OL98: How to Populate a List Box or Combo Box

ID: Q231164

The information in this article applies to:

SUMMARY

This article describes how to populate a list box or combo box control on an Outlook custom form.

NOTE: This article does not directly apply to using a Visual Basic for Applications UserForm, although some of the approaches in this article may be applied to UserForms.


MORE INFORMATION

There are a variety of ways to populate a list box or combo box on an Outlook form. The controls can be populated either at design-time or at run-time.

Populating List Boxes and Combo Boxes at Design-Time

If you have a predetermined and unchanging set of possible values, you can populate list boxes and combo boxes when designing the form. The following steps illustrate how to set up a simple list box control on an Outlook form.
  1. On the Tools menu, point to Forms, and then click Design a Form.


  2. In the Standard Forms Library, click Message, and then click Open.


  3. Click the (P.2) tab.


  4. On the Form menu, click Control Toolbox. On the Control Toolbox, drag a ListBox onto the form.


  5. Right-click the list box and then click Properties. On the Value tab, click New. Type ListBoxField for the name and click OK. In the Possible Values field, type Blue;Green;Red;Yellow, and then click OK.


  6. On the Form menu, click Run This Form.


Click the P.2 page of the form. You can then select any item in the list box and the selected value will be stored in the ListBoxField user-defined field.

NOTE: In step 5, instead of using a Text field, you can use a Keywords field to store the data for a list box (not a combo box). When a ListBox control is bound to a Keywords field, check boxes will appear next to the possible values in the list box and the user can make multiple selections. All of these selections are stored in the multi-value Keywords field. However, Keywords fields are limited to 255 characters, so this type of field should be used only if the user will be selecting from a relatively few possible values.

For more information about this limitation of the Keywords field, please see the following article in the Microsoft Knowledge Base:
Q196937 OL98: ListBox Bound to Keywords Field Unexpectedly Changes

Dynamically Populating List Boxes and Combo Boxes at Run-Time

Many solutions require that the possible values in a list box or combo box be up-to-date or refreshed regularly. The values are typically stored in some other location and need to be retrieved every time the item is opened. To accomplish this, you can add Visual Basic Scripting Edition (VBScript) code to the form and use an Item_Open event to run code whenever an item is opened. This code will fill the list box or combo box with possible values.

Microsoft provides programming examples for illustration only, without warranty either expressed or implied, including, but not limited to, the implied warranties of merchantability and/or fitness for a particular purpose. This article assumes that you are familiar with the programming language being demonstrated and the tools used to create and debug procedures. Microsoft support professionals can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific needs. If you have limited programming experience, you may want to contact a Microsoft Certified Solution Provider or the Microsoft fee-based consulting line at (800) 936-5200. For more information about Microsoft Certified Solution Providers, please see the following page on the World Wide Web:

http://www.microsoft.com/mcsp/
For more information about the support options available from Microsoft, please see the following page on the World Wide Web:

http://www.microsoft.com/support/supportnet/refguide/
There are various ways in which you can use VBScript to populate a list box or combo box.

PossibleValues Property

If you have a relatively simple list box or combo box to work with, you can automate the design-time steps by using the PossibleValues property of the control. This property is unique to Outlook and should be set to a semicolon-delimited string, just like the design-time steps earlier. To see how the PossibleValue property can be implemented, follow these steps:
  1. On the Tools menu, point to Forms, and then click Design a Form.


  2. In the Standard Forms Library, click Message, and then click Open.


  3. Click the (P.2) tab.


  4. On the Form menu, click Control Toolbox. On the Control Toolbox, drag a ListBox onto the form.


  5. Right-click the list box and then click Properties. On the Value tab, click New. Type ListBoxField2 for the name and click OK. Leave the Possible Values field blank and then click OK.


