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Andy asks:

This is probably a stupid question but I can't seem to get this to work. I'm using a ColdFusion.Ajax.submitForm and I thought that I would be able to return something from the form's submit handler page using my callback function. I can't seem to get this to work. I tried to a variable on the submit handler page to give it back to the caller page where the form lives but I just get a giant javascript dialog when I try to test this out using an alert in the callback function to display my callbackMsg. Should I be taking a different approach? I really need to get the primary key of the newly inserted record back and can't seem to return it to the calling page.

Now now, Andy, as we all know, there are no stupid questions, just stupid programming languages. That being said, I have a good idea of what you are running into.

Let's start with a super simple example. I'll build a form with two text fields. These fields will represents two numbers. A third field will be used for the answer. Finally I'll add a button:

<form id="myform">
<input type="text" name="number1"> +
<input type="text" name="number2"> =
<input type="text" id="result">
<input type="button" value="Solve" onclick="solve()">
</form>

Notice that the onclick runs solve. Let's look at that:

function solve() {
   console.log('running...');
   ColdFusion.Ajax.submitForm('myform','test.cfm',resultHandler);
   console.log('done...');
}

First and foremost - look at my use of console.log. You need to stop using Alert. I know it's easy. But Alert can be a real pain in the you know what. Download Firebug and get used to doing your debugging there. Ok, so in between two debug statements I'm running a submitForm action. I've said to submit myform to test.cfm and then run resultHandler.

I made test.cfm simply cfoutput a random number for testing purposes.

The first thing I ran into was that ColdFusion.Ajax.submitForm didn't exist. Remember that ColdFusion only loads the Ajax functionality it thinks it needed. Since I didn't really use any ColdFusion tags, it didn't load squat. The trick to handle this was discovered by Todd Sharp, just add this to the top of your page:

<cfajaximport />

Ok, so now I can run my application and see the request, how do we handle it, and why is he getting a large alert? First look at a more full test.cfm:

<cfparam name="form.number1" default="0">
<cfparam name="form.number2" default="0">

<cfset form.number1 = val(form.number1)>
<cfset form.number2 = val(form.number2)>

<cfoutput>#form.number1+form.number2#</cfoutput>

(And by the way, I should be more anal with my URL checks in this code.) Now let's look at resultHandler:

function resultHandler(result) {
   console.log('result handler ran...');
   console.log(result);
}

When I ran my test, I noticed that result was indeed a large string with a lot of white space. That could be what you are seeing in the large alert. The white space is simply a result of ColdFusion liking whitespace like a Lohan needs publicity.

We can fix this a few ways. We can reduce the whitespace in the CFM with a simple CFSETTING. But that's kinda boring. When I saw this on ColdFusionBloggers

Cranky Bit: Trimming a String in JavaScript

I added his code (note his regex is missing a \ in front of each s) and ended up with this:

<script>
String.prototype.trim = function() { return this.replace(/^\s+|\s+$/g,""); }

function resultHandler(result) {
   console.log('result handler ran...');
   console.log(result.trim());
}

function solve() {
   console.log('running...');
   ColdFusion.Ajax.submitForm('myform','test.cfm',resultHandler);
   console.log('done...');
}
</script>

Now when I ran the code I got a nicely trimmed response. I added one more line to set the result value:

document.getElementById("result").value = result.trim();

Comments (10) Jul 3, 2008 11:25 AM Views: 2595

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