2
我有這些簡單的網頁：JSF 2基本@RequestScoped CRUD
list.xhtml
<h:form id="form">
<h:dataTable value="#{testBean.model}" var="elem">
<h:column>
<f:facet name="header">code</f:facet>
#{elem.code}
</h:column>
<h:column>
<f:facet name="header">description</f:facet>
#{elem.description}
</h:column>
<h:column>
<f:facet name="header">action</f:facet>
<h:commandButton action="#{testBean.edit(elem)}" value="edit"/>
</h:column>
</h:dataTable>
</h:form>
edit.xhtml
<h:form id="form">
<h:panelGrid columns="2">
<h:outputLabel value="code"/>
<h:inputText value="#{testBean.selection.code}"/>
<h:outputLabel value="description"/>
<h:inputText value="#{testBean.selection.description}"/>
</h:panelGrid>
<h:commandButton action="#{testBean.update}" value="update"/>
</h:form>
和這個bean：
@ManagedBean
public class TestBean implements Serializable
{
private static final long serialVersionUID = 1L;
@EJB
private PersistenceService service;
private Object selection;
private List<UnitType> model;
@PostConstruct
public void init()
{
model = service.findAll(UnitType.class);
}
public String edit(Object object)
{
System.out.println(Tracer.current(object));
setSelection(object);
return "edit";
}
public String update()
{
System.out.println(Tracer.current(selection));
return "list";
}
// getters and setters
}
所以桌子被渲染，當我點擊其中一個E「編輯」按鈕，將定位爲「edit.jsf」顯示填充輸入， 但是當我點擊「更新」按鈕，它給了我這個錯誤：
javax.el.PropertyNotFoundException: /test2/edit.xhtml @27,54 value="#{testBean.selection.code}": Target Unreachable, 'null' returned null
注意，我知道如何實現@ViewScoped接口來管理CRUD操作，但這是一個簡單的概念證明，我需要更好地理解JSF生命週期。
，所以我想 「testBean就」 被@RequestScoped
UPDATE與f:viewParam努力，仍然不理解......
list.xhtml
<?xml version="1.0" encoding="ISO-8859-1"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core">
<h:head>
<title>test list</title>
</h:head>
<h:body>
<h:messages/>
<h:form id="form">
<h:dataTable value="#{testBean2.model}" rows="10" var="elem">
<h:column>
<f:facet name="header">converterString</f:facet>
#{elem.converterString}
</h:column>
<h:column>
<f:facet name="header">first name</f:facet>
#{elem.firstName}
</h:column>
<h:column>
<f:facet name="header">last name</f:facet>
#{elem.lastName}
</h:column>
<h:column>
<f:facet name="header">action</f:facet>
<h:commandButton action="#{testBean2.edit}" value="edit">
<f:param name="entity" value="#{elem.converterString}"/>
</h:commandButton>
<h:commandButton action="#{testBean2.edit2}" value="edit2">
<f:param name="entity" value="#{elem.converterString}"/>
</h:commandButton>
</h:column>
</h:dataTable>
</h:form>
</h:body>
</html>
edit.xhtml
<?xml version="1.0" encoding="ISO-8859-1"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core">
<f:metadata>
<f:viewParam id="entityParam" name="entity" value="#{testBean2.selection}" converter="entityConverter" required="true"/>
</f:metadata>
<h:head>
<title>test edit</title>
</h:head>
<h:body>
<h:messages/>
<h:form id="form">
<h:panelGrid columns="2">
<h:outputLabel value="selection"/>
<h:outputText value="#{testBean2.selection.converterString}"/>
<h:outputLabel value="firstName"/>
<h:inputText value="#{testBean2.selection.firstName}"/>
<h:outputLabel value="lastName"/>
<h:inputText value="#{testBean2.selection.lastName}"/>
</h:panelGrid>
<h:commandButton action="#{testBean2.update}" value="update" ajax="false">
<f:param name="entity" value="#{testBean2.selection.converterString}"/>
</h:commandButton>
</h:form>
</h:body>
</html>
testBean2.java
@ManagedBean
public class TestBean2 implements Serializable
{
private static final long serialVersionUID = 1L;
@EJB
private PersistenceService service;
private Object selection;
private List<Person> model;
@PostConstruct
public void init()
{
Tracer.out();
model = service.queryAll(Person.class);
}
public String edit()
{
JsfUtils.addSuccessMessage("edited");
return "edit";
}
public String edit2()
{
JsfUtils.addSuccessMessage("edited");
return "edit?faces-redirect=true&includeViewParams=true";
}
public void update()
{
Tracer.out(selection);
JsfUtils.addSuccessMessage("updated");
}
// getters and setters
}
如果我按「編輯」按鈕，它去edit頁，但選擇爲空，沒有消息顯示。
如果我按「EDIT 2」按鈕，它去edit頁，但選擇爲空，顯示所需信息，網址爲edit.jsf?entity=
我到底做錯了什麼？
閱讀本你會g等想法 [在管理豆查看和請求範圍的差異] [1] [1]：http://stackoverflow.com/questions/6025998/difference-between-view-and-請求範圍在受管理的豆 – 2012-08-16 11:47:43
我已經知道區別。我正在問一些不同的東西。請仔細閱讀這個問題。 – 2012-08-16 11:53:18
嗨米歇爾，你能解決上述問題嗎？我正在使用請求範圍來執行CRUD。你得到同樣的錯誤。 – Unknown 2014-11-04 05:15:18