||': '||ERROR_TEXT);
          BELL;
      END IF;

Caveat:

If Oracle changes it's error codes, then we will need to change the ON-ERROR trigger.

Sure would be easier to have a packaged function called BLOCK_EXISTS which returns TRUE if the passed block name exists in the form, or FALSE if it does not exist. Then we could do:

  If BLOCK_EXISTS(NAME_IN(':CONTROL.FORM_BLOCK_NAME')) Then     GO_BLOCK(NAME_IN(':CONTROL.FORM_BLOCK_NAME'));   Else
    GO_BLOCK('GENERAL');
  End if;

We are working on a Procedure to emulate a BLOCK_EXISTS package function.

Thanks to everyone who responded with suggestions!!

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|  Michael A. Rife                    | Email:   MAR7363_at_TM0006.LERC.NASA.GOV  |

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