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DISPLAY statement

Moves data to a screen buffer and displays the data on the screen or other output destination. The AVM uses frames to display data. A frame describes how constant and variable data is arranged for display and data entry. You can let ABL construct default frames or you can explicitly describe frames and their characteristics.

Data movement



Syntax

DISPLAY
  {[ STREAM stream | STREAM-HANDLE handle ] [ UNLESS-HIDDEN ] }
[      { expression
              [ format-phrase ]
              [ ( aggregate-phrase ) ]
              [ WHEN expression ]
              [ @base-field ]
         }
     | [ SPACE [ ( n ) ] ]
     |[ SKIP [ ( n ) ] ]
] ...
{ [ IN WINDOW window ] [ frame-phrase ] [ NO-ERROR ] }
 
DISPLAY
  { [ STREAM stream | STREAM-HANDLE handle ] [ UNLESS-HIDDEN ] }
      record [ EXCEPT field ... ]
  { [ IN WINDOW window ] [ frame-phrase ] [ NO-ERROR ] }
 
DISPLAY
 {   expression ...
    | record [ EXCEPT field ... ]
 } 
  WITH BROWSE browse [ NO-ERROR ]
STREAM stream
Specifies the name of a stream. If you do not name a stream, the AVM uses the unnamed stream. See the DEFINE STREAM statement reference entry and the chapter on alternate I/O sources in OpenEdge Development: Programming Interfaces for more information on streams.
STREAM-HANDLE handle
Specifies the handle to a stream. If handle is not a valid handle to a stream, the AVM generates a run-time error. Note that stream handles are not valid for the unnamed streams. See the chapter on alternate I/O sources in OpenEdge Development: Programming Interfaces for more information on streams and stream handles.
UNLESS-HIDDEN
Restricts DISPLAY to fields whose HIDDEN attribute is FALSE.
expression
Identifies a constant, field name, variable name, or expression that results in the value you want to display. This can also be the built-in field name, proc-text, that returns a character string of column values from a row returned by a stored procedure proc-text-buffer.

If expression is a simple field or variable, the AVM checks to see if that particular field or variable is used previously in the same frame. If it has, the AVM displays the field or variable in the same frame field as the earlier instance of that field or variable.

In array fields, array elements with constant subscripts are treated just as any other field. Array fields with no subscripts are expanded as though you had typed in the implicit elements.

Note: You cannot display elements of an unfixed indeterminate array parameter or variable. You can use the EXTENT statement to fix the number of elements in the array before displaying them. For more information, see the EXTENT statement reference entry.

If you reference a[i] in the same frame that you reference a or a[constant], a[i] overlays the appropriate frame field based on the value of i. It is displayed in a new frame field for a[i]. For example.

r-arry.p

/*1*/ DEFINE VARIABLE ix AS INTEGER NO-UNDO.

/*2*/ FOR EACH SalesRep:
/*3*/   DISPLAY SalesRep.SalesRep SalesRep.Region SalesRep.MonthQuota.
/*4*/   DO ix = 1 TO 12:
/*5*/     SET SalesRep.MonthQuota[ix] WITH 1 COLUMN.
/*6*/   END.
/*7*/   DISPLAY SalesRep.MonthQuota 
/*8*/     WITH FRAME a COLUMN 40 ROW 3 1 COLUMN.
/*9*/ END.

Here, month-quota[i] is referenced in the same frame that month-quota is referenced. That is, line 5 references month-quota[i] and line 3 references month-quota. Both references use the same frame. Therefore, instead of creating a new frame field for month-quota[i], the AVM uses the same frame fields created for the entire month-quota array.

In the next procedure, line 4 references only elements 1 and 2. Therefore, when the AVM tries to overlay month-quota[i] in line 6, there is only room for elements 1 and 2. The AVM returns an error after you enter data for those two elements.

r-arry2.p

/*1*/ DEFINE VARIABLE ix AS INTEGER NO-UNDO.

/*2*/ FOR EACH SalesRep:
/*3*/   DISPLAY SalesRep.SalesRep SalesRep.Region 
/*4*/     SalesRep.MonthQuota[1] SalesRep.MonthQuota[2].
/*5*/   DO ix = 1 TO 12:
/*6*/     SET month-quota[ix] WITH 1 COLUMN.
/*7*/   END.
/*8*/   DISPLAY month-quota WITH FRAME a COLUMN 40 ROW 3 1 COLUMN.
/*9*/ END.

The following example shows a solution to that problem:

r-arry3.p

/*1*/ DEFINE VARIABLE ix AS INTEGER NO-UNDO.

