I think the heading of this article explains what the project is all about. I have created a new web user control based on DropdownList server control. But the new control has a little twist to it. The entries in the dropdown combobox are not displayed as flat. You can configure the combo box to display entries with indentations. It is very much on the same lines as Master/Detail data grid. The top level entry, Master entry, display the main category and then indented entries, Detail data, is displayed with amount of indentation you specify.

Input to control

You will have to provide 2 DataTable objects to the control. One is called MasterTable and the other is called DetailTable. You will also need to specify the names of the fields that will be used to establish foreign key constraint between the two tables. And the last requirement is providing the names of the fields whose values need to be shown in the dropdown list.

What is configurable?

You can specify the following properties to customize the appearance.

• IndentSpace: This value sets the identation space from the left of the control
• IndentMark: This string will be displayed in front of the detail entries. Default value is "-". By setting an empty string you can clear the mark.
• MasterBackgroundColor: This value sets the background color for the master enteries.
• MasterForeColor: This value sets the foreground or text color for the master entries.
• DetailBackgroundColor: This value sets the background color for the detail enteries.
• DetailForeColor: This value sets the foreground or text color for the detail entries.

How do i get the selected value?

The control appends the master and detail key field names with the values stored in it. This appended value is set as Value of ListItem. You can parse the values of the selected item to get the actual value stored in it.