Working with WebDataLink Interfaces

Note: DB Web Controls (Borland.Data.Web namespace) are being deprecated in 2007. You should use standard Web controls instead.

The characteristic that makes DB Web Controls different from traditional web controls is that the DB Web Controls automatically handle all data binding for you. Although you must still configure the links between data sources and controls at design time, all runtime binding is handled, without the need for you to add a data binding command in your code. When extending a DBWeb control using the DBWeb Control Wizard, you will implement several interfaces that provide the data binding capabilities. These interfaces are discussed in this topic.

IDBWebDataLink
IDBWebColumnLink: IDBWebDataLink
IDBWebLookupColumnLink: IDBWebColumnLink

IDBWebDataLink

All DB Web Controls implement this interface. The interface defines a data source and a data table, allowing you to connect to and access data from a variety of data sources, including databases, text files, arrays, and collections. If your control only needs to access data at the table level, you implement this interface.

IDBWebColumnLink:IDBWebDataLink

This interface is implemented by DBWeb column controls, such as DBWebImage,DBWebTextBox, and DBWebCalendar, among others. The interface defines a column name to which a column control is linked. In combination with the IDBWebDataLink interface, this interface provides access to standard table and column data.

IDBWebLookupColumnLink:IDBWebColumnLink

This interface is implemented by DBWeb lookup controls, such as DBWebListBox,DBWebRadioGroup, and DBWebDropDownList. The interface defines a TableName within a DataSet, a ColumnName representing a table that contains the data to be displayed in the lookup, and the column containing the values which, when a value is selected, are to be placed into the ColumnName field linked to the control. By default, the ColumnName field is the same as DataTextField. Lookup controls contain not only a text property, usually the item that is displayed in the control, such as a listbox, but also a value property. The value property might be identical to the text property, or it might contain a completely different piece of data, such as an identification number. For example, you might choose to display product names in a listbox or a drop down listbox, but set the values for each displayed item to their respective product IDs. When a user selects a product name, the product ID is passed to the application, rather than the name of the product itself. One benefit of this approach is to eliminate processing confusion between products with similar names.