ACC: Error "Invalid key" When Adding Node to TreeView Control

• Microsoft Access versions 7.0, 97

SYMPTOMS

Advanced: Requires expert coding, interoperability, and multi-user skills.

When you try to use the Add method of the Node object with the TreeView Custom Control, you may receive the following error message:

   Run-time error '35603':
   Invalid key

CAUSE

The Item Method, which can be used to return a specific member of the Nodes collection, takes one argument. If this argument is a numeric expression, the Item method searches for the Node by index; if the argument is a string expression, the Item method searches for the Node by key. Because this argument is a Variant, the Item method cannot distinguish a key expression from an index expression unless that expression contains at least one non- numeric character.

RESOLUTION

Concatenate at least one non-numeric character to the expression in the key argument of the Add method. For example, add a node by using

   Set Node = Me!CustOrders.Nodes.Add(, , "Node " & rst!OrderID,
   CStr(rst!OrderID))

   Set Node = Me!CustOrders.Nodes.Add(, , rst!OrderID, CStr(rst!OrderID))

MORE INFORMATION

Steps to Reproduce Behavior

1. Open the sample database Northwind.mdb.

2. Create a new form not based on any table or query.

3. Insert a TreeView Control and name it CustOrders.

4. Set the form's OnLoad property to the following [Event Procedure]

        Private Sub Form_Load()
            Dim db As DATABASE, rst As Recordset
            Dim Node As Object
            Set db = CurrentDb()
            Set rst = db.OpenRecordset("Orders", dbOpenDynaset)
            If rst.RecordCount > 0 Then
                Do Until rst.EOF
                    Set Node = Me!CustOrders.Nodes.Add(, , _
                            st!OrderID,cstr(rst!OrderID))
                    rst.MoveNext
                Loop
            End If
            rst.Close
            db.Close
        End Sub
   
   

5. Open the form in Form View. Note that you receive the following error message:

         Run-time error '35603':
         Invalid Key
   

   The error occurs even if you use the Cstr() function with the key argument (the third argument of the Add method).

REFERENCES

For more information about the Add method of the Node object, search the Help Index for "Add Method," and then "Add Method (Nodes Collection)."