Dropdownchoice not updating model
Any component can get/set its model as well as its data object using the 4 public shortcut methods listed in the class diagram above.
The two methods on Model Changed() and on Model Changing() are triggered by Wicket each time a model is modified: the first one is called after the model has been changed, the second one just before the change occurs.
Please note that a Wicket form can be submitted using a standard HTML submit button which is not mapped to any component (i.e. In the next chapter we will continue to explore Wicket forms and we will see how to submit forms using special components which implement interface A form should contain some input fields (like text fields, check boxes, radio buttons, drop-down lists, text areas, etc.) to interact with users.
Wicket provides an abstraction for all these kinds of elements with component org.apache.wicket.form.
In addition, models are also an important element for internationalization, as we will see in paragraph 12.6.Form Component: The purpose of Form Component is to store the corresponding user input into its model when the form is submitted.The form is responsible for mapping input values to the corresponding components, avoiding us the burden of manually synchronizing models with input fields and vice versa.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.
Every component has at most one related model, while a model can be shared among different components.
The topic of security will be discussed later in chapter 20.