4.12. Errors Reports

The Photo Album application has a global mechanism for errors checking. You become informed about the error each time it occurs. It is possible because the main page of the application web/src/main/webapp/index.xhtml includes the web/src/main/webapp/includes/misc/errorPanel.xhtml:


...

<a4j:outputPanel id="errors" ajaxRendered="true">

        <h:panelGroup rendered="#{errorHandlerBean.errorExist}">

            <rich:modalPanel id="errorPanel" showWhenRendered="true" minWidth="300" minHeight="200" autosized="true">

                      ...

            </rich:modalPanel>

      </h:panelGroup>

</a4j:outputPanel>

...

Here is the listing of the errorHandlerBean class:

package org.richfaces.photoalbum.ui;

import java.util.ArrayList;

import java.util.List;

import org.jboss.seam.ScopeType;

import org.jboss.seam.annotations.AutoCreate;

import org.jboss.seam.annotations.Name;

import org.jboss.seam.annotations.Observer;

import org.jboss.seam.annotations.Scope;

import org.richfaces.photoalbum.service.Constants;


@Name("errorHandlerBean")

@Scope(ScopeType.EVENT)

@AutoCreate

public class ErrorHandlerBean {

    private List<String> errors = new ArrayList<String>();


    public List<String> getErrors() {

        return errors;

    }

    

    public boolean isErrorExist(){

        return errors.size() > 0 ;

    }

    

    @Observer(Constants.ADD_ERROR_EVENT)

    public void addToErrors(String e){

        errors.add(e);

    }

}

The error panel contains the <a4j:outputPanel> component that is rendered on every Ajax request (ajaxRendered="true"). If an error is occurred the isErrorExist() method of errorHandlerBean class returns "true", so the <h:panelGroup> component is rendered. In order to show nested <rich:modalPanel> component with the collected errors the "showWhenRendered" attribute should be set to "true".

The addToErrors() method is annotated with @Observer annotation, thus it observes all events with ADD_ERROR_EVENT constant and adds errors to the errors List.

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4.12. Errors Reports