how to call javascript function from managed bean?

Question

I have if condition in managed bean. I want to display alert when condition is true. How I do that? something like:

    public void catInsert()
        {
            if(abr.searchCategoryByCategoryName(CategoryName)!=null){
    //                msg = "<div style = 'color:red'>CategoryName already exist!</div>";
    //                System.out.println(msg);
//  i want alert here

            }else
            {
            abr.addCategory(CategoryName);
            CategoryName="";
            }
         }

and xhtml page is;

<table class="nostyle">
                <tr>
                    <td align="right">
                    <h:outputText value="Category Name:"></h:outputText>
                    </td>
                    <td>
                        <h:inputText id="txtcatname" value="#{categoryBean.categoryName}" required="true" requiredMessage="Enter category Name" >
                        </h:inputText>
                    </td>
                    <td ><h:message for="txtcatname" style="color: #df0000"></h:message></td>>            
                </tr>
                <tr>
                    <td></td>
                    <td align="left">
                        <h:commandButton id="submit" type="Submit" value="submit" action="#{categoryBean.catInsert()}" >
                        </h:commandButton>
                    </td>

                </tr>
            </table>

What's the problem with that? Where is your actual condition ? — Sarfraz, Jun 16 '12 at 09:30

score 2 · Answer 1 · answered Jun 16 '12 at 13:32

You're making a conceptual mistake. HTML/JS code doesn't belong in the controller, but in the view. The controller has to inform the view somehow that it has to generate the desired bunch of HTML/JS code.

You could do that by setting a boolean property like so

private boolean showCategoryNameAlert;

public void catInsert() {
    if (abr.searchCategoryByCategoryName(categoryName) != null) {
        showCategoryNameAlert = true;
    } else {
        abr.addCategory(categoryName);
    }
}

public boolean isShowCategoryNameAlert() {
    return showCategoryNameAlert;
}

with

<h:outputScript rendered="#{categoryBean.showCategoryNameAlert}">
    alert("CategoryName already exist!");
</h:outputScript>

By the way, why don't you use FacesContext#addMessage() with <h:messages> or maybe even a normal JSF Validator on the input field? Showing JavaScript alerts is soo 90's and performing input validation in an action method is poor design.

how to call javascript function from managed bean?

1 Answers1