h:commandButton 一旦我将它包装在一个 <h:panelGroup 渲染> 中就不起作用了. [英] h:commandButton is not working once I wrap it in a <h:panelGroup rendered>

查看：15 发布时间：2021/12/31 9:58:47 jsf-2 primefaces facelets jsf-2.2 commandbutton

本文介绍了h:commandButton 一旦我将它包装在一个 <h:panelGroup 渲染> 中就不起作用了.的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

主题之所以有某种"，是因为我在 JSF 2.2 中有一个示例，其中我使用 commandButton 并两次调用 bean 函数(取决于 url).基本上都是一样的代码，只在一个例子中执行.

The reason why the topic has "kind of" is because I have an example in JSF 2.2 where I use a commandButton and call a bean function twice (depending on the url). It's basically the same code, which executes only in one example.

这是代码下方的错误"描述:

Here's the code with the description of the "error" below the code:

用户豆

@ManagedBean
@RequestScoped
public class User {

private String name;
private String surname;
private int age;
private int id;

public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}

public String getSurname() {
    return surname;
}
public void setSurname(String surname) {
    this.surname = surname;
}

public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}

public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}

public User(String name, String surname, int age, int id) {
    super();
    this.name = name;
    this.surname = surname;
    this.age = age;
    this.id = id;
}

public User(){}

}

UsersBean 豆:

UsersBean bean:

@ManagedBean
@SessionScoped
public class UsersBean {

private List<User> listOfUsers = new ArrayList<User>();
private String passedParameter;

public UsersBean() {
    listOfUsers.add(new User("Tywin", "Lannister", 60, 1));
    listOfUsers.add(new User("Tyrion", "Lannister", 30, 2));
    listOfUsers.add(new User("Jaime", "Lannister", 31, 3));
    listOfUsers.add(new User("Cercei", "Lannister", 29, 4));
    listOfUsers.add(new User("John", "Snow", 31, 5));
}

public List<User> getAll() {

    System.out.println("getAall is called.");
    return listOfUsers;
}

public User getDetails() {
    passedParameter = (String) FacesContext.getCurrentInstance()
            .getExternalContext().getRequestParameterMap().get("userID");
    int id = Integer.parseInt(passedParameter);
    User selected = null;
    for (User u : listOfUsers) {
        if (u.getId() == id) {
            selected = u;
        }
    }
    return selected;
}

public String addUser(User u) {
    System.out.println("addUser is called.");
    if (u.getId() != 0) {
        for (User edit : listOfUsers) {
            if (edit.getId() == u.getId()) {
                System.out.println("Found it!");
                edit.setAge(u.getAge());
                edit.setName(u.getName());
                edit.setSurname(u.getSurname());
            }
        }

    } else {
        u.setId(listOfUsers.size() + 1);
        listOfUsers.add(u);
    }

    return "";
}
}

users.xhtml:

    <f:view>
        <!-- http://stackoverflow.com/questions/8083469/method-must-have-signature-string-method-etc-but-has-signature-void -->
        <h:dataTable value="#{usersBean.all}" var="u">

            <h:column>
                <f:facet name="header">
                    User ID
                </f:facet>
                    #{u.id}
            </h:column>

            <h:column>
                <f:facet name="header">
                    Name
                </f:facet>
                    #{u.name}
            </h:column> 

            <h:column>
                <f:facet name="header">
                    Details
                </f:facet>

                <h:link outcome="users" value="edit user">
                    <f:param name="userID" value="#{u.id}"></f:param>
                    <f:param name="action" value="edit"></f:param>
                </h:link>

                &nbsp;

                <h:link outcome="usersDetails" value="get details">
                    <f:param name="userID" value="#{u.id}"></f:param>
                </h:link>                   
            </h:column> 

        </h:dataTable>

        <h:panelGroup rendered="#{param['action'] == 'edit'}">
            <h1>Edit!</h1>
            <h:form>
                <ui:param name="editUser" value="#{usersBean.details}"></ui:param>
                <h:outputText value="Name"></h:outputText>
                <h:inputText value="#{editUser.name}"></h:inputText> <br />

                <h:outputText value="Surname"></h:outputText>
                <h:inputText value="#{editUser.surname}"></h:inputText> <br />

                <h:outputText value="Age"></h:outputText>
                <h:inputText value="#{editUser.age}"></h:inputText> <br />

                <h:commandButton action="#{usersBean.addUser(editUser)}" value="Edit" type="submit">    </h:commandButton>
            </h:form>
    </h:panelGroup>

        <h:panelGroup rendered="#{empty param['action']}">
            <h1>Add!</h1>
            <h:form>
                <h:outputText value="Name"></h:outputText>
                <h:inputText value="#{user.name}"></h:inputText>
                <h:outputText value="Surname"></h:outputText>
                <h:inputText value="#{user.surname}"></h:inputText>
                <h:outputText value="Age"></h:outputText>
                <h:inputText value="#{user.age}"></h:inputText>
                <h:commandButton action="#{usersBean.addUser(user)}" value="Add" type="submit"></h:commandButton>
            </h:form>
        </h:panelGroup>     

    </f:view>

好的，一切正常.usersBean.addUser 添加用户.如果我为 ID 添加另一个 inputText 并放入现有 ID，则相应的函数会更新值.因此，addUser 函数按预期工作.

