betweenGo

la cuarta ventana by bachmont 

Sometimes when you click on a link in an ATG JSP/DSP page you want a property of an ATG component to be set as well.  For example:

<dsp:a href="foo.jsp">Foo
  <dsp:property bean="BarFormHandler.baz" paramvalue="index"/>
</dsp:a>

What gets tricky is if you also want a popup window to display the contents of this link.

The Wrong Way

I tried adapting the instructions from the tutorial Popup Windows | open new customised windows with JavaScript.

<dsp:a href="javascript:poptastic('foo.jsp');">Foo
  <dsp:property bean="BarFormHandler.baz" paramvalue="index"/>
</dsp:a>

This does not work, i.e. the setter for baz in BarFormHandler is never called.

The Brute Force Way

I then reverted to the original DSP and looked at the outputted HTML.  Based on that I updated the DSP like this.

<% atg.servlet.DynamoHttpServletRequest dreq = atg.servlet.ServletUtil.getCurrentRequest(); %>
<a href="javascript:poptastic('foo.jsp?_DARGS=/betweengo/test.jsp_AF&_dynSessConf=<%= dreq.getSessionConfirmationNumber() %>&_D%3A/betweengo/BarFormHandler.baz=+&/betweengo/BarFormHandler.baz=<dsp:valueof param="index" />');">Foo</a>

This works but is grotesque.

The Good Idea That Did Not Work

Then I realized I could just set a parameter in the URL and have the form handler use the value to set the property.

<a href="javascript:poptastic('foo.jsp?index=<dsp:valueof param="index" />');">Foo</a>

And in BarFormHandler

public boolean beforeSet(DynamoHttpServletRequest req,
            DynamoHttpServletResponse res) throws DropletFormException {

  String indexParam = request.getParameter("index");
  setIndex(Integer.parseInt(indexParam));

  return super.beforeSet(request, response);
}

This did not work plus I did not really like it because now I have a beforeSet method that is called for every single request.

The Winner

I then realized I did not read the tutorial Popup Windows | open new customised windows with JavaScript carefully.  There is a more elegant way to call the JavaScript which degrades gracefully for browsers that don’t support JavaScript.

<dsp:a href="foo.jsp" onclick="poptastic(this.href);return false;">Foo
  <dsp:property bean="BarFormHandler.baz" paramvalue="index"/>
</dsp:a>

This works, is elegant and requires just adding the onclick attribute to the original DSP.

(Photo: Leaf on my car by exfordy)

The ATG Date Tag Converter is buggy because Java’s DateFormat is inherently unsafe for multithreaded use.  This is documented in ATG PR #123210 DateTagConverter.convertObjectToString() method is not thread safe.

You run into this problem whenever you do something like this.

<dsp:valueof param=”creationDate” converter=”date” date=”M/dd/yyyy”/>

Unfortunately there is no work around.  If using the Date Tag Converter is not causing problems for you, i.e you don’t see a stack trace like below, then you can ignore this bug.

2009-04-17 00:19:08,220 ERROR [nucleusNamespace.atg.dynamo.servlet.dafpipeline.DynamoServlet] java.lang.ArrayIndexOutOfBoundsException: 502
  at sun.util.calendar.BaseCalendar.getCalendarDateFromFixedDate(BaseCalendar.java:436)
  at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:2081)
  at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:1996)
  at java.util.Calendar.setTimeInMillis(Calendar.java:1071)
  at java.util.Calendar.setTime(Calendar.java:1037)
  at java.text.SimpleDateFormat.format(SimpleDateFormat.java:785)
  at java.text.SimpleDateFormat.format(SimpleDateFormat.java:778)
  at java.text.DateFormat.format(DateFormat.java:314)
  at atg.droplet.DateTagConverter.convertObjectToString(DateTagConverter.java:176)

But if you do see a bug like this then you might need to create a custom droplet to format the date.  The droplet should only use DateFormat instances that are not static.  I usually make my DateFormat instances local.

 
(Photo: Escalera al cielo / Stairway to heaven by Davichi)

When I create a DSP textarea tag like this it outputs the value of the bean property in the text area box.

<dsp:textarea bean="MyFormHandler.foo" rows="5" cols="20"/>

Similarly if I create a DSP textarea tag like this I get the same output.

<dsp:textarea bean="MyFormHandler.foo" rows="5" cols="20"></dsp:textarea>

However when I leave some space between the textarea opening and closing tag I get a blank instead of the value of the bean property in the text area box.

<dsp:textarea bean="MyFormHandler.foo" rows="5" cols="20">
</dsp:textarea>

Anyone know why there is a difference?

Anyway after reading the documentation it turns out if I want to control what is output in the text box I can use the default attribute.

<dsp:textarea bean="MyFormHandler.foo" rows="5" cols="20" default="bar"/>

Maybe I should have read the documentation before writing this post.

