Most of us are familiar with the AJAX post() and getJSON() methods of remotely calling and passing around data, I use them with abundance when building applications. One thing I had not considered until recently is that all my AJAX Http requests are usually internal to that application, which also means they are on the same server and domain.

I recently jumped into a project where the application spanned 24 domains, and had been developed to use a core component library to help code re use. The problem with this arose when you are on one domain (www.domain1.com) and you want to make a request to a different domain (www.domain2.com). You encounter something called the 'same-Origin' policy.

This article deals with how to create a proxy to handle cross site AJAX http Requests.

[More]

Im my previous article on how to use the JQuery datatables plug I concentrated mainly on the JQuery script, and how to build the AJAX request to receive a JSON response.

In this article I will demonstrate the full application which will include the front end JQuery, building the back end server response and a few tips that I've picked up since implementing the plugin. I am using an MS SQL table filled with UK location data that I also used for a weather webservice, to fill the table.

A full example of this working can be seen here: Data table server side example

[More]

I recently build an application that returned a JSON object of data based on a select field value. Whilst I was building this I encountered an error using the JavaScript eval() function on my JSON response. I am using the eval() function to parse a string from my JSON response, but firebug is showing a JavaScript error of "Invalid Label".

This is the code:

After having a Google around it appears that the eval function is interpreting the first item in the JSON response as a label, rather than data. By changing the code like this:

We are forcing eval to recognise the data as variable data. Now the JSON to string translation works.

This article will deal with a user choosing a value from a Select field, and that selection being passed to a JQuery handler. The JQuery handler will perform an AJAX request to a CFC, which will return a JSON value (URL String) that we will use to populate an img html tag.

In this way when you select different options from the select field drop down, the image changes inline, without any page reloads.

[More]

This entry examines how the JQuery Carousel object interacts with other Plug-ins, and how to combine those plug-ins with the Carousel functionality. I also cover an issue where the jCarousel plug-in does not apply functionality to non visible elements when the page loads.

[More]

Rather than writing out long winded table code to display your data in a tabulated fashion why not use the dataTables JQuery plugin to do it for you?

In this blog entry I'll be generating tables using a JQuery plugin, but I will also be generating the JQuery code from an XML document.

The theory behind the dataTables JQuery plugin is that when the template loads it makes an AJAX request to a remotely specified template. That template returns a JSON object of data which is formatted and used in a tabular display. This means that you can perfom filtering and sort functions inline, and the JQuery simply re submits the AJAX request, receiving new JSON each time. So no refreshing.

I'll be dealing with the auto generation of the JSON back end in the second part of this article. Here is how I setup the tabular display.

Build a standard html template, including the CSS and JQuery plugins.

Next we build our JQuery function. I wont go into massive detail about all the parameters and values being passed in here, but it is well documented on http://www.datatables.net/.

The really important column here is the "aoColumns" JSON data block. This specifies what fields are returned from your AJAX call, and parameters they must adhere to.

In this example we are anticipating that we will receive four columns of data back (Edit,Band,Genre and Fake Column).

Lastly we create a table with an ID of "example", as this is what the JQuery is looking for. This table must be formatted in a certain way, as the JQuery plugin will re write the specified elements.

The code also contains the header elements that will match the returned column values from the AJAX request. The last part of the table is displayed when the data is loading.

This all works well, but to extend it further I have altered the code to read from an XML document. The XML document Is loaded when the template starts, and the data fields and attributes are read, and looped over to create the JQuery code and table headers. In this way it is a generic table display template, driven from an XML document.

The XML doc:

Read the XML file and parse it out into an Array:

Use something like this to dynamically generate the JQuery and table values:

The JSON response is hard coded in this example, so the result will not filter or search. I'll handle that in article two.

There is a full example of this here.

I've been exploring various methods of using JQuery to populate Select form fields. In the previous article I used an intermediary file to act as a handler for the JSON returned object. In this last article I have removed the extra handler template, interfacing directly with the CFC.

Firstly there are some small changes to the JQuery url call.

Now we are directly referencing the CFC. Simply append the function name as a url parameter. In the "DATA" element we place the data we are passing in the form of key value pairs. This will build all the values into the JQuery url, so the final URL would be:

At this point I was getting an parse error, until I found the 'returnFormat' value. Coldfusion will return WDDX encoded packets by default, problem was my handler was looking for Json. Adding this value will stop this.

Next we have the same form as before, there are no changes at all: (here for completeness really)

Lastly there are one or two small changes to our CFC function.

The access method has changed, so we add an "access=remote" value to expose the function as a service. Then we serialize the query result into JSON, and return it. This seems like a much more succinct way of doing this.