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Adobe Flex: Article

Your First Adobe Flex Application with a ColdFusion Backend

The wow factor plus usability

However, the compiler still complains that it can't find the TaskItem component. "But I just created it!" you say. The problem is that the main application doesn't know where to find it. Since you saved it in the same folder, you have to indicate that other components can be found there by adding the following attribute to the Application tag in the mytodolist.mxml file:

xmlns="*"

Lastly, declare the taskData variable in your new component (TaskItem.mxml) so that it will finally compile without errors:

<mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml" width="100%">
   <mx:Script>
     <![CDATA[
       [Bindable]
       public var taskData:Task = null;
     ]]>
   </mx:Script>
   <!-- place other code here -->
</mx:Canvas>

Why wouldn't it compile? Because when you put the tag <TaskItem> in the main application, you also specified the attribute: taskData="{taskList.currentItem}." This was necessary to be able to send the current task to the custom component during each loop of the Repeater. This variable has to be set as bindable so that you can bind to its properties in the controls inside this component.

If you look carefully, you'll see that this variable has the type "Task." This type refers to the ActionScript file automatically generated by the ColdFusion wizard. The properties of this class match exactly those of your Task ColdFusion component.

An instance of the TaskItem component (Figure 5) shows the description and priority of the task and a button to remove the task. As described above, the data is set when the component is instantiated by the Repeater and accessible in the variable "taskData" inside the component.

You can use the Design view to drag an Image, a Label, and a Button and put it in the Canvas. The Properties panel of the Design view shows common properties of the selected component. In that panel, set the text property of the Label as: {taskData.description} and the source property of the Image as: images/priority{taskData.priority}.png. Note that you should have a folder called "images" with an image for every priority you want to show. These images should be called "priorityNUMBER.png," where NUMBER should be replaced with the priority number (i.e.: 1, 2, 3).

Everything should compile, but unfortunately you won't be able to see anything because there's no data.

Getting Data from a ColdFusion Service
To load data from a service, you must use a RemoteObject. The simplest way to use a RemoteObject to call a ColdFusion service is by setting its destination to "ColdFusion" and its source to the path to that component. The application will call two methods on the TaskGateway component (generated by the wizard) so you can specify them explicitly inside the RemoteObject tag. When the response from the service comes back, you want a function to be called. The function to call will be different for each method, so you can specify it in the <mx:method> tag with the "result" attribute. Set the result of the method "getAll" to the function "tasksReceived(event)" and the result of the method "save" to the function taskSaved(event)."

<mx:RemoteObject
    id="myRemoteObject"
    destination="ColdFusion"
    source="mytodolist.taskGateway"
    fault="Alert.show(event.fault.faultstring, 'Error');">
    <mx:method name="getAll" result="tasksReceived(event)" />
    <mx:method name="save" result="taskSaved(event)" />
</mx:RemoteObject>

Inside a script block, implement the tasksReceived function as follows to set the source of the task ArrayCollection to what the service sent as a response of the getAll method:

private function tasksReceived(event:ResultEvent):void {
    tasks = new ArrayCollection();
    tasks.source = event.result as Array;
}

If you open TaskGateway.cfc, you'll see that the method "getAll" returns an array of Task objects. When you set that array to the source of the tasks ArrayCollection, the Repeater will get populated with this data since you declared it as the Repeater's dataProvider.

If Flex Builder didn't add the required import statements automatically, add:

import mx.controls.Alert;
import mx.rpc.events.*;
import mx.events.*;

The other function you need to implement is taskSaved. For now leave it empty; you'll complete it later.

private function taskSaved(event:ResultEvent):void {
}

Everything works, but...you still don't see anything on the screen. That's because you haven't called the service yet. Since you want to load the list of tasks as soon as the application loads, put a function call in the applicationComplete attribute of the Application tag. You'll set it to call a custom function called setUp():

applicationComplete="setUp()"

Then implement the function so that it sends the actual request to the server:

private function setUp():void{
    myRemoteObject.getAll.send();
}

Of course you still won't see anything if your database is empty. To test it out, just add a couple of records manually. You'll build the form to enter new items in the next section.

More Stories By Nahuel Foronda

Nahuel Foronda is one of the founders of Blue Instant (http://www.blueinstant.com), a web development firm specializing in Rich Internet Applications where he has been creating award-winning applications and offering training for the last five years. He also maintains a blog, called AS Fusion (http://www.asfusion.com), where he writes about Flash, ColdFusion and other web technologies.

More Stories By Laura Arguello

Laura Arguello is one of the founders of Blue Instant (http://www.blueinstant.com), a web development firm specializing in Rich Internet Applications where she has been creating award-winning applications and offering training for the last five years. She also maintains a blog, called AS Fusion (http://www.asfusion.com), where she writes about Flash, ColdFusion and other web technologies.

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Most Recent Comments
??? 10/30/07 01:47:34 AM EDT

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donna 10/12/07 01:28:46 PM EDT

Unable to download the source code. When I got to page http://www.asfusion.com/projects/my-to-do-list/

I received a Coldfusion error:

A License exception has occurred.
You tried to access the Developer Edition from a disallowed IPThe Developer Edition can only be accessed from 127.0.0.1 and two additional IP addresses. The additional IP addresses are: 209.85.238.20,87.194.221.84

There are so many issues encountered with the tutorial apps out there, that dont work when people follow the isntructions exactly. We need apps that work when followed, and we need downloaded source code that will actually be there.