OK, so, everything works perfectly. usersBean.addUser adds the user. If I add another inputText for ID and I put in an existing ID, the corresponding function updates the values. So, addUser function works as expected.

问题在于

<h:panelGroup rendered="#{param['action'] == 'edit'}">

正如你在上面的xhtml中看到的，代码基本相同，唯一的例外是我填写了被选中用户的数据.这有效，我将适当的数据放入输入字段，但是当我更改它们并单击编辑"时，没有任何反应.函数没有调用！而在 add 的情况下，该函数被调用并且它可以工作.似乎在编辑的情况下没有定义任何操作，它只会重新加载页面(提交)，而没有实际操作 addUser.

as you can see in the xhtml above, the code is basically the same, with the sole exception that I fill in the data of the user that was selected. This works, I get the appropriate data into input fields, but when I change them and click Edit, nothing happens. The function is not called! whereas in case of add, the function is called and it works. It appears as if there is no action defined in case of edit, it only reloads the page (submit) without the actual action addUser.

这是怎么引起的，我该如何解决?

How is this caused and how can I solve it?

推荐答案

这是因为 #{param['action'] == 'edit'} 没有评估 true 在处理表单提交期间，因此在处理表单提交期间基本上不会被渲染，包括坐在那里.表单提交即没有将该参数传递回 JSF.这样 JSF 就不会看到 <h:commandButton> ，因此永远无法解码和排队它的动作事件.您需要确保所有 rendered 条件在处理表单提交期间评估与显示表单期间相同(这是 JSF 防止篡改/黑客请求的一部分，否则最终用户将能够执行未渲染的命令按钮，如管理员专用按钮).

It's because #{param['action'] == 'edit'} didn't evaluate true during processing the form submit and therefore the <h:panelGroup> is basically not rendered during processing the form submit, including the <h:commandButton> sitting in there. The form submit namely did not pass that parameter back to JSF. This way JSF won't see the <h:commandButton> and therefore never be able to decode and queue its action event. You need to make sure that all your rendered conditions evaluate the same during processing the form submit as they were during displaying the form (this is part of JSF's safeguard against tampered/hacked requests wherein the enduser would otherwise be able to execute unrendered command buttons like admin-only buttons).

因此，您基本上也需要在回发期间保留该参数，以便 rendered 表达式在处理表单提交期间仍然评估 true.这可以通过多种方式实现:

So, you basically need to retain that parameter during the postbacks as well so that the rendered expression still evaluates true during processing the form submit. This can be achieved in several ways:

在相关的中添加:

<h:commandButton action="#{usersBean.addUser(editUser)}" value="Edit" type="submit">
    <f:param name="action" value="#{param.action}" />
</h:commandButton>

(注意:param['action'] 和 param.action 是等价的；这些括号仅在 'action' 包含句点，或代表另一个变量)

(note: param['action'] and param.action are equivalent; those brackets are only useful if the 'action' contains periods, or represents another variable)

通过将其设置为 bean 属性.要求是 bean 需要在视图范围内或更广泛的范围内.你已经在会话范围内了，这没关系(但这是 IMO太宽泛了，但除此之外):

Set it as a bean property by <f:viewParam>. Requirement is that the bean needs to be in view scope or broader. You've it in the session scope already, which is okay (but which is IMO way too broad, but that aside):

<f:metadata>
    <f:viewParam name="action" value="#{usersBean.action}" />
</f:metadata>
...
<h:panelGroup rendered="#{usersBean.action}">
    ...
</h:panelGroup>

如果您已经在使用 JSF 实用程序库 OmniFaces，请使用其 <o:form> 而不是，它使您能够提交到当前的请求 URI 而不是当前的 JSF 视图 ID.这样 GET 请求字符串将自动保留，您无需像 #1 一样在所有命令按钮上复制粘贴 <f:param>:

If you're already using JSF utility library OmniFaces, use its <o:form> instead of <h:form> which enables you submit to the current request URI instead of to the current JSF view ID. This way the GET request string will automagically be retained and you don't need to copypaste <f:param> over all command buttons like as in #1:

<o:form useRequestURI="true">
    ...
</o:form>

另见:

commandButton/commandLink/ajax action/listener 方法未调用或输入值未设置/更新 - 第 6 点

h:commandButton 一旦我将它包装在一个 <h:panelGroup 渲染> 中就不起作用了. [英] h:commandButton is not working once I wrap it in a <h:panelGroup rendered>

问题描述

推荐答案

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h:commandButton 一旦我将它包装在一个 &lt;h:panelGroup 渲染&gt; 中就不起作用了. [英] h:commandButton is not working once I wrap it in a &lt;h:panelGroup rendered&gt;

问题描述

推荐答案

另见:

See also:

相关文章

其他开发最新文章

热门教程

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h:commandButton 一旦我将它包装在一个 <h:panelGroup 渲染> 中就不起作用了. [英] h:commandButton is not working once I wrap it in a <h:panelGroup rendered>

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