Value Help in Web Dynpro Applications 

Purpose

The Web Dynpro runtime environment provides generic UI services for the application development. They enable you to easily create a value help for constants – for example, for countries or zip codes.

You can use the simple value selector as a dropdown list box to display a set of constants when you bind a DropdownByKey UI element to a value attribute of the type Simple Type. The simple value selector is especially useful for small sets of constant values (up to 30 entries).

If the dropdown list box is too long due to the large number of constant values in a simple data type Simple Type, you should use the extended value selector. This value selector can display a large set of constants in a special dialog box below a regular input field. The extended value selector also provides a sort function and search function. The main concept of this value help is to bind constants to an input field or a DropdownByKey UI element. The constants are contained in a simple data type Simple Type and the value attributes have the same type. With the exception of the possible dynamic data type modifications of a value attribute at runtime, the application developer must only implement the declarations involved. For further information, refer to Inserting an Extended Value Selector.

Features

You must carry out the following steps to be able to use use the value help:

·        Define a simple data type Simple Type that contains a set of constants

·        Statically assign a type based on the simple data type Simple Type to a value attribute

·        Dynamically assign a simple data type Simple Type to a value attribute at runtime

·        Use a simple or extended value selector to display a value help for constants on the user interface

Process Flow

The development process for the use of value selectors consists of the following four sections:

·        Example application of the simple value selector: This section is about the user interface to be developed.

·        Specifying the project structure: Before you can start the actual development of the example application, you must specify the basic project structure (Web Dynpro project, Web Dynpro component, Web Dynpro application).

·        Simple value selector: You learn the required development steps for displaying a short listing of constants in the simple value selector.

·        Extended value selector: This section describes how you can provide a value help for a large number of valid constants using the extended value selector. At runtime, the set of constants is dynamically passed to the data type of a value attribute.

 Familiarize yourself with Creating an Example Application of a Value Selector.