  6. On the Form menu, click View Code. Enter the following VBScript code and then close the Script Editor.


    7. 
Sub Item_Open()

   ' Sets the name of page on the form (P.2)
   Set FormPage = Item.GetInspector.ModifiedFormPages("P.2")

   ' Sets Control to a list box called ListBox1.
   Set Control = FormPage.Controls("ListBox1")

   ' Assign values to the list box.
   Control.PossibleValues = "Blue;Green;Red;Yellow"

End Sub
  7. On the Form menu, click Run This Form.


Click the P.2 page of the form. You can then select any item in the list box and the selected value will be stored in the ListBoxField2 user-defined field.

AddItem Method

The AddItem method is typically used when you are looping through a series of data. As you loop through the data, you add items to the list box or combo box one at a time.

For an example of using the AddItem method to populate a combo box, please see the following article in the Microsoft Knowledge Base:
Q180911 OL98: How to Populate a Combo Box with Your Contacts

List Property

List boxes and combo boxes have a List property that allows you to specify an array which contains the data the control should use. If your programming solution is already using arrays to store data, using this approach can provide the simplest programming solution. Also, one key advantage to using the List property is that if you wish to populate the list box or combo box with multi-column data, the List property supports multi-dimensional arrays to accomplish this.

To populate a two-column list box with data from your Contacts folder, following these steps:
  1. On the Tools menu, point to Forms, and then click Design a Form.


  2. In the Standard Forms Library, click Message, and then click Open.


  3. Click the (P.2) tab.


  4. On the Form menu, click Control Toolbox. On the Control Toolbox, drag a ListBox onto the form. Make sure the list box is sized large enough to fill most of the form page.


  5. On the Form menu, click View Code. Enter the following VBScript code and then close the Script Editor.


    6. 
Sub Item_Open()

   Dim FullArray()

   ' Sets the name of page on the form (P.2)
   Set FormPage = Item.GetInspector.ModifiedFormPages("P.2")

   ' Sets Control to a list box called ListBox1.
   Set Control = FormPage.Controls("ListBox1")

   ' Get the default Contacts folder
   Set ConFolder = Application.Session.GetDefaultFolder(10)

   ' Get the items in the folder
   Set ConItems = ConFolder.Items

   ' Get the number of total items in the Contacts folder
   NumItems = ConItems.Count

   ' Resize array to handle total number of item in the folder
   ReDim FullArray(NumItems-1,2)

   ' Loop through all of the items in the Contacts folder,
   ' filling the array with sample data and keeping track
   ' of the number of contacts found.
   NumContacts = 0
   For I = 1 to NumItems
      Set itm = ConItems(I)
      If Left(itm.MessageClass, 11) = "IPM.Contact" Then
         NumContacts = NumContacts + 1
         FullArray(NumContacts-1,1) = itm.FullName
         FullArray(NumContacts-1,2) = itm.CompanyName
      End If
   Next

   ' Set the control to handle 2 data columns
   Control.ColumnCount = 3

   If NumItems = NumContacts Then
      ' They are all contacts, so use the FullArray
      Control.List() = FullArray
   Else
      ' There's some distribution lists, so use the smaller
      ' ConArray to eliminate extra blank values in the listbox
      Dim ConArray()
      ReDim ConArray(NumContacts-1,2)
      For I = 0 to NumContacts - 1
         ConArray(I,1) = FullArray(I,1)
         ConArray(I,2) = FullArray(I,2)
      Next
      Control.List() = ConArray
   End If

End Sub
  6. On the Form menu, click Run This Form.


Click the P.2 page of the form. The list box will be populated with the data from your default Contacts folder.


REFERENCES

For more information about creating solutions with Microsoft Outlook 98, please see the following articles in the Microsoft Knowledge Base:

Q180826 OL98: Resources for Custom Forms and Programming
Q182349 OL98: Questions About Custom Forms and Outlook Solutions

Additional query words: OutSol OutSol98 98 


Keywords          : kbdta 
Version           : WINDOWS:
Platform          : WINDOWS 
Issue type        : kbinfo

Last Reviewed: June 16, 1999