Wrapping Component Contents - BloomReach Experience - Open Source CMS

This article covers a Hippo CMS version 10. There's an updated version available that covers our most recent release.

13-05-2015

Wrapping Component Contents

An HST Component can set a wrapper element for its rendered content to make it easy to refer the content markup elements from client-side technologies such as JavaScript.

An HST Component can simply invoke HstResponse#setWrapperElement(Element) to set its wrapper element or its rendering template JSP or Freemarker template page could contain <hst:wrapperElement /> tag to do the same thing as HstResponse#setWrapperElement(Element)invocation.

What do you do when you need to handle some markup contents of HST Component(s) from the client-side?

Suppose your component renders the following:

<h1>Always Look on the Bright Side of Life (from Monty Python)</h1>

<p>Some things in life are bad. They can really make you mad. Other things just make you swear and curse. When you're chewing on life's gristle. Don't grumble, give a whistle. And this'll help things turn out for the best...<p>

If you want to refer the rendered markup contents above, you can wrap the contents in your template (JSP or freemarker) page as follows:

<span id="component1" class="wrapper">

<h1>Always Look on the Bright Side of Life (from Monty Python)</h1>

<p>Some things in life are bad. They can really make you mad. Other things just make you swear and curse. When you're chewing on life's gristle. Don't grumble, give a whistle. And this'll help things turn out for the best...<p>

</span>

So, now you can use DOM accesses or CSS Selector to refer the contents because all rendered markups are now wrapped by a span with id and css attributes.

Obviously, you do not want to add the wrapper elements manually in every JSP/freemarker template. You can do this as follows:

HstResponse interface provides the following methods:

import org.w3c.dom.Element;

public void setWrapperElement(Element element);
public Element getWrapperElement();

If you want to wrap the rendered markups of a component, you can simply set a wrapper element for the component by using HstResponse#setWrapperElement(Element);

For example, if you want to wrap every component markup content, then you could add the following codes into the #doBeforeRender() method of the base component class:

// BaseComponent.java

public void doBeforeRender(HstRequest request, HstResponse) throws HstComponentException {
    // ...
    // Sets wrapper element for each component
    Element wrapperElem = response.createElement("span");
    wrapperElem.setAttribute("class", "wrapper");
    response.setWrapperElement(wrapperElem);
    // ...
}

If your component extends the base component class above with super.doBeforeRender(...), then your component will be rendered with a wrapper element you specified in the base component even though you don't modify each template page manually.

One more minor tip is that you can set a wrapper element in the template page by using a tag library if you want:

< hst:element var="wrapperElem" name="span">

< hst:attribute name="id" value="component1" />

< hst:attribute name="class" value="wrapper" />

</ hst:element>

< hst:setWrapperElement element="${wrapperElem}" />

In Freemarker template, you can use the tag like the following:

<@ hst.element var="wrapperElem" name="span">

<@ hst.attribute name="id" value="component1" />

<@ hst.attribute name="class" value="wrapper" />

</@ hst.element>

<@ hst.setWrapperElement elementByBeanPath="wrapperElem" />

The tag library usage above is just invoking HstResponse#setWrapperElement(Element) operation. So, you can choose either approach. Because the render page template is invoked after doBeforeRender() of a component, this tag library usage could be regarded as overriding the wrapper element by re-invoking HstResponse#setWrapperElement(Element) method.

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