Validation of ViewParam and a4j:commandButton

问题

I think i came across a bug of @ViewScoped with a4j:commandButton.

I have a very complex form where all actions use a4j, except those that need to upload data. And depending on the order of the commands the validation of the viewParam breaks.

Here is the working code:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:a4j="http://richfaces.org/a4j" >

  <f:metadata>
    <f:viewParam id="viewParam" name="viewParam" value="#{bean.viewParam}" required="true" />
  </f:metadata>
  <h:head>
    <title>Test View Param</title>
  </h:head>
  <h:body>
    <h:message for="viewParam" />
    <hr/>
    <h:form>
      #{bean.viewParam}<br/>
      <h:commandButton value="cmdButton" />
      <a4j:commandButton value="a4jBtn" execute="@this" render="@form" />
    </h:form>  
  </h:body>
</html>

just click on the a4jBtn and then on the cmdButton to see the problem. you will see that the parameter is still there! but that the validation fails.

<t:saveState> does not help, <rich:message> is also not better, but

<h:commandButton value="ajaxBtn" ><f:ajax execute="@this" render="@form" /></h:commandButton>

instead of

<a4j:commandButton value="a4jBtn" execute="@this" render="@form" />

does work correctly!

Using myFaces 2.0.15 and richFaces 4.2.3.Final on Tomcat 6.0.18 and jboss-el 2.0.0.GA.

i could workaround my problem by using f:ajax instead of a4j:commandButton, but maybe you have a better idea, or you could just explain to me what is going wrong?

回答1:

You basically need to retain the view parameters on synchronous postbacks. As you're using OmniFaces, you could use <o:form> for that.

<o:form includeViewParams="true">

Or as you're already using a view scoped bean, trigger the validation only on non-postbacks.

<f:viewParam ... required="#{not facesContext.postback}" />

Or, as you're using OmniFaces, you could use <o:viewParam> instead which skips the validation/conversion/update on postbacks.

<o:viewParam ... />

来源：https://stackoverflow.com/questions/14194462/validation-of-viewparam-and-a4jcommandbutton

标签

jsf

ajax4jsf

commandbutton