Using managed-property with CommandButton in Java Server Faces

Question

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.

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.

How do you solve this?

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
  }
}

And adding

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

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.

Answer 1

You can set the property by using f:setPropertyActionListener if you use JSF 1.2 or newer.

<h:commandButton value="Save" action="#{beanWithId.save}">
     <f:setPropertyActionListener target="#{beanWithId.id}" value="100" />
</h:commandButton>

If you use JSF 1.1 or prior you can use

<f:param name="reqId" value="100" />

but this time you have to get the parameter and set it manually in the action like such:

public String save() {
String idParam
=FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("reqId");
setId(idParam);
return null;
}

Answer 2

This solved my problem

<h:commandLink action="#{beanWithId.save}" value="">
    <f:verbatim><input type="button" value="Save"/></f:verbatim>
    <f:param name="id" value="#{beanWithId.id}"/>
</h:commandLink>

Works like a Charm, it does however remove the visible GET-parameter, but it is still stored so that the faces-config can access param.id.

Answer 3

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

Add a param to a commandLink

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

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

Use a hidden field

<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>

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

---

Preserving the URL

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);
    }
  }