Try to use dynamic URL parameter with Web Application Designer

Hi Gurus,

I have BW 3.x and I would like to use "premise template".

In my dream this solution is the next:

A Web Application Designer template starts and contains some drop-down boxes to select data. After that the user press a button or click on a link and this template call another template which contains the result table. I would like to sent filter data in URL parameter, but I cannot solve this problem.

The static code is the following and it's ok:

href="<SAP_BW_URL cmd='LDOC' TEMPLATE_ID='TEMPLATE NAME' FILTER_IOBJNM='INFOOBJECT NAME' FILTER_VALUE='INFOOBJECT VALUE'>"

But how can I used the value of dropdownboxes?

Thanks for your helps