Why to add process="@this" explicitly to p:commandButton to get action invoked?

Srikanth Ganji picture Srikanth Ganji · Mar 6, 2014 · Viewed 32.9k times · Source

I know that we need to add explicitly process="@this" to get the p:commandbutton action get invoked and I also know that process attribute defaults to @form in primefaces.

Since process is defaulted to @form shouldn't the button also get processed along with the other elements in the form and its action should get invoked.

Can anyone explain the exact reason behind this?

Answer

Zaw Than oo picture Zaw Than oo · Jul 29, 2014

Process @form mean the current form of the commandLink/Button
Process @this mean the current component of the commandLink/Button. Check below code.

process.xhtml

<h:form id="form1">
    <h:inputText value="#{ProcessBean.id}" id="id"/><br/>
    <h:panelGroup id="panel_1">
        <h:inputText value="#{ProcessBean.name}" id="name"/><br/>
    </h:panelGroup>
    <h:panelGroup id="panel_2">
        <h:inputText value="#{ProcessBean.address}"/>
        <br/>
        <p:commandButton process="@form" value="Btm1" id="button1" action="#{ProcessBean.show}"/><!-- Default -->
        <p:commandButton process="@this" value="Btm2" id="button2" action="#{ProcessBean.show}"/>
        <p:commandButton process="@this form1:panel_1" value="Btm3" id="button3" action="#{ProcessBean.show}"/>
    </h:panelGroup>
</h:form>  

ProcessBean.java

@ManagedBean(name = "ProcessBean")
public class ProcessBean {
    private String id;
    private String name;
    private String address;
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }

    public void show() {
        System.out.println(id);
        System.out.println(name);
        System.out.println(address);
    }
}

Let's user input inputbox

001     -> id
Jone    -> name
London  -> address

Click button1, all JSF component(Eg : id, name, address) entire of the form will be process. Output will be :

001
Jone
London

Click button2, The process will be itself (Eg : button2). No process for id, name, address. Output will be:

null
null
null

Click button3, all JSF component(Eg : name) entire of the panel_1 and button3 will be process. Output will be :

null
Jone
null

Does not invoke your action method? There might be validation or conversion failed before invoke.