Expert Spring MVC and Web Flow

Listing 6-27.DateCommandBean Unit Test

protected void setUp() throws Exception {

bean = new DateCommandBean();

request = new MockHttpServletRequest();

binder = new ServletRequestDataBinder(bean, "bean");

}

public void testBind() throws Exception {

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");

Date expected = dateFormat.parse("2001-01-01");

CustomDateEditor dateEditor = new CustomDateEditor(dateFormat, true);

binder.registerCustomEditor(Date.class, dateEditor);

request.addParameter("date", "2001-01-01");

binder.bind(request);

assertEquals(expected, bean.getDate()); // true!

}

The registerCustomEditor(Class, PropertyEditor) (shown in Listing 6-27) configures

the DataBinderto use the PropertyEditorany time it encounters a property with the given

Class.

A second form, registerCustomEditor(Class, String, PropertyEditor), (not shown in

Listing 6-27) takes a third parameter, which is the full path name to a property. If you specify

the property name, the Classparameter can be null, but should be specified to ensure cor-

rectness. If the property name points to a collection, then PropertyEditoris applied to the

collection itself if the Classparameter is a collection, or to each element of the collection if

the Classparameter is not a collection.

Working with PropertyEditors not supported in the default set requires a bit more work,

but still results in a fairly simple setup. You will first create an instance of the CustomDateEditor

and provide it with your chosen DateFormatobject. The PropertyEditoris then registered with

the DataBinder, assigning it to a class it will be responsible for converting (in this case, the Date

class). After you register it, proceed as normal, and the CustomDateEditorwill handle any

property of type Date.

As you may guess, when you register a PropertyEditorwith the DataBinder, that

PropertyEditoris then used any time the Dateclass is encountered. While most times this

may be what you want, there are some situations where you may want two different date

formats for two different properties of the same object.

To handle this situation, you may register a PropertyEditorto be used for a specific

property, instead of for every instance of that class. Using this type of registration provides

very specific data binding on a per-property basis instead of the default per-class basis.

For example, we will create a command bean with two Dateproperties. One property we

will require the user to use the format YYYY-MM-DD, while the other property will require the for-

mat DD-MM-YYYY. We will create two CustomDateEditors, each with its own date parsing format.

Then, we will register each CustomDateEditorto their specific properties. Listing 6-28 contains

the new command bean with two Dates.

140 CHAPTER 6 ■THE CONTROLLER MENAGERIE