/*2*/ FOR EACH SalesRep:
/*3*/   DISPLAY SalesRep.SalesRep SalesRep.Region
/*4*/     SalesRep.MonthQuota[1] SalesRep.MonthQuota[2] WITH 6 DOWN.
/*5*/   FORM ix SalesRep.MonthQuota[ix].
/*6*/   DO ix = 1 TO 12:
/*7*/     DISPLAY ix NO-LABEL.
/*8*/     SET SalesRep.MonthQuota[ix].
/*9*/   END.
/*10*/  DISPLAY month-quota WITH FRAME a COLUMN 40 ROW 3 1 COLUMN.
/*11*/ END.

If you explicitly reference a[ix] in a FORM statement, regular array fields (month-quota[1] and month-quota[2] in this example) are not overlaid.

format-phrase
Specifies one or more frame attributes for a field, variable, or expression. For more information on format-phrase, see the Format phrase reference entry.
aggregate-phrase
Identifies one or more aggregate values to be calculated optionally based on a change in a break group. This is the syntax for aggregate-phrase: 
{   AVERAGE
  | COUNT
  | MAXIMUM
  | MINIMUM
  | TOTAL
  | SUB-AVERAGE
  | SUB-COUNT
  | SUB-MAXIMUM
  | SUB-MINIMUM
  | SUB-TOTAL
} ... [ LABEL aggr-label ] [ BY break-group ] ...

For more information on aggregate-phrase, see the Aggregate phrase reference entry.

WHEN expression
Displays an item only when the expression used in the WHEN option has a value of TRUE. Here, expression is a field name, variable name, or expression whose value is logical.
@ base-field
The base-field must be the name of a field or variable; it cannot be an expression or constant. The field or variable must be viewed as a fill-in or text widget on the display.

The AVM reserves enough space for the base-field to hold the longest format displayed there. All right-justified fields (numerics that do not use side labels) are right justified within the reserved area. The label is left or right justified according to the base-field. Whenever you enter data into the base-field, the AVM blanks out any characters to the left or right of the area used by the field being displayed.

The AVM underlines a screen area that is the longer of the base-field and the overlaying field. However, you can enter as many characters as there are spaces in the format of the field.

To determine the format to use for displaying the expression at the base-field, the AVM looks at the following and uses the first format that applies:

  • An explicit Format phrase used with the expression.
  • If the expression is a character string constant, a format that accommodates that string.
  • If the data type of the expression matches that of the base-field, the format of the base-field.
  • The standard format of the expression as if it were displayed without a base-field.
SPACE [ ( n ) ]
Identifies the number (n) of blank spaces the AVM inserts after the displayed expression displays. The n can be 0. If the number of spaces is more than the spaces left on the current line of the frame, the AVM starts a new line and discards extra spaces. If you do not use this option or do not use n, the AVM inserts one space between items in the frame.
SKIP [ ( n ) ]
Identifies the number (n) of blank lines the AVM needs to insert after the expression is displayed. The n can be 0. If you do not use this option, the AVM does not skip a line between expressions unless the expressions do not fit on one line. If you use the SKIP option but do not specify n, or if n is 0, the AVM starts a new line unless it is already at the beginning of a new line.
IN WINDOW window
Identifies the window where the expression is displayed. The expression window must evaluate to the handle of a window.
frame-phrase
Specifies the overall layout and processing properties of a frame. For more information on frame-phrase, see the Frame phrase reference entry.
record
Identifies the name of the record you want to display. Naming a record is shorthand for listing each field individually. This can also be the built-in buffer name, proc-text-buffer, that returns each row retrieved by a stored procedure.

To display a record in a table defined for multiple databases, you must qualify the record's table name with the database name. See the Record phrase reference entry for more information.

EXCEPT field . . .
Indicates that the AVM displays all fields except those fields listed in the EXCEPT phrase.
WITH BROWSE browse
Indicates that the AVM displays the values into the current row of the specified browse widget.
Note: DISPLAY . . . WITH BROWSE cannot be used with a dynamic browse. Instead, the user must set the browse column's SCREEN-VALUE attributes.
NO-ERROR
Suppresses ABL errors or error messages that would otherwise occur and diverts them to the ERROR-STATUS system handle. If an error occurs, the action of the statement is not done and execution continues with the next statement. If the statement fails, any persistent side-effects of the statement are backed out. If the statement includes an expression that contains other executable elements, like methods, the work performed by these elements may or may not be done, depending on the order the AVM resolves the expression elements and the occurrence of the error.

