PRB: List from Array May Display Incorrect Number Of Elements

ID: Q137179

The information in this article applies to:

Microsoft Visual FoxPro for Windows, version 3.0

SYMPTOMS

When an array that is the RowSource for a list box is redimensioned to a lower number of elements than originally displayed in the list box, there will be blank rows in the list representing elements from the previous array.

RESOLUTION

Issue one of the following (assuming the list box is placed on the form and is named List1) after redimensioning the array to allow the list box to display the correct number of elements:

   Thisform.List1.NumberOfElements=_TALLY
   * This can be used only if _TALLY is updated when the array is
   * redimensioned, with SELECT... INTO ARRAY or COPY TO ARRAY

   -or-

   Thisform.List1.Requery

   -or-

   Thisform.List1.RowSource=Thisform.List1.RowSource

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Type OPEN DATA in the Command window and select the

   Vfp\Samples\Data\Testdata.dbc database.

2. Type the following command in the Command window:

   SELECT country FROM CUSTOMER INTO ARRAY test

3. Create a new form, and put a list box object as well as a command button

   on the form.

4. In the properties for the list box, set the RowSource property to test

   and the RowSourceType to Array.

5. Place the following code in the command button's Click event procedure:

   SELECT country FROM CUSTOMER WHERE country="Germany" INTO ARRAY test
   Thisform.Refresh

   This code will change the size and contents of the array and allow the
   new contents to be displayed in the list box.

6. Run the form. Click the command button, and note "Germany" will appear

   in the list box, but a number of empty rows will appear at the bottom of
   the list. These empty rows correspond to the difference in the number of
   array elements created by the first and second SELECT commands.

Example Resolution

Modify the code in the click event of the command button, and add any one of the following after the SELECT command. This will allow the list box to display the array elements without the blank rows at the bottom of the list:

Thisform.List1.NumberOfElements=_TALLY
-or-
Thisform.List1.Requery
-or-
Thisform.List1.RowSource=Thisform.List1.RowSource

NOTE: There may be performance differences between the above methods with large arrays. Use whichever technique provides the best performance.

Additional reference words: 3.00 VFoxWin KBCategory: kbtool kbprb KBSubcategory: FxtoolFormdes