The List and Combo controls, on the Controls palette, allow you to display data returned by a query as options in a list box.
You can display one set of values in the list box and specify another set of undisplayed values associated with the display values. Thus, you can provide text values, such as country names, in the control but pass less intuitive options, such as geospatial boundaries, to other QMF Visionary objects, such as a linear map.
List and Combo controls have three properties that determine the displayed list options, the value of the control to be passed, and the default value of the control:
When your user selects a value in the list, the selection sets the List.Value property for the control. The Value property is equal to the corresponding value of ValueList, if it is defined, otherwise OptionList. You can design an event action that occurs based on the option selected by the user. See Creating event actions for information on creating event actions.
You can set the Value property to a parameter or function to define the default value of the list box.
If you want to base which option is selected on the action of the user from another object, use a global parameter. Set the Value property for the control equal to the parameter.
Set the ValueList property when you want the value sent to a parameter or event to be different than the value selected to the user (set by the OptionList property).
When a user selects an option from the list, the row from ValueList that corresponds to the same row number from the chosen option is passed to the event or parameter.
You can define the ValueList property in two ways:
To specify a static list, click the button at the end of the OptionList or ValueList value cells.
To specify a column returned by a query, use the Field() function for the OptionList and ValueList properties, and the FieldValue() function for the Value property: