selectOneMenu 不渲染/显示值

Question

之前发表过一篇关于此主题的文章（在向下钻取 SelectOneMenus 中显示值< /a>）。正如我首先想到的那样，问题与对象转换器无关。

我有两个相互依赖的 selectOneMenu，Sector ->类别。当我保留包含部门和类别的后台业务对象时，一切都会按预期进行。即使当前用户会话终止并且用户再次登录并编辑先前保存的业务对象也是如此。

当实体管理器刷新对象并且用户想要再次从数据库显示扇区、类别时，就会出现问题。 Sector selectOneMenu 按其应有的方式显示其值，但 Category selectOneMenu 值未显示。尽管支持 bean 具有来自数据库的正确值。

当从数据库而不是内存中加载某些持久值/对象时，是什么导致 selectOneMenu 不显示它们？

Edit.xhtml

<h:outputLabel value="Sector:" />
<h:selectOneMenu id="sectorSelector" value="#{activityController.selected.category.sector}" title="#{bundle.CreateSectorLabel_sectorName}" valueChangeListener="#{activityController.changeSectorMenu}" immediate="true">
            <a4j:ajax event="change" execute="@this categoryMenu" render="categoryMenu"/>
            <f:selectItems value="#{sectorController.itemsAvailableSelectOne}"/>
</h:selectOneMenu>

<h:outputLabel value="Category:" />
    <h:selectOneMenu id="categoryMenu" value="#{activityController.selected.category}" title="#{bundle.CreateSectorLabel_sectorName}" 
        binding="#{activityController.categoryMenu}"
            required="true" requiredMessage="#{bundle.CreateCategoryRequiredMessage_sector}">                        
    <f:selectItems value="#{activityController.categorySelection}"/>
</h:selectOneMenu>

类别部分的控制器 bean

@ManagedBean(name = "categoryController")
@SessionScoped
public class CategoryController implements Serializable{

    ....

    @FacesConverter(forClass = Category.class)
    public static class CategoryControllerConverter implements Converter {

        @Override
        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            CategoryController controller = (CategoryController) facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "categoryController");
            return controller.ejbFacade.find(getKey(value));
        }

        java.lang.Integer getKey(String value) {
            java.lang.Integer key;
            key = Integer.valueOf(value);
            return key;
        }

        String getStringKey(java.lang.Integer value) {
            StringBuffer sb = new StringBuffer();
            sb.append(value);
            return sb.toString();
        }

        @Override
        public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
            if (object == null) {
                return null;
            }
            if (object instanceof Category) {
                Category o = (Category) object;
                return getStringKey(o.getIdCategory());
            }
            else {
                throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + CategoryController.class.getName());
            }
        }
    }

POJO 对象

...
public class Category implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "idCategory")
    private Integer idCategory;
    ...

    @Override
    public boolean equals(Object object) {
        if (!(object instanceof Category)) {
            return false;
        }
        Category other = (Category) object;
        if ((this.idCategory == null && other.idCategory != null) || (this.idCategory != null && !this.idCategory.equals(other.idCategory))) {
            return false;
        }
        return true;
}

用于创建 SelectItem[] 数组的函数

public static SelectItem[] getSelectItems(List<?> entities, boolean selectOne) {

        int size = entities.size();
        SelectItem[] items;
        int i = 0;
        if (selectOne) {
            items = new SelectItem[size + 1];
            items[0] = new SelectItem("", ResourceBundle.getBundle("/resources/Bundle").getString("Select_item"));
            i++;
        } else {
            items = new SelectItem[size];
        }

        for (Object x : entities) {
            items[i++] = new SelectItem(x, x.toString());
        }
        return items;
    }

Answer 1

问题是，当用户编辑业务对象时，我没有正确的 SelectItems 集合。另外，我添加了 来显式调用转换器，其中我在 getAsString() （else 部分）中做了一些更改。

感谢您抽出宝贵的时间，希望这篇文章对其他人有用。

SelectMenuOne

public String prepareEditOrganisationActivity() {
        current = (Activity) organisationActivityItems.getRowData();
        Sector sector = current.getCategory().getSector();
        CategoryController categoryBean = JsfUtil.findBean("categoryController", CategoryController.class);
        categorySelection = categoryBean.categoryItemsBySector(sector);

        return "EditActivity";
}

类别控制器转换器

...    
    @Override
    public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
        if (object == null) {
            return null;
        }
        if (object instanceof Category) {
            Category o = (Category) object;
            return getStringKey(o.getIdCategory());
        }
        else {
            Category tmp = new Category();
            return getStringKey(tmp.getIdCategory());                
        }
    }