Update 2009-09-03: I also found this strange pattern of behavior with the DSP droplet tag.  When I invoked a droplet that took no parameters and had no open parameters like this:

<dsp:droplet name="MyDroplet"/>

or like this:

<dsp:droplet name="MyDroplet"></dsp:droplet>

the droplet would not be invoked.

However when I did this the droplet was invoked.  Strange …

<dsp:droplet name="MyDroplet">
</dsp:droplet>

This JSP code was not outputting the properly formatted amount.

<dspel:valueof value="${dollars}" converter="currency" />

I tried forcing it by specifying the conversion parameters.

<dspel:valueof value="${dollars}" converter="currency" locale="en-CA" format="#.00" currency="$" />

I then debugged atg.droplet.CurrencyTagConverter using Eclipse and found this code being executed.

public String convertObjectToString(DynamoHttpServletRequest pRequest,
                                 Object pValue, Properties pAttributes)
  throws TagConversionException
{
  if ((pValue == null) || (pValue instanceof String))
    return (String)pValue;

It turns out pValue was a String which is why it was never being formatted.  But why is it a String?

Well the code that sets dollars looks like this.

<dspel:tomap var="paymentGroup" param="commerceItem.paymentGroups[1]" />
<c:set var="dollars" value="0" />
<c:if test="${not empty paymentGroup}">
  <c:set var="dollars" value="${paymentGroup.amount}" />
</c:if>

Apparently c:set converts the Double to a String.

To work around this problem I did this.

$<dspel:valueof number="0.00" value="${dollars}" />

For further reading please see Tag Converters in the ATG Page Developer’s Guide.

Today I added a feature in my shopping cart JSP page but nothing was showing up.  This was because the output of ATG ForEach droplet was blanks.

To debug this I did the following steps.

1. I added an empty oparam to see if the ForEach droplet thought the collection was empty.

   <dsp:oparam="empty">Empty?</dsp:oparam>

   It did not.

2. I outputted the count in the output oparam to see if it was looping through the collection.

   <dsp:oparam="output"><dsp:valueof param="count"/> <dsp:valueof param="element"/></dsp:oparam>

   It was looping through the collection.

3. Finally I debugged using Eclipse the ForEach code.  The ForEach code can be found in <ATG>/DAS/src/Java/atg/droplet/ForEach.java. 

   Using the debugger I realized that the element name of the loop was being set to something else which is why <dsp:valueof param=”element”/> was blank.

It turned out that the ForEach droplet was inside another ForEach droplet and in that droplet they set the element name like this.

<dsp:param name="elementName" value="CommerceItem" />

By setting the elementName parameter to something else in my ForEach droplet and then referencing it properly I was finally able to get the expected output.

<dsp:droplet name="/atg/dynamo/droplet/ForEach">
 <dsp:param name="array" param="CommerceItem.auxiliaryData.productRef.dvds"/>
 <dsp:param name="elementName" value="dvd" />
 <dsp:oparam name="output">
  <dsp:valueof param="dvd.name" />
 </dsp:oparam>
</dsp:droplet>

By the way ATG documentation suggests not using elementName.

elementName and indexName allow you to provide a parameter name other than element and index, respectively. A better way to provide a different parameter name is to use the dsp:setvalue tag.

In our example we would do this instead of setting the elementName param.

 <dsp:setvalue param="dvd" paramvalue="element" />

Sometimes you want to list each item in the collection with a separator in between like a comma or slash.  However the trick is to have the separator only in between items.

In ATG DSP you can use the ForEach droplet to iterate through each item in a collection.  However to put a separator between each item is not straight-forward with this droplet.  To do this I used JSTL to test if we are at the end of the collection.  If we are then I don’t add the separator, otherwise I do.

Here is an example.

<dspel:droplet name="/atg/dynamo/droplet/ForEach">
 <dspel:param name="array" param="dvds"/>
 <dspel:setvalue param="dvd" paramvalue="element" />
 <dspel:oparam name="outputStart">
  <dspel:getvalueof var="size" param="size" />
 </dspel:oparam>
 <dspel:oparam name="output">
  <dspel:valueof param="dvd.title" valueishtml="true"/>
  <dspel:getvalueof var="count" param="count" />
  <c:if test="${size != count}"> , </c:if>
 </dspel:oparam>
</dspel:droplet>

And here is the output for this example.

The Incredibles, Ratatouille, Cars

Do you have a better or more elegant solution?  Please feel free to let me know in the comments?

I always forget how to do this so I thought I should write it down.

In JSP:

<%=request.getParameter("foo")%>
<img src="<%=request.getParameter("foo")%>">

In JSTL:

<c:out value="${param.foo}"/>

In DSP:

<dspel:valueof param="foo"/>