JSF MethodExpression isn't triggering my backing bean action

Question 1

JSF MethodExpression isn't triggering my backing bean action

jsf methods uicomponents

Chris Dale · Mar 20, 2009 · Viewed 13.2k times · Source

Answer

Answer

I think the problem you encounter is due to the way you add the commandButton in the JSF component tree, or, to be more exact, the way uou do NOT add it in the component tree.

As you do not attach the commandButton to the JSF component tree, when this component is rendered (by your call to .encodeAll() method), it does not find the form where this component is nested. Thus, the HTML input is not created correctly.

Maybe you can try to add the commandButton created to the form directly, before asking it to be rendered. You can do that with the following code:

// Search for the component HtmlForm that is a (in)direct parent of the current component
private UIComponent getCurrentForm(UIComponent currentComponent) {
    UIComponent parent = currentComponent.getParent();
    while ((parent != null) && !(parent instanceof HtmlForm)) {
        parent = parent.getParent();
    }
    return parent;
}


public void encodeBegin(FacesContext context) throws IOException {
    ...
    HtmlAjaxCommandButton replyCommentButton = new HtmlAjaxCommandButton();
    ...

    // Add the command button in the form that contains your custom component...
    UIComponent form = getCurrentForm(this);
    if (form != null) {
        form.getChildren().add(replyCommentButton);
    }
    replyCommentButton.encodeAll(context);
    ...
}

note that I've tested this code, so maybe you have to modify it a little...

If it still doesn't work, maybe you will need to review you code in order to create the commandButton outside the render class or outside the encodeBegin... I don't think it is a good idea to modify the JSF components tree during the rendering phase...

Question 2

I have the problem that my code isn't triggering the action in my backing bean. The code is as follows:

HtmlCommandButton replyCommentButton = new HtmlCommandButton();
replyCommentButton.setId("replyCommentButton" + commentCounter);
replyCommentButton.setValue("Create reply");
String action = "#{Handler.action_replyToComment}";
MethodExpression methodExpression =  
FacesContext.getCurrentInstance().getApplication().getExpressionFactory().
createMethodExpression(FacesContext.getCurrentInstance().getELContext(), action, null,
new Class<?>[0]);
replyCommentButton.setActionExpression(methodExpression);

In my backing bean called RequestHandlerBean, defined in FacesConfig as Handler, I have the following code:

public void action_replyToComment() {
logger.info("Homemade action called!!!");
System.out.println("Homemade action called!!!");
}

Does anyone spot why nothing happens when I click the button? It isn't triggering the event properly. The source of the html code is as follows:

<input id="replyCommentButton1" type="submit" value="Create reply"   
name="replyCommentButton1"/>

As we can see there's no action defined in the HTML.

Edit 2: I just found out in Javadoc that my action method has to be a public String. I've changed this in my backing bean now so the code in my backing bean is:

public String action_replyToComment() {
logger.info("Homemade action called!!!");
System.out.println("Homemade action called!!!");
return null;
}

Edit2: I've also made sure that I have it encapsulated within a tag, but still no luck. Shouldn't there be a action attribute on the element?

Edit3: My bean is defined in my faces-config like this:

<managed-bean>
<description>
Handles the specific request.
</description>
<managed-bean-name>Handler</managed-bean-name>
<managed-bean-class>no.ngt.tech.rt2.beans.RequestHandlerBean</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>

Also if I choose to output in my JSF page like this:

<a4j:commandButton action="#{Handler.action_replyToComment}" value="Reply" />

That works perfectly

EDIT 4 - MY JSP PAGE Note Ive also tried using the depreciated setAction(methodBinding) now too, but sadly it didnt work either.

<%@ include file="_includes.jsp" %>
<f:view>
<html>
<head>
<title><h:outputText value="#{msgs.title}" /></title>
</head>
<body>
<br /><br /><br />



<%@ include file="_menu.jsp" %>

<rich:tabPanel switchType="client">

<rich:tab id="commentsTab" label="Comments" rendered="#{Handler.editRequest}">
<h:form>
         <ngt:commentTree binding="#{Handler.commentTree}" value="#{Handler.comments}"  />

         <br />

         <a4j:commandButton action="#{Handler.action_replyToComment}" value="testbutton" />
</h:form>    
</rich:tab>


</rich:tabPanel>

</body>
</html>
</f:view>

menu.jsp:

