On the product page, we used a simple form to display an Add to comparison list button. We used the ProductListHandler.addProduct
method to add the product the user is viewing to a list of products to compare.
![](media/image44.png)
The Product page includes a section for adding items to and viewing the comparison list.
A View comparison list link is displayed on the page if there are products in the comparison list. Once a user adds a product to the list, the button is changed to display Remove from list and to use the ProductListHandler.removeProduct
method so that the product can be removed from the list.
![](media/image45.png)
When a product is on the comparison list, the button changes to display “Remove from list.”
Below is the code we used to implement the Product Comparisons section on the product page.
<dsp:form action="product.jsp" method="post"> <tr> <td bgcolor="#E5E5E5"> <input name="id" type="hidden" value="<dsp:valueof param="element.repositoryId"/>"> <dsp:input bean="CartModifierFormHandler.SessionExpirationURL" type="hidden" value="../common/session_expired.jsp"/> <dsp:input bean="CartModifierFormHandler.productId" paramvalue="product.repositoryId" type="hidden"/> <dsp:droplet name="ProductListContains"> <dsp:param bean="ProductList" name="productList"/> <dsp:param name="productID" param="element.repositoryId"/> <dsp:oparam name="true"> <dsp:input bean="ProductListHandler.productID" paramvalue="productID" type="hidden"/> <dsp:input bean="ProductListHandler.removeProduct" type="submit" value="Remove from list"/> </dsp:oparam> <dsp:oparam name="false"> <dsp:input bean="ProductListHandler.productID" paramvalue="productID" type="hidden"/> <dsp:input bean="ProductListHandler.addProduct" type="submit" value="Add to comparison list"/> </dsp:oparam> </dsp:droplet> </td> </tr> <!--check to see if there are items in comparison list--> <dsp:droplet name="IsEmpty"> <dsp:param bean="ProductList.items" name="value"/> <dsp:oparam name="false"> <tr> <td><span class=smallb><dsp:a href="compare.jsp">View comparison list</dsp:a></td> </tr> </dsp:oparam> </dsp:droplet> </dsp:form>