HP 3000 Manuals

HP ALLBASE/4GL Developer Self-Paced Training Guide

Input Field Processing 

HP ALLBASE/4GL performs input field processing for input fields after
display processing for the field has been completed.


            

   1.  When HP ALLBASE/4GL first enters this processing sub-system, it
       places the cursor in the current field and waits for user input.
       This is the only time that HP ALLBASE/4GL accepts any form of user
       input, including function keys or cursor movement requests.

       A field commit action indicates that data entry for the field is
       complete.  Some actions that constitute a field commit are:

          *   Moving the cursor off the field by:

                 *   Pressing Return,

                 *   Pressing Tab or Shift + Tab followed by Return,

                 *   Moving the cursor to another field by pressing
                     cursor up cursor down or cursor home followed by
                     Return.

          *   Pressing the  Commit Data  function key.

       _________________________________________________________________ 

       NOTE  In general, pressing a function key other than  Commit Data  
             does not initiate a field commit.

       _________________________________________________________________ 

       There are only two cases in which a field commit occurs as a
       result of pressing a function key:

          *   If the action behind the key initiates a commit data
              action, or

          *   If the action is a function which moves a new value to
              *FIELDNO, a field commit occurs on return to the screen
              field.

       Once HP ALLBASE/4GL accepts the field commit, the remainder of the
       input field processing is executed.

   2.  HP ALLBASE/4GL determines if the field commit is a new commit
       action for this field.  A new field commit is recognized for the
       following situations:

          *   The data in the screen field has altered since the last
              commit action for the field.

          *   A different numbered input field has been processed since
              this field was last committed.

   3.  If the field commit is not a new commit action, HP ALLBASE/4GL
       checks to see if an error was generated by the previous commit
       action.  If an error was generated on the previous commit, this
       commit action is accepted.  Otherwise input processing for the
       field is terminated.

   4.  The data input in the screen field is accepted into the screen
       buffer.

   5.  HP ALLBASE/4GL now validates the screen field buffer contents.
       Firstly, the following automatic system tests are performed:

          *   Field Requirements.  Validation fails under the following
              circumstances:

                 *   The field is blank and it is defined as a required
                     field,

                 *   Less than the defined minimum number of characters
                     for the field have been entered.

          *   Data Type Requirements.  HP ALLBASE/4GL performs the
              following data type validation:

                 *   Correct data type for edit code,

                 *   If a date field, validate the date format,

                 *   If numeric, validate number of decimal places,

                 *   If signed numeric, validate sign.

       If any of these criteria are not met, HP ALLBASE/4GL generates an
       error signal, displays a standard system error message, and
       terminates the validation.

       If the input field data passes the system validation tests, any
       developer specified validation tests (if specified) are applied.
       These tests are as follows:

          *   Value within a specified range.

          *   Value in a specified table.

       If either of these tests fail, HP ALLBASE/4GL displays the
       developer defined message assigned to the range or table.  If
       there is no message associated with the range or table, HP
       ALLBASE/4GL displays a default system error message.

       Error messages are one of five different types of messages.  They
       are the most important type of message in terms of their effect on
       input field processing logic.  They provide an automatic means of
       ensuring that the user enters valid data in a field.  You will
       define a number of messages in later lessons.

   6.  If the validation tests of the screen field data initiate an error
       message, processing returns to step 1 and the user must re-enter
       the field data.

   7.  When the field data has been accepted and validated, the switch
       *ENTERED is set on.  This allows you to determine whether the
       function is being performed prior to, or after, data entry for the
       field.

   8.  The function, if specified as an after function, or as both a
       prior and after function, is executed.

   9.  The function, through its processing, may initiate an error
       message.  If so, processing branches to step 11.

  10.  HP ALLBASE/4GL now performs the automatic data movement for the
       field.  The contents of the screen buffer are moved to the primary
       data movement field, and the other data movement fields.
       Processing of the field is complete.

  11.  If the after function generates an error message, HP ALLBASE/4GL
       tests the value in the *FIELDNO communication area field.  If this
       value has not been modified by the function, processing returns to
       the beginning of the field (Step 1).  However, if the function has
       modified the value in *FIELDNO, HP ALLBASE/4GL restores the
       contents of the field to the condition that existed at the start
       of the input processing, and then terminates processing of the
       field.

MPE/iX 5.0 Documentation