Update the page with command bouton primefaces - html

Question

I want to get the value of the input Textarea and show it in the same page by clicking on the command button "compiler "
however i don't get any result ! and the contnet is only shown when I update with the browser updater
Sh How do I upate the page and the managed beans to show the content of a primefaces textarea in the same page
this is the code:
<p:layoutUnit position="west" size="520" header="Code à executer" resizable="true" >
<h:form id="moncode">
<p:inputTextarea id="mycode" value="#{fichier.code}" rows="17" cols="50" />
<p:commandButton value="compiler" id="btn3" action="guest.xhtml" styleClass="myButtonClass" />
</h:form>
</p:layoutUnit>
<p:layoutUnit position="east" size="550" header="Resultat d'execution" resizable="true" >
<h:outputText value="#{fichier.code}" />
</p:layoutUnit>
<p:layoutUnit position="south" >
my application is about compiling a given code: I write a code and then I executed with the button "compiler" so a file will be created however the file is always created with "null" and I think because the var "code" is not yet set in the managed bean that why I want to update the page so the managed bean ill be set here is compile:
`
private String code;
private String error;
public String getCode() {
return code;
}
public String getError() {
return error;
}
public void setCode(String code) {
this.code = code;
}
public void compile() throws IOException {
File file = new File("C:\\Users\\Rad1\\test.c");
PrintWriter ecrivain;
ecrivain = new PrintWriter(new BufferedWriter (new FileWriter(file)));
ecrivain.println(code);
ecrivain.close();
`

Answer 1

There are two ways to achieve what you want: either by using a synchronous submit of a form with a subsequesnt postback, or by sending an AJAX request to partially update necessary parts of the page.
Synchronous submit
<p:inputTextarea id="mycode" value="#{fichier.code}" rows="17" cols="50" />
<p:commandButton value="compiler" id="btn3" action="#{fichier.action}" styleClass="myButtonClass" ajax="false" />
<h:outputText id="upd" value="#{fichier.code}" />
with action method
public String action() {
//do business job
return null;
}
This way a fields will be refreshed by making a postback. Don't forget that the bean Fichier must be view scoped. Note the ajax="false" attribute of <p:commandButton>.
AJAX call
<p:inputTextarea id="mycode" value="#{fichier.code}" rows="17" cols="50" />
<p:commandButton value="compiler" id="btn3" action="#{fichier.action}" styleClass="myButtonClass" update="upd" />
<h:outputText id="upd" value="#{fichier.code}" />
with the same action method
public String action() {
//do business job
return null;
}
This way only the contents of <h:outputText> will be updated after AJAX call is finished. Don't forget that the bean Fichier should also be view scoped. Note that id attribute of <h:outputText> must be specified.

Answer 2

Actually, you don't call the action itself. Your action forwards to a certain page. There is no race condition or syncronization problems in a JSF action betwwen setting the properties and the action itself. I recommend you to read JSF life cycles tutorial by BalusC Aplly request values phase run before the action.
Try to call action on command Button.
<p:commandButton value="compiler" id="btn3" action="#{fichier.compile}" update="outputCode" styleClass="myButtonClass" />
Add an id attribute to your output panel and specify it in the action button.
<p:layoutUnit id="outputCode" position="east" size="550" header="Resultat d'execution" resizable="true" >
<h:outputText value="#{fichier.code}" />
</p:layoutUnit>
P.S. It is also good to read this BalusC answer for better understanding of actions, Ajax/non Ajax request etc.