12.1 Introduction to Validation and Conversion

ADF Faces input components have built-in validation capabilities. You set validation on a component either by setting the required attribute or by using one of the prebuilt ADF Faces validators. ADF applications also have validation capabilities at the model layer, allowing you to set validation on a binding to an attribute. In addition, you can create your own ADF Faces validators to suit your business needs.

ADF Faces input components also have built-in conversion capabilities, which allow users to enter information as Strings, and which the application can automatically convert to another data type, such as Date. Conversely, data stored as something other than a String can be converted to a String for display and updating.

Many components, such as selectInputDate, automatically provide this capability. Other components, such as inputText, automatically add a built-in ADF Faces or JSF reference implementation converter when you drag and drop from the Data Control Palette an attribute that is of a type for which a converter exists.

When validators or converters fail, associated error messages can be displayed to the user. These messages can be displayed in popup dialogs for client-side validation, or they can be displayed on the page itself next to the component whose validation or conversion failed.

Read this chapter to understand:

• The different types of validation and how to add the capability to your application

• The ADF Faces converters and how to use them in an application

• The different ways you can display error messages

• How errors are handled by the ADF Model and displayed by ADF Faces error message components

• How exceptions thrown by the ADF application are handled, and how to customize the error handling process