JSF2：带有自定义selectItems的selectOneMenu：选择所有项目

Question

Thanks to some great articles here, I've been able to build a <h:selectOneMenu /> with selectItems containing objects. After providing a custom FacesConverter and fixing the missing equals()/hashcode() methods, I am able to use it to change the property of the backing bean and write it out to the DB.

The only weird thing is that all HTML <option /> elements of the <select /> -element are checked="checked" ! In other words: the <h:selectOneMenu /> does not reflect the current value of the bound property!

Details:

Store.java

@Entity
public class Store {
  private Long id;
  private String name;

  @ManyToOne
  private Category category;

  // getters, setters, equals, hashcode
}

Category.java

@Entity
public class Category {
  private Long id;
  private String name;

  // getters, setters, equals, hashcode
}

editStore.xhtml

<h:form>
....
  <h:selectOneMenu value="#{backingBean.store.category}" id="category">
    <f:selectItems value="#{backingBean.categorySelectItems}" />
  </h:selectOneMenu>
....
</h:form>

BackingBean.java

public class BackingBean {
  private Store store;

  // inject data-access-facades via @EJB
  // Constructor
  // getters, setters

  public List<SelectItem> getCategorySelectItems
    List<SelectItem> items = new ArrayList<SelectItem>();
    for (Category cat : categoryFacade.findAll() ) {
      items.add(new SelectItem(cat, cat.getName()));
    }
    return items;
  }

  // action methods
}

I leave out listing the Category-Converter (it converts between the object and its ID).

The HTML this creates is:

<select id="category" name="category" size="1">
  <option value="251" selected="selected">Kosmetik</option>
  <option value="222" selected="selected">Sportwaren</option>
</select>

Obviously, store.category can only contain one item... why are both option-elements "selected"? No matter, what category is assigned to the store, the HTML always "selects" all option-elements.

How does JSF now, which SelectItem should be selected?

Answer 1

It's almost certain that the problem is in the equals(..) method, which returns true for all compared objects. Test this, and let your IDE generate the method (together with hashCode() )