As an exception to the general rule, the DISPLAY statement may continue to execute even if it encounters an error resolving some part of an expression. This attempt to complete the operation may result in displaying the empty string at the location of the intended output.

To check for errors after a statement that uses the NO-ERROR option:

  • Check the ERROR-STATUS:ERROR attribute to see if the AVM raised the ERROR condition.
  • Check if the ERROR-STATUS:NUM-MESSAGES attribute is greater than zero to see if the AVM generated error messages. ABL handle methods used in a block without a CATCH end block treat errors as warnings and do not raise ERROR, do not set the ERROR-STATUS:ERROR attribute, but do add messages to the ERROR-STATUS system handle. Therefore, this test is the better test for code using handle methods without CATCH end blocks. ABL handle methods used in a block with a CATCH end block raise ERROR and add messages to the error object generated by the AVM. In this case, the AVM does not update the ERROR-STATUS system handle.
  • Use ERROR-STATUS:GET-MESSAGE( message-num ) to retrieve a particular message, where message-num is 1 for the first message.

If the statement does not include the NO-ERROR option, you can use a CATCH end block to handle errors raised by the statement.

Some other important usage notes on the NO-ERROR option:

  • NO-ERROR does not suppress errors that raise the STOP or QUIT condition.
  • A CATCH statement, which introduces a CATCH end block, is analogous to a NO-ERROR option in that it also suppresses errors, but it does so for an entire block of code. It is different in that the error messages are contained in a class-based error object (generated by the AVM or explicitly thrown), as opposed to the ERROR-STATUS system handle. Also, if errors raised in the block are not handled by a compatible CATCH block, ON ERROR phrase, or UNDO statement, then the error is not suppressed, but handled with the default error processing for that block type.
  • When a statement contains the NO-ERROR option and resides in a block with a CATCH end block, the NO-ERROR option takes precedence over the CATCH block. That is, an error raised on the statement with the NO-ERROR option will not be handled by a compatible CATCH end block. The error is redirected to the ERROR-STATUS system handle as normal.
  • If an error object is thrown to a statement that includes the NO-ERROR option, then the information and messages in the error object will be used to set the ERROR-STATUS system handle. This interoperability feature is important for those integrating code that uses the traditional NO-ERROR technique with the newer, structured error handling that features error objects and CATCH end blocks.

Example

This procedure generates a hierarchical report of Customers (sorted by state and name), the orders belonging to those Customers, and the order-lines belonging to each order:

r-disp.p 

FOR EACH Customer NO-LOCK BY Customer.State BY Customer.Name:
  DISPLAY Customer.State Customer.CustNum Customer.Name.
  FOR EACH Order OF Customer NO-LOCK:
    DISPLAY Order.OrderNum Order.Name Order.ShipDate Order.PromiseDate.
    FOR EACH OrderLine OF Order NO-LOCK, Item OF OrderLine NO-LOCK:
      DISPLAY OrderLine.LineNum Item.ItemName OrderLine.Qty
        OrderLline.price.
    END.
  END.
END.

This procedure lists each order, Customer information, and the OrderLines for each Order. The procedure calculates an Order-value for each of the OrderLines of an Order, and adds those values to produce a total value for an entire Order.

r-disp2.p 

FOR EACH Order NO-LOCK, Customer OF Order NO-LOCK:
  DISPLAY Order.OrderNum Customer.Name Order.ShipDate Order.PromiseDate.
  FOR EACH OrderLine OF Order NO-LOCK, Item OF OrderLine NO-UNDO:
    DISPLAY OrderLine.LineNum Item.ItemName OrderLine.Qty OrderLine.Price
      OrderLine.Qty * OrderLine.Price (TOTAL) LABEL "Order-value".
  END.
END.

The r-disp3.p procedure displays a name and address list in a mailing label. The SKIP and FORMAT options are used to produce a standard address format. The WHEN option suppresses the display of the PostalCode field if there is no postal code value in the field.

r-disp3.p 

FOR EACH Customer NO-LOCK:
  DISPLAY Customer.Name SKIP Customer.Address SKIP Customer.Address2 SKIP
    Customer.City + ", " + Customer.State FORMAT "x(16)"
    Customer.PostalCode WHEN Customer.PostalCode NE "" SKIP(2)
    WITH NO-BOX NO-LABELS USE-TEXT.
END.

Notes

See also

ACCUM function, Aggregate phrase, DEFINE BROWSE statement, DEFINE FRAME statement, DOWN statement, EXPORT statement, FORM statement, Format phrase, Frame phrase, MESSAGE statement, PAGE statement, PUT statement, PUT SCREEN statement, Stream object handle, UP statement, VIEW-AS phrase

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