How to Add a New Value to a List of Values in a Combo Box

• Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

The RowSourceType property of a combo box can be set to Value, and a list of values can be specified for the row source. This article illustrates how you can input a value that is not in the list.

MORE INFORMATION

If the ControlSource property for the combo box is set to a field in the underlying table, the value chosen from the combo box will be written to that field when the record is saved. But if the value to be stored is not in the list assigned to the row source, the value is not written to the field.

To store that non-list value to the field, you need a way to:

1. Store the value, which by default is not stored.

2. Update or refresh the list in the combo box so that if a non-list value is stored to the table, that value reappears in the list for that record and only that record.

Step-by-Step Example

The following steps illustrate how to input a value that is not in the list of values for a combo box:

1. Create a table called Test that has a single character field that is also called Test by entering the following code in a program file and then running the program. (Make sure you don't already have a table named Test in your current directory:

   CREATE TABLE test (test c(10)) INSERT INTO test (test) VALUES("pigs") INSERT INTO test (test) VALUES("sheep") INSERT INTO test (test) VALUES("hippos") INSERT INTO test (test) VALUES("pigs") INSERT INTO test (test) VALUES("sheep") INSERT INTO test (test) VALUES("hippos")

2. Create a new form (Form1), and add a combo box (Combo1) to it.

3. Add the Test table to the form's data environment.

4. Set the RowSourceType property of the combo box to 1-Value.

5. Enter the following for the RowSource property of the combo box:

   pigs,sheep,hippos

6. Set the ControlSource property of the combo box to a field in your table. This example assumes that the field is called Test, so the entry would be:

   Test.Test

7. Add a property to the form and name it cdspval. This property will be used to keep track of the current DisplayValue of the Combo Box.

8. Place the following code in the Combo1 Valid event:

   * This code writes the user's value to the test.test field * if the value does not appear in the list: if !empty(this.displayvalue)

         if upper(this.displayvalue. != 'PIGS' and;
            upper(this.displayvalue. != 'SHEEP' and;
            upper(this.displayvalue. != 'HIPPOS'
               replace test.test with this.displayvalue
               thisform.combo1.additem(alltrim(test.test))
         endif
      else
         replace test.test with thisform.cdspval
      endif
      thisform.cdspval=""
      thisform.refresh
   
   

9. Place the following code in the Combo1 GotFocus event:

   thisform.cdspval=this.displayvalue thisform.combo1.rowsource = 'pigs,sheep,hippos' if alltrim(upper(test.test))!="PIGS" and;

         alltrim(upper(test.test))!="SHEEP" and;
         alltrim(upper(test.test))!="HIPPOS"
            if !empty(test.test)
               thisform.combo1.additem(alltrim(test.test))
            endif
      endif
   
   

10. Place the following code in the Combo1 LostFocus event:

    * This code returns the combo1.rowsource list to its original value * before another object gains the focus this.rowsource = 'pigs,sheep,hippos'

11. Place the following code in the Combo1 Refresh event:

    Form1.Refresh thisform.combo1.gotfocus()