How to Simulate a Combo Box in FoxPro for Windows

• Microsoft FoxPro for Windows, version 2.6a

SUMMARY

A combo box is a object into which you can enter data directly or select an item from a predefined drop-down list. FoxPro does not have a combo box option to choose when making a screen, but you can use the technique presented in this article to simulate a combo box in FoxPro.

MORE INFORMATION

The code in the VALID clause of the GET object will vary depending on where the information for the drop-down list comes from: arrays, a field from a table, or defining bars for the popup box. Use the following steps to make a combo box by using a popup with a predefined list:

1. Create a screen in FoxPro, and add a GET object to the screen, giving it the variable name of COMBO. Make sure it is a character field.

2. In the VALID clause of the object COMBO, add the following code:

   IF EMPTY(combo)

         DEFINE POPUP combobox FROM 7,25 to 14,50
         DEFINE BAR 1 OF combobox PROMPT 'Choice 1'
         DEFINE BAR 2 OF combobox PROMPT 'Choice 2'
         DEFINE BAR 3 OF combobox PROMPT 'Choice 3'
         DEFINE BAR 4 OF combobox PROMPT 'Choice 4'
         DEFINE BAR 5 OF combobox PROMPT 'Choice 5'
         ON selection popup combobox DO getcombo WITH PROMPT()
         ACTIVATE POPUP combobox
   

   ENDIF SHOW GETS

3. In the cleanup code of the screen, add the following code:

   PROCEDURE getcombo

   PARAMETER mprompt combo=mprompt

      KEYBOARD '{TAB}'           && Moves you off of the popup after
                                 &&pressing ENTER to select your choice.
   
   

4. Add a push button to the screen; call it EXIT. In the VALID clause, put the code CLEAR READ.

Adjust the coordinates in the DEFINE POPUP statement if you want the popup to overlay the get field exactly. The example code shows how to define bars for the popup. If you want information from a field to be listed in the popup, change the code as indicated below.

NOTE: This code uses the CUSTOMER.DBF file located in the TUTORIAL subdirectory of FoxPro.

In the VALID clause of the COMBO GET object, change the code to match this:

   IF EMPTY(combo)
      DEFINE POPUP combobox PROMPT FIELD cno FROM 6,29 TO 12,43
      ON SELECTION POPUP combobox DO getcombo
      ACTIVATE POPUP combobox
   ENDIF
   SHOW GETS

   PROCEDURE getcombo

   combo=<fieldname>     && This is the fieldname that follows the PROMPT
                         && FIELD clause in the DEFINE POPUP
   KEYBOARD '{TAB}'