JSTL Change the order in which children tags are processed

Question

Hi there,
Is there any way one can manipulate the order in which tags are executed/processed within for example an iteration tag? I.e. let's say I have the following:
<m:my_iterate_tag data="data">
  <dotag1>XX</dotag1>
  <dotag2>YY</dotag2>
</m:my_iterate_tag/>The user can set as a preference in my application that they want <dotag2> to
be displayed/executed first before <dotag1>, e.g. like in a column in a table. How can I change
the order of these tags when I execute the <m:my_iterate_tag>? Do I do it in
<m:my_iterate_tag> or is there another or better way? Please help.
Thanks,
Marius Botha

Answer 1

Okay, lets start with getting the order in which to display columns... So you say:
get the order of these columns from the db (e.g. client
says 1=title, 2=number, don't display "type" column)Based on the DB, then, create a java.util.List that would have the column names in the order they want... (not real code...)
ArrayList columnOrder = ["title", "number"]
When you get to iter_tag:table.doStartBody, then create a java.util.HashMap (lets say) called tableColumnData.
Then in the iter_tag:column tag, you would the value provided in the tag mapped to the property name as the key in the tableColumnData map:
tableColumnData.put("number", <this iteration's number value>);
tableColumnData.put("title", <the value returned from the g:href tag>);
tableColumnData.put("type", <anything>);
Then, in the iter_tag:table.doEndBody, you do a loop, getting the name of the column to display from the columnOrder list, and using that name to pull the value out of the tableColumnData map:
    for (int i = 0; i < columnOrder.size(); i++) {
        out.println("<td>" + tableColumnData.get(columnOrder.get(i)) + "</td>");
    }You would put the columnOrder in a scope where you won't have to relaod it all the time, like maybe the user's session. You would put the tableColumnDataMap to make sure it is unique to the table... either in the pageContext, or store it in the iter_tag and make a method where the nested tags can retrieve it.