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That's why we haven't talked about models so far, and why this chapter discusses these two topics together.Model is essentially a facade interface which allows components to access and modify their data without knowing any detail about how they are managed or persisted.
However, despite their fundamental role, in Wicket models are not difficult to understand but the best way to learn how they work is to use them with forms.In Wicket, a user action typically triggers an event on one of the form components, which in turn responds to the event through strongly typed event listeners.Some of the other frameworks that fall in this category are Tapestry, JSF, and ASP. Essentially, frameworks like Struts gave birth to a concept of web-MVC that comprises coarse-grained actions-in contrast to the fine-grained actions we developers are so used to when programming desktop applications.However, to set a validation rule on a Form Component we must add the corresponding validator to it.For example if we want to use a text field to insert an email address, we could use the built-in validator Email Address Validator to ensure that the inserted input will respect the email format [email protected] : Default feedback messages (like the one above for required fields) are stored in the file Application.Component-oriented frameworks such as Wicket bring this more familiar programming experience to the Web.
Wicket relies on the Java servlet specification and accordingly requires a servlet container that implements the specification (servlet specification 2.3 and above) in order to run Wicket-based web applications.A basic example of a validation rule is to make a field required.In paragraph 11.3 we have already seen how this can be done calling set Required(true) on a field.Then you will learn to develop interactive web pages using Wicket.Along the way, you will be introduced to some key Wicket concepts.properties placed inside Wicket the org.apache.wicket package.