在Java Server Faces中使用带有CommandButton的托管属性 [英] Using managed-property with CommandButton in Java Server Faces

问题描述

除了我的问题在带有Facelets的Java Server Faces中创建编辑我的项目页面我会帮助解决这个问题。

In addition to my question "Creating an "Edit my Item"-page in Java Server Faces with Facelets" I would liek to cover an issue that this provided.

我按下commandButton，ID = 100被删除，页面刷新，这是之前它甚至运行方法，对，这意味着当我按下按钮时我没有ID 。

When I press the commandButton the ID=100 is removed and the page is refreshed, and this is Before it even runs the method, right, so this means that I do not have the ID when i press the button.

你如何解决这个问题？

拥有这个Managed Bean

By having this Managed Bean

public class BeanWithId implements Serializable {
  private String id;
  private String info;

  private void populateInfo() {
    info = "Some info from data source for id=" + id;
  }

  public String getId() { return id; }

  public void setId(String id) {
    this.id = id;
    populateInfo();
  }

  public String getInfo() { return info; }
  public void setInfo(String info) { this.info = info; }

  public String save() {
    System.out.println("Saving changes to persistence store");
    return null; // no navigation
  }
}

并添加

<p><h:commandButton action="#{beanWithId.save}" value="Save" /></p>

到我的facelet页面。现在我在faces-config.xml中也有正确的信息，当我使用？ID = 100访问我的页面时，我确实得到了正确的项目。

To my facelet-page. Now I also have the correct information in my faces-config.xml and when I access my page using ?ID=100 I do get the correct Item returned.

推荐答案

有几种方法可以保留原始GET URL的ID。我并不是想要全面。

There are several ways to preserve the ID from the original GET URL. I'm not attempting to be comprehensive.

向 commandLink 添加一个参数

Add a param to a commandLink

<h:commandLink action="#{beanWithId.save}" value="Save">
  <f:param name="ID" value="#{param.ID}" />
</h:commandLink>

每次点击链接时，ID都将从参数设置。

Any time the link is clicked, the ID will be set from parameter.

使用隐藏字段

<h:form>
  <h:inputHidden value="#{beanWithId.id}" />
  <p>ID: <h:outputText value="#{beanWithId.id}" /></p>
  <p>Info: <h:inputText value="#{beanWithId.info}" /></p>
  <p><h:commandButton action="#{beanWithId.save}" value="Save" /></p>
</h:form>

任何时候发布表格，都会从表格中设置ID。

Any time the form is posted, the ID will be set from the form.

保留网址

由于表单网址不包含原始查询，帖子将从浏览器栏中的URL中删除ID。执行操作后，可以通过使用服务器端重定向来解决此问题。

Since the form URL does not include the original query, a post will remove the ID from the URL in the browser bar. This can be rectified by use of a server-side redirect after the action has been performed.

  public String save() {
    System.out.println("Saving changes to persistence store: id=" + id);
    redirect();
    return null; // no navigation
  }

  private void redirect() {
    FacesContext context = FacesContext.getCurrentInstance();
    ExternalContext ext = context.getExternalContext();
    UIViewRoot view = context.getViewRoot();
    String actionUrl = context.getApplication().getViewHandler().getActionURL(
        context, view.getViewId());
    try {
      // TODO encode id value
      actionUrl = ext.encodeActionURL(actionUrl + "?ID=" + id);
      ext.redirect(actionUrl);
    } catch (IOException e) {
      throw new FacesException(e);
    }
  }

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