<h:form>
    <rich:toolBar itemSeparator="line" styleClass="toolbar" contentClass="toolbar" height="22">
        <rich:toolBarGroup>
            <rich:menuItem submitMode="server" value="Front" action="#{newRT.action_showFront}" />
        </rich:toolBarGroup>
        <rich:toolBarGroup>
            <rich:menuItem submitMode="server" value="New request" action="#{Step.action_showSteps}" />
        </rich:toolBarGroup>
        <rich:toolBarGroup>
            <rich:menuItem submitMode="server" value="Requests" action="#{Handler.action_showRequestsView}" />
        </rich:toolBarGroup>
        <rich:toolBarGroup>
            <rich:menuItem submitMode="server" value="Control-panel" action="#" />
        </rich:toolBarGroup>
        <rich:toolBarGroup location="right">
            <h:inputText styleClass="barsearch" value="#{Handler.search}" />
            <a4j:commandButton styleClass="barsearchbutton" action="#{Handler.action_GetRequestFromID}"  value="Search" />
        </rich:toolBarGroup>
    </rich:toolBar>
</h:form>


<br/><br/>

Includes.jsp

<%@ taglib prefix="h" uri="http://java.sun.com/jsf/html" %>
<%@ taglib prefix="f" uri="http://java.sun.com/jsf/core" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="a4j" uri="http://richfaces.org/a4j" %>
<%@ taglib prefix="rich" uri="http://richfaces.org/rich"%>
<%@ taglib prefix="ngt" uri="http://MySpecialTagLib.no/"%>

Edit 7 - Java code for UIComponent:

This is CommentsTreeUI.java:

public class CommentsTreeUI extends UIOutput {

    private static Logger logger = Logger.getLogger(CommentsTreeUI.class.getName());

    @Override
    public void encodeBegin(FacesContext context) throws IOException {

        List<CommentTag> value = (List<CommentTag>) getAttributes().get("value");
        int commentCounter = 0;

        if (value != null) {
            for (CommentTag comment : value) {
                commentCounter++;
                ResponseWriter commentContainerWriter = context.getResponseWriter();
                commentContainerWriter.startElement("div", this);
                commentContainerWriter.writeAttribute("id", "Comment" + commentCounter, null);

                String width = comment.getWidth();
                String height = comment.getHeight();

                String style = comment.getStyle();

                style = (style != null) ? style + ";" : "";

                if (width != null) {
                    style += "width:" + width + ";";
                }
                if (height != null) {
                    style += "height:" + height + ";";
                }

                commentContainerWriter.writeAttribute("style", style, null);

                String newComment = comment.getNewComment();
                if (newComment == null) {
                    newComment = "false";
                }

                String level = comment.getLevel();

                if (level != null) {
                    level = "commentContainerLevel" + level + newComment;
                }
                commentContainerWriter.writeAttribute("class", level, null);

                String title = comment.getTitle();
                if (title != null) {
                    commentContainerWriter.writeAttribute("title", title, null);
                }

                String titleText = comment.getTitleText();
                if (titleText != null) {
                    ResponseWriter titleTextWriter = context.getResponseWriter();
                    UIOutput titleTextComponent = new UIOutput();
                    titleTextWriter.startElement("div", titleTextComponent);
                    titleTextWriter.writeAttribute("class", "commentHeaderText" + newComment, null);
                    titleTextWriter.writeText(titleText + " | ", null);
                    titleTextWriter.startElement("a", titleTextComponent);
                    titleTextWriter.writeAttribute("onclick", "showCommentReply('CommentReply" + commentCounter + "')", null);
                    titleTextWriter.writeAttribute("class", "reply", null);
                    titleTextWriter.writeText("Reply", null);
                    titleTextWriter.endElement("a"); 
                    titleTextWriter.endElement("div");
                }

                String commentBody = comment.getCommentBody();
                if (commentBody != null) {
                    ResponseWriter commentBodyWriter = context.getResponseWriter();
                    UIOutput commentBodyComponent = new UIOutput();
                    commentBodyWriter.startElement("div", commentBodyComponent);
                    commentBodyWriter.writeText(commentBody, null);
                    commentBodyWriter.endElement("div");
                }

                ResponseWriter replyContainerWriter = context.getResponseWriter();
                UIOutput replyContainerComponent = new UIOutput();
                replyContainerWriter.startElement("div", replyContainerComponent);
                commentContainerWriter.writeAttribute("id", "CommentReply" + commentCounter, null);
                replyContainerWriter.writeAttribute("class", "replyContainer", null);

                ResponseWriter replyHeaderWriter = context.getResponseWriter();
                UIOutput replyHeaderComponent = new UIOutput();
                replyHeaderWriter.startElement("div", replyHeaderComponent);
                replyHeaderWriter.writeAttribute("class", "replyHeaderContainer", null);
                replyHeaderWriter.endElement("div");

                ResponseWriter replyFormWriter = context.getResponseWriter();
                UIInput replyFormComponent = new UIInput();
                replyFormWriter.startElement("fieldset", replyFormComponent);
                replyFormWriter.startElement("textarea", replyFormComponent);
                replyFormWriter.writeAttribute("type", "textarea", null);
                replyFormWriter.writeAttribute("rows", "5", null);
                replyFormWriter.writeAttribute("cols", "76", null);
                replyFormWriter.writeText("Write your answer here", null);
                replyFormWriter.endElement("textarea");


