Change hidden form field value

Question

hi everyone...i'm hoping someone can help me figure out how
to change the value of a hidden field in a form. i have a page
setup where users pay a website fee. since the fee is always the
same, i have the amount setup in a hidden field in my form. my
question is, i'd like to use promo codes. so i'll add a box in my
form that says "enter promo code." then there's a link in the form
that says "apply promo code." i'm thinking that link needs to
refresh my page and take the value entered by the user in the promo
code form field and place it in the url. that way i can write a
cfif statement to change the value of the hidden field. the problem
is, i can't figure out how to "refresh" the page and take the value
out of the form field and place it in the url. hope this makes
sense. maybe someone can offer a better way to do this? i'd truly
appreciate any help anyone can offer. thanks!

Answer 1

You would change the amount on the processing page with
ColdFusion (after the form is submitted), but prior to the CFHTTP
call. You really should familiarize yourself with CFHTTP (check
online documentation). It sounds like it is exactly what you need.
The format of your application would be something like:
promocode.cfm:
====================
<form name="someform" method="post"
action="process.cfm">
<input type="text" name="name">
<input type="text" name="address">
<input type="text" name="promocode">
<input type="hidden" name="order_price"
value="#OrderValue#>
</form>
process.cfm
======================
<!--- Apply promo code --->
<cfif form.promocode eq "Promo1">
<cfset form.order_price = .75 * form.order_price>
</cfif>
<cfset sales_tax = .1 * form.order_price>
<!--- Send data to processor gateway --->
<cfhttp url="https://www.myProcessor.com/gateway/"
method="POST">
<cfhttpparam type="FORMFIELD" name="price"
value="#form.order_price#">
<cfhttpparam type="FORMFIELD" name="tax"
value="#sales_tax #">
<cfhttpparam type="FORMFIELD" name="cc_number"
value="#cc_num #">
</cfhttp>
<!--- Check response --->
<cfif FindNoCase("Success Text", CFHTTP.fileContent)>
Good Response
<cfelse>
Bad Response
</cfif>