用s創建下拉菜單：selectItems

Question

我剛剛開始學習seam框架。我決定編寫兩個下拉菜單。一個列表類別和其他列表子類別。這個想法是，用戶將首先選擇一個類別，並取決於一個子類別將被填充。

<h:selectOneMenu value="#{manager.category}" required="true"> 
      <a:support event="onfocus" ajaxSingle="true" action="#{manager.dothis()}"/> 
      <s:selectItems value="#{manager.categories}" var="cat" label="#{cat.categoryDescription}" noSelectionLabel="Select a Category"/> 
      <s:convertEntity /> 

以上，我想打電話給dothis（）事件的焦點，但它不工作方法。

我在這裏做錯了什麼？

謝謝。

Answer 1

1. 您的＃{manager.categories}已經填充了嗎？
2. ＃{manager.dothis（）}做了什麼？

你可能不想做任何事情onfocus() ...除非你可能懶惰加載初始值（我認爲你不是）。您還應該重新編輯<a:support>標記中的內容，否則您的操作不會影響您網頁上的任何內容。

這裏是我的方式來處理（假設＃{} manager.categories填充）：

<h:selectOneMenu id="category" value="#{manager.category}" required="true"> 
      <a:support event="onchange" ajaxSingle="true" action="#{manager.populateSubCategories()}" reRender="subcategory"/> 
      <s:selectItems value="#{manager.categories}" var="cat" label="#{cat.categoryDescription}" noSelectionLabel="Select a Category"/> 
      <s:convertEntity /> 
</h:selectOneMenu> 

<h:selectOneMenu id="subcategory" value="#{manager.subcategory}" required="true"> 
      <s:selectItems value="#{manager.subcategories}" var="subcat" label="#{subcat.categoryDescription}" noSelectionLabel="Select a Sub-Category"/> 
      <s:convertEntity /> 
</h:selectOneMenu> 

Answer 2

這裏是我的豆：

@Stateful 
@Name("requestManager") 
public class RequestManagerBean implements RequestManager 
{ 
    @Logger private Log log; 

    @In StatusMessages statusMessages; 

    private Category category; 

    private Subcategory subcategory; 

    @Out(required=false) 
    private List categories; 

    private List subcategories; 

    @PersistenceContext 
    EntityManager entityManager; 
    public void createRequest() 
    { 
     // implement your business logic here 
     log.info("manager.createRequest() action called with: #{manager.value}"); 
     statusMessages.add("createRequest #{manager.value}"); 
    } 

    public Category getCategory() { 
     return category; 
    } 

    public void setCategory(Category category) { 
     this.category = category; 
    } 


    public Subcategory getSubcategory() { 
     return subcategory; 
    } 

    public void setSubcategory(Subcategory subcategory) { 
     this.subcategory = subcategory; 
    } 

    public List getCategories() { 
     return categories; 
    } 

    public void setCategories(List categories) { 
     this.categories = categories; 
    } 

    public List getSubcategories() { 
     //System.out.println("returning " + subcategories.size() + "subcategories.."); 
     return subcategories; 
    } 

    public void setSubcategories(List subcategories) { 
     this.subcategories = subcategories; 
    } 

    @Destroy 
    @Remove 
    public void destroy() {} 

    @Factory("categories") 
    public void loadCat() { 
     System.out.println("loadCat called.........."); 
     categories = entityManager.createQuery("select c from Category c order by c.categoryDescription").getResultList(); 
    } 

    public void callme() { 

     System.out.println("callme............"); 
     subcategories = category.getSubcategoryList(); 
     System.out.println(subcategories.size()); 
    } 
}

和形式

 
 

<rich:panel> 
     <f:facet name="header">Create Request</f:facet> 
     <h:outputText value="Category: "/> 
     <h:selectOneMenu id="categoryField" value="#{requestManager.category}"> 
      <s:selectItems var="cat" value="#{categories}" label="#{cat.categoryDescription}" noSelectionLabel="Select a Category"/> 
      <s:convertEntity /> 
      <a:support event="onchange" ajaxSingle="true" action="#{requestManager.callme}" reRender="subcategoryField" /> 
     </h:selectOneMenu> 
     <br /> 
     <br /> 
     <h:outputText value="Subcategory: "/> 
     <h:selectOneMenu id="subcategoryField" value="#{requestManager.subcategory}" required="true"> 
        <s:selectItems value="#{requestManager.subcategories}" var="subcat" label="#{subcat.subcategoryDescription}" noSelectionLabel="Select a Sub-Category"/> 
       <s:convertEntity /> 
     </h:selectOneMenu> 

     <div style="clear:both"/> 

    </rich:panel> 

    <div class="actionButtons"> 
     <h:commandButton id="createRequest" value="Submit" 
       action="#{requestManager.createRequest}"/> 
    </div> 

</h:form> 

/預>