Скачать или смотреть Addressing the setValid(true) Requirement in JSF Custom Components

Learn whether invoking `setValid(true)` is necessary in the `decode()` method of a JSF custom component and explore the best practices for handling valid states.
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Understanding the Necessity of setValid(true) in JSF Custom Components

When you are developing a custom component in JavaServer Faces (JSF), you may encounter challenges related to the validation state of your component. One common concern is whether it is necessary to explicitly invoke setValid(true) in the decode() method of your custom component, particularly when extending from UIInput. This guide aims to clarify this issue and provide you with a deeper understanding of managing validation states in your JSF components.

The Problem at Hand

While working on a JSF custom component that inherits from UIInput, you may notice that the UIInput# getValid() method does not reset itself. Here’s a brief outline of the problem:

Custom Component: Inherits from UIInput and has its own converter, throwing a ConverterException for conversion failures.

Behavior on Validation: The component behaves as expected when a ConverterException occurs, but it does not reset its valid state on subsequent valid submissions.

The pressing question here is: Do you need to invoke setValid(true) during the Apply Request Values Phase of your JSF custom component?

Dissecting the Solution

To better understand the necessity of calling setValid(true), let's examine the behavior of the UIInput class and the options available in your implementation.

Default Behavior of UIInput# decode()

The UIInput# decode() method is designed to process input values submitted through the form. By default, this implementation calls EditableValueHolder# setValid(true), which is essential for marking the component as valid based on the submitted value.

Your Options

You have two main options regarding how to handle the setValid(true) invocation in your decode() method:

Invoke the Superclass Method:
The simplest approach is to call super.decode(context) within your overridden decode() method of the custom component. This inherits the default handling of submitted values and validity checks without requiring manual effort. Here’s how you can implement it:

[[See Video to Reveal this Text or Code Snippet]]

Manually Set Valid State:
If for some reason you prefer to manage the submitted value yourself, you can still follow the appropriate practices. Here’s how you can manually set the state before invoking setSubmittedValue():

[[See Video to Reveal this Text or Code Snippet]]

When to Choose Which Option

Option 1 (Invoke Super): This is generally recommended as it adheres to the default behavior of UIInput, ensuring consistency and reducing the potential for errors.

Option 2 (Manual Setting): Consider this option if you have specific requirements that necessitate customizing how the value is processed beyond what UIInput provides.

Conclusion

In summary, invoking setValid(true) in the decode() method of your JSF custom component can either be handled automatically by calling the superclass method or done manually based on your component's needs. For most developers, leveraging the existing functionality of UIInput is the best practice, ensuring that validation states are managed effectively without additional complexity.

By understanding the default behavior and knowing your options, you can create more robust JSF components and avoid potential pitfalls in user input handling.