Multiple row selection

Multiple row selection allows the end user to select several rows in a list of records.

The DISPLAY ARRAY controller supports multiple row selection when the ON SELECTION CHANGE block is defined, or by enabling the feature with the ui.Dialog.setSelectionMode() method when the dialog starts. The setSelectionMode() method can also be used to enable or disable the multi-row selection during the dialog execution.

Important: This feature is not supported on mobile platforms.

When multi-row selection is enabled, the end user can select one or several rows with the standard keyboard and mouse click combinations. When the end user selects or de-selects rows, the ON SELECTION CHANGE block is fired, if defined. The program can then query the DIALOG.isRowSelected() method to check for selected rows.

DISPLAY ARRAY arr TO sr.*
  ...
  ON SELECTION CHANGE
     FOR i=1 TO DIALOG.getArrayLength("sr")
         DISPLAY SFMT("Row: %1 s=%2", i, DIALOG.isRowSelected("sr", i) ) 
     END FOR
  ON ACTION enable_mrs
     CALL DIALOG.setSelectionMode( "sr", 1 )
  ON ACTION disable_mrs
     CALL DIALOG.setSelectionMode( "sr", 0 )
  ...
END DISPLAY

Multiple row selection is GUI-specific and therefore can't be used in TUI mode.

With multiple row selection, you must distinguish between two concepts: row selection and current row. In GUI mode, a selected row usually has a blue background, while the current row has a dotted focus rectangle. The current row may not be selected, or a selected row may not be the current row. When the default single-row selection is used, the current row is always selected automatically.

If the ON SELECTION CHANGE block is not required, use the ui.Dialog.setSelectionMode() method to enable multi-row selection for the dialog:

DISPLAY ARRAY arr TO sr.*
  BEFORE DISPLAY
     CALL DIALOG.setSelectionMode( "sr", 1 )
  ...
END DISPLAY

Note however that without the ON SELECTION CHANGE trigger, it is not possible to detect row selection change when staying on the current row, since no BEFORE ROW / AFTER ROW trigger is fired in this case.

Row selection flags can be changed by program for a range of rows with the DIALOG.setSelectionRange() method.

The DISPLAY ARRAY dialog implements an implicit row-copy feature: The selected rows can be dragged to another dialog or external program, or the end-user can do an "editcopy" predefined action (Ctrl-C shortcut), to copy the selected rows to the front-end clipboard. The row-copy feature works also when multiple row selection is disabled, but only the current row will be dragged or copied to the front-end clipboard.

If you delete, insert or append rows in the program array with methods such as array.deleteElement(), selection information is not synchronized: To sync the selection flags with the data rows, use dialog methods like DIALOG.insertRow() (or DIALOG.insertNode() for tree-views), .

Behavior of ui.Dialog class methods with multiple row selection

Table 1. Effect of ui.Dialog class on selection flags when multi-range selection is enabled
Dialog class method	Effect on multiple row selection
`appendRow()`	Selection flags of existing rows are unchanged. New row is appended at the end of the list with selection flag set to zero.
`appendNode()`	Selection flags of existing rows are unchanged. New node is appended at the end of the tree with selection flag set to zero.
`deleteAllRows()`	Selection flags of all rows are cleared.
`deleteRow()`	Selection flags of existing rows are unchanged. Selection information is synchronized (i.e., shifted up) for all rows after the deleted row.
`deleteNode()`	Selection flags of existing rows are unchanged. Selection information is synchronized (i.e., shifted up) for all nodes after the deleted node.
`insertRow()`	Selection flags of existing rows are unchanged. Selection information is synchronized (i.e., shifted down) for all rows after the new inserted row.
`insertNode()`	Selection flags of existing rows are unchanged. Selection information is synchronized (i.e., shifted down) for all nodes after the new inserted node.
`setArrayLength()`	Selection flags of existing rows are unchanged. If the new array length is larger than the previous length, selection flags of new rows are not initialized to zero.
`setCurrentRow()`	Selection flags of all rows are reset, and the new current row gets selected.
`setSelectionMode()`	When you switch off multiple row selection, the selection flags of existing rows are cleared.