AJAX request post parameters not recognized in ColdFusion form scope

I am currently developing a ColdFusion 8 training application that involves creating AJAX requests without using any libraries like jQuery. This is to support a basic CRUD application where data is retrieved and processed through various layers of the system. The architecture consists of a CFM view, a CFC with remote access methods handling the AJAX requests, and another CFC acting as a model responsible for all database queries. When retrieving data that does not require bind variables such as fetching all rows from a table, the AJAX queries work seamlessly. However, I encounter errors when attempting to send data to the middle layer CFC. The error messages indicate that the values expected are undefined in the Form scope, which is where post parameters should be stored according to my understanding. Even after dissecting the requests with Tamper Data and confirming that the names and values of the post parameters match my expectations, the issue persists.

Below is an example snippet of the JavaScript AJAX requests:

    function addLocation(locToAdd) {
            var thisAccess = new AccessStruct("POST", "jsontest.cfc?method=addNewLocation", getLocations, "newLoc=" + JSON.stringify(locToAdd));
            accessWrapper("addLoc", thisAccess);

    function accessWrapper(action, accessDef) {
            var ajaxRequest = new XMLHttpRequest();
            
            // Additional code omitted for brevity
                        
            }

The page functionality involves rendering a table of location records for a user and providing a form to add a new record. When the user submits the form, a Loc structure capturing their input is created and passed to the addLocation function. This function then constructs an Access structure containing relevant information including the request URL, method, callback function name, and post parameters. The accessWrapper function, in turn, initializes the XMLHttpRequest object and processes the AJAX request. A closure is utilized within the onreadystatechange callback function to interact with the XMLHttpRequest object and execute the designated callback function for actions like adding, deleting, or editing records.

The following excerpt showcases the cffunction within the middle-layer CFC where the reported problem arises:

 <cffunction name="addNewLocation" output="false" access="remote">
    <cfset var deserializedLocation = "">
    <cfscript>
        deserializedLocation = DeserializeJSON(Form.newLoc);
    </cfscript> 
    
    // Additional code omitted for brevity

</cffunction>

The response error states: 500 Element NEWLOC is undefined in FORM

Despite verifying the request through Tamper Data and ensuring its correctness, the error persists. Any assistance provided would be greatly appreciated!

Answer №1

Indeed, when performing an Ajax post to a CFC, there is a definitely a FORM scope present.

In this instance, form data is transmitted via Ajax to a CFC function without any arguments, and the resulting output is in JSON format from the FORM scope. While it's advisable to include arguments to document specifics like required fields and data types, they are not strictly necessary.

Have you considered using jQuery? Incorporating it could greatly simplify your tasks.

If you're encountering issues, it may be related to how the form data is being sent to the Ajax call. Utilizing tools like FireBug allows for monitoring of POSTed parameters during Ajax calls.

HTML

<html>
    <head>
        <title>Ajax POST to CFC</title>
        <script src="//ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
        <script type="text/javascript" src="test.js">
    </head>
    <body>

        <form id="foo" action="" method="post">

            <input type="text" id="a" name="a" value="Hello" />
            <br />
            <input type="text" id="b" name="b" value="Goodbye" />
            <br />

            <textarea id="data" cols="30" rows="10" disabled="true"></textarea>
            <br />
            <input type="button" id="btnSubmit" value="Do Ajax!" />

        </form>

    </body>

</html>

JavaScript

<pre><code><pre><code><pre><code><pre>function doSubmit(){
    var http = new XMLHttpRequest();
    var url = "test.cfc";
    var params = "method=testing&returnformat=json";
        params += "&a=" + document.getElementById('a').value;
        params += "&b=" + document.getElementById('b').value;
    http.open("POST", url, true);
    //Send the proper header information along with the request
    http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    http.setRequestHeader("Content-length", params.length);
    http.setRequestHeader("Connection", "close");
    http.onreadystatechange = function() {//Call a function when the state changes.
        if(http.readyState == 4 && http.status == 200) {
            document.getElementById('data').value = http.responseText;
        }
    }
    http.send(params);
}</pre>

Answer №2

Transform newLoc into a parameter and the solution should be functional.

<cffunction name="addNewLocation" output="false" access="remote">
  <cfargument name="newLoc">
  ...

</cffunction>

update: I'm unsure why there was a lack of form scope during one instance when invoking a remote procedure. Nevertheless, this doesn't negate the validity of the remainder of the response.

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