After searching around for countless hours, trying some test code samples, and even talking to the ColdFusion master himself (Ben Forta), I have come to find that it is IMPOSSIBLE to use HTML input form arrays with ColdFusion. If you've ever run into problems trying to get ColdFusion to recognize similar input items in a collection, there is a solution at the bottom of this page.

I'm a tried-and-true PHP/C#.NET programmer and am very comfortable with the C-based language syntax structure. And in previous web projects with other companies I've worked for, I was easily able to create HTML form input arrays out of whatever type of elements I wanted to use, whether TEXTAREA, INPUT, SELECT.

Here is a code snippet showing how I would create the HTML form input arrays:
(take notice of the empty value for the 3rd textbox item, this will illustrate my point later on)
Here is the "code behind" page in PHP that I'd use to receive and loop through those FORM post values:
Here is the "code behind" page in C#.NET that I'd use to receive and loop through those FORM post values:
An added benefit of using an HTML form input array is in JavaScript validation. Traversing through the array of input items is a cinch when HTML input fields have the same name and are of the same datatype. Here's a sample of how you could use JavaScript to validate the HTML form input array fields when the form is submitted: The output of the PHP or C#.NET code would look something like the following:
Here is the "code behind" page in ColdFusion that I'd use to receive those FORM post values in ColdFusion:
When ColdFusion receives the HTML input array, it immediately converts it into a ColdFusion datatype called a List. ColdFusion Lists are different from ColdFusion Arrays, mainly in that ColdFusion Lists are text strings that use a delimiter, and ColdFusion Arrays have a 1-based index (yes, not 0-based!) that is used to reference the data at that position in the array. ColdFusion Lists cannot by definition contain a null or empty string variable, and so when ColdFusion parses the HTML input form elements, it will drop any items that did not have values given to them before the time of form submission. The output of the ColdFusion code from the same HTML input form used before would look something like the following:
Notice the missing "empty" line for our 3rd input item that was left blank? It has been removed by the ColdFusion parser and thus the indices of items 4-6 have been shifted to indices 3-5. As you can imagine, this becomes a serious problem if you are using multiple HTML form input array items (ie: Last_Name, MI, and First_Name) and some of the fields are left blank by the user who is filling out the HTML form.


THE COLDFUSION GURU:

After finding myself quite frustrated with how ColdFusion handles these input arrays, I decided to put together a well-thought question and fire it off to Ben Forta. To my great suprise, he wrote me back the very next morning with the following response:

THE FIX:

So by now you are wondering how we'll be able to achieve the same functionality in ColdFusion as we currently have in PHP and C#.NET. The answer isn't exciting, and is a bit more difficult programmatically, but it IS possible to achieve the same functionality. You just have to be a bit more careful about how you go about things, so if you are methodical in your process, you'll be ok.

The NEW HTML input form should look like the following:
The NEW JavaScript validation code for this input page could look like the following:
The NEW ColdFusion form response page should look like the following:
The output of this new ColdFusion code would look something like the following:
There you have it. How to programmatically use HTML form input arrays (well, these are actually not real arrays) with ColdFusion 7. Now try out these samples and get back to coding!

- Justin Tubbs