LISTBOX SELECT ROWS

Home

4D v20 R7

LISTBOX SELECT ROWS


LISTBOX SELECT ROWS ( {* ;} object ; selection {; action} )

Parameter	Type	Description
*	Operator	If specified, object is an object name (string) If omitted, object is a variable
object	Form object	Object name (if * is specified) or Variable (if * is omitted)
selection	Object, Collection	Object or collection describing the rows to select
action	Longint	lk replace selection (default if omitted), lk add to selection, lk remove from selection

Description

The LISTBOX SELECT ROWS command selects the rows of an entity selection or collection list box that correspond to the entities or objects in the selection parameter.

If you pass the optional * parameter, you indicate that the object parameter is an object name (string). If you do not pass this parameter, you indicate that the object parameter is a variable. In this case, you pass a variable reference instead of a string. For more information about object names, refer to the Object Properties section.

In the selection parameter, pass an Object or a Collection depending on the list box type:

Entity selection list box

For an entity selection list box, pass an entity selection object containing entities of the same dataclass as the list box. If selection is an entity selection object from a different dataclass than the list box, an error is returned.

Collection list box

For a collection list box, pass a subcollection of objects belonging to the list box. If your list box contains scalar values, pass a subcollection of values.

Notes:

If selection is not a valid entity selection object / collection, an error is returned.
If selection is an empty entity selection / collection, by default (with "replace" action, see below) all the rows of the list box are deselected. For other actions, the command does nothing.
If selection contains entities / elements that are not displayed in the list box, they are ignored.

The optional action parameter, if passed, is used to define the selection action to execute when a selection of rows already exists in the list box. You can pass a value or one of the following constants (located in the “List Box” theme):

Constant	Type	Value	Comment
lk add to selection	Longint	1	The row selected is added to the existing selection. If the row specified already belongs to the existing selection, the command does nothing.
lk remove from selection	Longint	2	The row selected is removed from the existing selection. If the row specified does not belong to the existing selection, the command does nothing.
lk replace selection	Longint	0	The row selected becomes the new selection and replaces the existing selection. The command has the same effect as a user click on a row (however, the On Clicked event is not generated). This is the default action (if the action parameter is omitted).

By default, if the action parameter is omitted, the command replaces the row(s) defined by the selection parameter.

Note: The command assumes that each object or entity is displayed only once in the list box.

Example 1

This code allows you to select invoices in an entity selection using only a single server request:

  //On the On Load event of the form we have: Form.invoices:=ds.Invoices.all()

  //The ListBox "Invoices" displays the entity selection Form.invoices

 

 C_OBJECT($cash)

 C_OBJECT($card)

 

  //Select invoices paid with cash

 $cash:=Form.invoices.query("paymentMethod=:1";"Cash")

 LISTBOX SELECT ROWS(*;"Invoices";$cash;lk replace selection)

Example 2

Example with a collection of objects:

 C_TEXT($name)

 $name:=Request("Enter a name")

 If(OK=1)

  // Form.studentsColl is a collection of objects

    $selection:=Form.studentsColl.query("lastname = :1";$name)

    LISTBOX SELECT ROWS(*;"LBStudents";$selection;lk add selection)

 End if