                //TODO: Fix so button has action to backing bean
                HtmlAjaxCommandButton replyCommentButton = new HtmlAjaxCommandButton();
                replyCommentButton.setId("replyCommentButton" + commentCounter);
                replyCommentButton.setValue("Create reply");
                String action = "#{RequestHandlerBean.action_replyToComment}";
                //replyCommentButton.setReRender("commentsTree");
                ExpressionFactory factory = context.getApplication().getExpressionFactory();
                Class [] argtypes=new Class[1];
                argtypes[0]=ActionEvent.class;

                MethodExpression replyActionExpression = factory.createMethodExpression(context.getELContext(), action, null, argtypes);
                replyCommentButton.setActionExpression(replyActionExpression);

                MethodExpression methodExpression = context.getCurrentInstance().getApplication().getExpressionFactory().
                        createMethodExpression(context.getCurrentInstance().getELContext(), action, null, new Class<?>[0]);
                replyCommentButton.setActionExpression(methodExpression);
                /*
                replyCommentButton.setAction(context.getApplication().createMethodBinding(action, argtypes));
                */

                replyCommentButton.encodeAll(context);
                //Todo above


                replyFormWriter.writeText(" ", null);
                replyFormWriter.startElement("input", replyFormComponent);
                replyFormWriter.writeAttribute("type", "button", null);
                replyFormWriter.writeAttribute("value", "Cancel ", null);
                replyFormWriter.writeAttribute("onclick", "hideCommentReply('CommentReply" + commentCounter + "')", title);
                replyFormWriter.endElement("input");
                replyFormWriter.endElement("fieldset");
                replyContainerWriter.endElement("div");
                commentContainerWriter.endElement("div");
            }
        } else { //value==null
            ResponseWriter writer = context.getResponseWriter();
            writer.startElement("div", this);

            writer.writeAttribute("id", getClientId(context), null);

            String width = (String) getAttributes().get("width");
            String height = (String) getAttributes().get("height");

            String style = (String) getAttributes().get("style");

            style = (style != null) ? style + ";" : "";

            if (width != null) {
                style += "width:" + width + ";";
            }
            if (height != null) {
                style += "height:" + height + ";";
            }

            writer.writeAttribute("style", style, null);

            String styleClass = (String) getAttributes().get("styleClass");
            if (styleClass != null) {
                writer.writeAttribute("class", styleClass, null);
            }

            String title = (String) getAttributes().get("title");
            if (title != null) {
                writer.writeAttribute("title", title, null);
            }

        }
    }

    @Override
    public void encodeEnd(FacesContext context) throws IOException {
        ResponseWriter writer = context.getResponseWriter();
        writer.endElement("div");
    }

This is CommenstTreeTag:

public class CommentsTreeTag extends UIComponentTag {

    String style;
    String styleClass;
    String title;
    String width;
    String height;
    String value;
    Long parentId;

    public void release() {
        // the super class method should be called
        super.release();
        style = null;
        styleClass = null;
        title = null;
        height = null;
        width = null;
        parentId = null;
        value = null;
    }

    @Override
    protected void setProperties(UIComponent component) {
        // the super class method should be called
        super.setProperties(component);

        if (style != null) {
            component.getAttributes().put("style", style);
        }

        if (styleClass != null) {
            component.getAttributes().put("styleClass", styleClass);
        }

        if (width != null) {
            component.getAttributes().put("width", width);
        }

        if (height != null) {
            component.getAttributes().put("height", height);
        }

        if (title != null) {
            if (isValueReference(title)) {
                ValueBinding vb =
                        getFacesContext().getApplication().createValueBinding(title);
                component.setValueBinding("title", vb);
            } else {
                component.getAttributes().put("title", title);
            }
        }
        if (value != null) {
            if (isValueReference(value)) {
                ValueBinding vb =
                        getFacesContext().getApplication().createValueBinding(value);
                component.setValueBinding("value", vb);
                getFacesContext().getApplication().createValueBinding(value);

            } else {
                component.getAttributes().put("value", value);
            }
        }
        if (parentId != null) {
            component.getAttributes().put("parentId", parentId);
        }
    }



    public String getComponentType() {
        return "commentTree";
    }

    public String getRendererType() {
        // null means the component renders itself
        return null;
    }

    public String getHeight() {
        return height;
    }

    public void setHeight(String height) {
        this.height = height;
    }

    public String getWidth() {
        return width;
    }

    public void setWidth(String width) {
        this.width = width;
    }

    public String getStyle() {
        return style;
    }

    public void setStyle(String style) {
        this.style = style;
    }

    public String getStyleClass() {
        return styleClass;
    }

    public void setStyleClass(String styleClass) {
        this.styleClass = styleClass;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }
}

JSF MethodExpression isn't triggering my backing bean action

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