Styjun

I am developing a web application in Cl-who, Hunchentoot, and Common Lisp that will need to process customer orders. Since they could obviously order more than one item, I figured a Checkbox would make the most sense. However, the issue is when I define an easy-handler, it doesn't receive the array of results like an array in PHP if you have a series of Checkboxes with the same name and different values. Instead, it treats the variable as a String, so I cannot iterate over each Box that was checked. Here is a snippet of my code:

(:input :type "checkbox" :name "food[]" :value "cheese balls")
(:input :type "checkbox" :name "food[]" :value "fries")
(:input :type "checkbox" :name "food[]" :value "hamburger")

Here is the handler I have set up (maybe I need to use the loop macro here?) This is just a sample because I will obviously process each argument passed to the easy-handler when I figure out this problem:

(define-easy-handler (process-order :uri "/process-order") 
 (customer-name customer-address customer-city customer-phone order-type food[])
 (standard-page (:title "order results"
 :href "file.css")
 (:h1 (if food[]
 (dolist (x food[])
 (:li (fmt "We see that you want ~A~%" x)))))))

Those are just three potential inputs that someone could check. So lets assume that a customer checks all three... Only cheese balls would return because Lisp is treating the name "food[]" as an individual string. What I mean by that is that in PHP that variable for name ("food[]") would be processed as if it were an array. So in HTML and PHP it would look something like this:

<input type="checkbox" name="food[]" value="cheese balls" class="check"/>
<input type="checkbox" name="food[]" value="fries" class="check"/>
<input type="checkbox" name="food[]" value="hamburger" class="check"/>

Assuming a customer selected all three Checkboxes, I could do something similar to this in PHP:

if( isset( $_POST['food'])) 
 foreach ( $_POST['food'] as $food)
 echo $food;
 
 

It is not clear how you'd achieve similar functionality in Common Lisp with Cl-WHO and Hunchentoot however. The only other alternative I can think of is passing like 30 parameters to the easy-handler, but that sounds like the least efficient way to solve this problem. I know that there is also a CL form processing library, but I was hoping to avoid going down that route, although I will if that's the only possible solution. Giving each checkbox a different name seems like the worst possible way to solve this.

After further reading the documentation, you can alter the parameter type that the easy handler expects to receive. As soon as it sees that it is a list in the parameter definition, it treats it as a List. I simply changed my food parameter to this:

(food[] :parameter-type 'list)

And it treats it as if it where a list and retrieves multiple results from my CheckBoxes.