Data Binding 

In Web Dynpro the connection between UI and Data is done by binding UI element properties to context attributes. Some UI elements have to be bound to nodes, but they contain children that have to be bound to attributes again. The Table for example is bound to a node, and the contained TableGroupedColumns have to be bound to attributes belonging to this node.

At runtime the UI element gets the data from the context elements. Depending whether the UI element can display a single value or multiple values, it has to be bound to an attribute that contains one or can contain multiple elements at runtime.

If a data binding of context element and UI element property is defined, the changes of the UI element property are directly transferred to the context and vice versa. These changes are also adopted by the properties of other UI elements of the same view if they are bound to the same context element.

For some UI elements you can distinguish between two variants of binding:

●      …ByIndex (for example DropDownByIndex)

In this case you have to provide a context node (cardinality=0..n) with elements storing the values and you have to determine the key from the index of these node elements. The selection is given by the nodes’s lead selection.

●      …ByKey (for example DropDownByKey)

In this case you have to provide a Dictionary type with a value set that contains key-value pairs. You have to bind the relevant UI element property to a context attribute of this dictionary type.