Lara 07/30/07 11:59:27 AM EDT

I am familiar with ColdFusion but completly new to Flex. I can't get the code to work and I am very frustrated. This isn't a good first application example if we can't work the code. Does anyone have the working source files? If so, please post a link to the corrected files. Thanks!

Jason 06/26/07 02:20:44 PM EDT

I love all the article put out by sys-con and found that they are top quality, that is until this one. I have been struggling with learning Flex and found this article and initally was excited because it looked like the article that was going to clear things up. Until I started in and realized that this article is full of mistakes. Flex is VERY case sensitive where as ColdFusion is not. Since this article is target at ColdFusion developers you need to make sure that the code is correct expecially in the area of case sensitivity because we ususally don't think in that manner (it is "faultString" not "faultstring"). Also you need to make sure that you are using the same name for functions. You have us call the addItem() function through a click event but then on the next page we create the saveItem() function to handle that click event. This won't work! Then we need to make changes to the generated CFCs. You show us the two lines of code that we need to add and simply state that they "should be added to the 'create' method." Ok, but where in the create method. I moved them all over and I continually get errors. I have yet to find a competent article for the Flex "newbie" that achieves its goal of showing how to do basic updates and adds with Flex and CF. I thought that this was going to be the one. Guess I was wrong!

KTK 06/07/07 03:53:09 PM EDT

I'm glad it's not just me! I've had to put this aside for a couple weeks to work on a CF project. Hopefully I can get back to it later this month. If you figure something out, let me know and if I figure it out, I'll let you know. In the meantime, maybe a savior will come along for both of us!

Scott 06/07/07 01:30:06 PM EDT

KTK - I have the same problem and I followed all of the instructions exactly.

Uf!

KTK 06/04/07 01:28:59 PM EDT

I'm getting an error that says "A file found in a source-path must have the same package structure '', as the definition's package, 'Task'. I've been beating my head against it for hours and can't figure out why I'm getting the error. Any ideas?

jex 11/04/06 11:26:10 AM EST

OK - I'm a bit new to both Flex and CF, but have been implementing the tutorial fine up until: "Going back to the main application file (mytodolist.mxml), switch to the design view and drag a new panel and inside drag your EditForm component." When I drag the EditForm component onto the panel, nothing happens. Would it be possible to explain exactly what has to be done here? Many thanks.

jex 11/04/06 11:24:25 AM EST

Problem solved - I was trying to drag the EditForm.mxml - but it's the EditForm component(as it says in the tutorial)which needs to be dragged - this is found in the custom component folder.

jex 11/04/06 10:19:33 AM EST

OK - I'm a bit new to both Flex and CF, but have been implementing the tutorial fine up until: "Going back to the main application file (mytodolist.mxml), switch to the design view and drag a new panel and inside drag your EditForm component." When I drag the EditForm component onto the panel, nothing happens. Would it be possible to explain exactly what has to be done here? Many thanks.

Francois-Yanick Bourassa 08/09/06 04:21:30 PM EDT

I found myself a bit confused to follow this article as it is a bit out of the real target - which is bringing new people to use Flex and ColdFusion. As a ColdFusion programmer, I found very interesting to try this example with Flex. But after couple paragraphs, started to be confused on which file I was suppose to put the code as Flex is a real new thing for me - I'm sure it will be the same for few of us - if it is not more! We use to read article where editor just put rectangle on source code by page - but this article seems to have a different goal!

I will figure out what was wrong in the code because I think I can but what about newbies!!!

This was my personal feedback!

AJAXWorld News Desk 08/09/06 08:35:47 AM EDT

Flex is a complete set of tools to develop rich Internet cross-platform applications based on the Flash platform. With Flex, you can create applications that not only have the 'wow factor' necessary to please clients and users alike, but the 'usability factor' necessary to make your application a real success.

cfdj news desk 08/08/06 08:29:03 PM EDT

Flex is a complete set of tools to develop rich Internet cross-platform applications based on the Flash platform. With Flex, you can create applications that not only have the 'wow factor' necessary to please clients and users alike, but the 'usability factor' necessary to make your application a real success.

CFDJ News Desk 08/08/06 07:25:22 PM EDT

Flex is a complete set of tools to develop rich Internet cross-platform applications based on the Flash platform. With Flex, you can create applications that not only have the 'wow factor' necessary to please clients and users alike, but the 'usability factor' necessary to make your application a real success.

AJAXWorld News Desk 08/08/06 07:11:51 PM EDT

Flex is a complete set of tools to develop rich Internet cross-platform applications based on the Flash platform. With Flex, you can create applications that not only have the 'wow factor' necessary to please clients and users alike, but the 'usability factor' necessary to make your application a real success.

AJAXWorld News Desk 08/07/06 03:11:03 PM EDT

Flex is a complete set of tools to develop rich Internet cross-platform applications based on the Flash platform. With Flex, you can create applications that not only have the 'wow factor' necessary to please clients and users alike, but the 'usability factor' necessary to make your application a real success.

SYS-CON Australia News Desk 08/07/06 09:34:46 AM EDT

Flex is a complete set of tools to develop rich Internet cross-platform applications based on the Flash platform. With Flex, you can create applications that not only have the 'wow factor' necessary to please clients and users alike, but the 'usability factor' necessary to make your application a real success.

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