how to set values on the params attribute in export:formats element for grails export plugin

I have installed the grails export plugin. It has an element export:formats which takes a params value as attribute. I want to know how to set values from other elements onto this params attribute so that it is available to my controller action.

<div id="exportDetail">
     <g:select name="reportType" from="${['Daily', 'Weekly Hour', 'Weekly Day']}" ></g:select><br/>
     <g:datePicker name="reportStartDate" precision="hour"></g:datePicker><br/>
     <g:datePicker name="reportEndDate" precision="hour"></g:datePicker><br/>
     <export:formats action="exportRollup" formats="['csv', 'excel', 'ods', 'pdf', 'rtf', 'xml']" params="[**how to pass select, datepicker stuff here to controller**]"/>
</div>

Solution

The params you give to the taglib will only affect the link rendered by Grails. If you want the link to contain params that change after page rendering, such as the values selected by the datepickers, then you need to use Javascript. Here's a rough example:

 $('.menuButton a').click(function() {
     var target = this.href + '&reportStartDate=' + $('#reportStartDate').val();
     window.location.href = target;
     return false;
 });

Ideally, your export buttons would submit a form containing the datepickers, and you would not need to use Javascript. You would have to write your own formats taglib to do that. This'll get you started:

Create a new taglib in your project. Give it namespace = 'export', so it can override the plugin's tags. Copy the formats tag from ExportTagLib to your new taglib.
Change the <a> tag to a submit button: input(type: 'submit', name: 'format', value: format)
If you want graphic buttons, use this instead: input(type: 'image', name: 'format', value: format, src: g.resource(plugin: 'export', dir: 'images/skin', file: format + '.png'))
You'll now need a <form> tag around your <export:formats> tag in your GSP.

You won't be able to use params.extension in your controller anymore, but it's not hard to figure out the file extension from the format.