org.apache.wicket.ajax
Interface IAjaxRegionMarkupIdProvider

public interface IAjaxRegionMarkupIdProvider

A mixin that allows behaviors and components to override the id of the markup region that will be updated via ajax. If this mixin is not used then Component.getMarkupId() is used.

This mixin is useful when behaviors write directly to the response. Lets examine a simple behavior that wraps the component in a paragraph tag:

 class PB extends AbstractBehavior
 {
        public void onBeforeRender(Component c)
        {
                c.getResponse().write("<p>");
        }
 
        public void onComponentRendered(Component c)
        {
                c.getResponse().write("</p>");
        }
 }
 

If we add this behavior to a TextField the generated markup will be:

 <p><input wicket:id="name" type="text"></p>
 

If we then update this TextField via ajax the generated markup will erroneously be:

 <p><p><input wicket:id="name" type="text"></p></p>
 

Notice the doubling of the <p> tags. This is happening because every ajax render the input field is replaced with the markup that contains the input field surrounded by paragraph tags. To fix this we can modify our behavior as follows:

 class PB extends AbstractBehavior implements IAjaxRegionMarkupIdProvider
 {
        public void onBeforeRender(Component c)
        {
                c.getResponse().write("<p id='" + c.getMarkupId() + "_p'>");
        }
 
        public void onComponentRendered(Component c)
        {
                c.getResponse().write("</p>");
        }
 
        public String getAjaxRegionMarkupId(Component component)
        {
                return component.getMarkupId() + "_p";
        }
 }
 

Now, the ajax update will properly replace the markup region that includes the paragraph tags with the generated markup.

In the rare case that Component needs to implement this interface the component argument of the getAjaxRegionMarkupId(Component) method can be safely ignored because it will be the component itself.

Author:

Igor Vaynberg (ivaynberg)

Method Summary

String

getAjaxRegionMarkupId(Component component)

Method Detail

getAjaxRegionMarkupId

String getAjaxRegionMarkupId(Component component)