Welcome!

Adobe Flex Authors: Matthew Lobas, PR.com Newswire, Shelly Palmer, Kevin Benedict

Related Topics: Adobe Flex, ColdFusion

Adobe Flex: Article

Adobe Flex 2: Advanced DataGrid

Part 1: Destination-awareness formatters & renderers

In any GUI tool, one of the most popular components is the one that shows data in a table format like JTable in Java or Datawindow in PowerBuilder. The Adobe Flex 2 version of such a component is called DataGrid. In any UI framework, the robustness of such a component depends on formatting and validating utilities as well as a whole suite of data input controls: CheckBoxes, ComboBoxes, RadioButtons, all sorts of Inputs, Masks, and so on. Using theatrical terminology, the role of the king is played by his entourage. Practically speaking, touching up the DataGrid is touching up a large portion of the Flex framework.

We'll start by upgrading the standard DataGrid to a "destination-aware" control capable of populating itself. Next, we'll look at the task of formatting DataGrid columns and that would naturally lead us to a hidden treasury of the Flex DataGrid - the DataGridColumn, which, once you start treating it like a companion rather than a dull element of MXML syntax, can help you do truly amazing things.

After setting the stage for the DataGrid's satellite controls, we'll lead you through making a professional library with a component manifest file and namespace declaration that supports flexible mappings of your custom tags to the required hierarchy of implementation classes.

Making DataGird Destination-Aware
Introducing Flex remoting substantially increased the size of our application code. Imagine a real-world application with two-dozen different ComboBoxes or DataGrids. If we put all the relevant RemoteObjects in a single application file it will become unmanageable in no time. For similar reasons, any decent sized application is usually partitioned into different files.

As far as partitioning goes, there's a compelling argument to encapsulate instantiation and interoperation with RemoteObject inside the visual component, making it a destination-aware component, if you will. Embedding a Remote Object directly into the DataGrid will make it fully autonomous and reusable. This design approach sets application business logic free from low-level details like mundane remoting.

The concept of destination-aware controls eliminates the tedious effort required to populate your controls with Remoting or DataServices-based data. Here's how an MXML application with a destination-aware DataGrid might look if we apply the familiar remoting destination com_theriabook_composition_EmployeeDAO:

<!-- DestinationAwareDataGridExDemo.mxml-->
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx=http://www.adobe.com/2006/mxml layout="vertical"
        xmlns:fx="com.theriabook.controls.*">
        <fx:DataGridEx id="dg"
     destination="com_theriabook_composition_EmployeeDAO"
     method="getEmployees" creationComplete="dg.fill()"/>
</mx:Application>

In Listing 1 we have sub-classed the standard Flex DataGrid.

The data are coming from a server-side database with the help of a Java object called EmployeeDAO. If we run the application, our screen will show the grid of employee records in its default formatting:. (See Figure 1).

Formatting with labelFunction
We have just looked at the default data formatting provided by DataGrid out-of-the-box. The easiest way to improve column formatting is by supplying a labelFunction for each column that requires extra attention:

     <mx:DataGridColumn dataField="PHONE" labelFunction="phoneLabelFunction" />

Once the labelFunction is declared it automatically gets called by the DataGrid, which supplies the appropriate data item plus information about the column so that you can technically apply one function to more than one column. As far as the formatting techniques themselves, Flex offers plenty of pre-defined formatters, which can be used out-of-the-box or customized to your specific needs. For instance, to format Social Security numbers (SS_NUMBER), we could have used mx.formatters.SwitchSymbolFormatter to create the following function:

    import mx.formatters.SwitchSymbolFormatter;
    private var sf:SwitchSymbolFormatter;
    private function ssnLabelFunction(item:Object, column:DataGridColumn):String {
      if (!sf) {
        sf = new SwitchSymbolFormatter();
      }
      return sf.formatValue("###-##-####", item["SS_NUMBER"]);
      }

Then inside the DataGridColumn we can mention this function name:

     <mx:DataGridColumn dataField="SS_NUMBER" labelFunction="ssnLabelFunction" />

Similarly, in Listing 2 we can apply the same technique to the PHONE field setting the formatString to (###)###-####.

Figure 2 shows how our formatting looks on the screen.

Formatting with Extended DataGridColumn
The labelFunction formatting does the job. The price tag is hard-coding labelFunction(s) names in the DataGridColumn definitions. If you packaged a set of label functions in the class mydomain.LabelFunction your column definitions might look like this:

<mx:DataGridColumn    dataField="PHONE" labelFunction="mydomain.LabelFunctions.phone" />
<mx:DataGridColumn    dataField="SS_NUMBER" labelFunction=" mydomain.LabelFunctions.ssn" />

A more pragmatic approach is to provide the formatString as an extra attribute to the DataGridColumn and have it encapsulate the implementation details. We're talking of the following alternative:

<fx:DataGridColumn    dataField="PHONE" formatString="phone" />
<fx:DataGridColumn    dataField="SS_NUMBER" formatString="ssn" />

Implementing such syntax is within arm's reach. We just have to extend - well, not the arm, but the DataGridColumn so that instead of mx:DataGridColumn we would use our, say, fx:DataGridColumn. The mx.controls.dataGridClasses.DataGridColumn is just a respository of styles and properties to be used by the DataGrid. In the Flex class hierarchy it merely extends CSSStyleDeclaration. Nothing prevents us from extending it further and adding an extra attribute. In the case of formatString the setter function will delegate assigning the labelFunction to the helper FormattingManager:

    public class DataGridColumn extends mx.controls.dataGridClasses.DataGridColumn {
      public function set formatString( fs:String ) : void{
        FormattingManager.setFormat(this, fs);
      }
    }

Wait a minute, where did the FormattingManager come from? We'll get to the implementation of this class later. At this point, we have to eliminate the possible naming collision between our to-be-made DataGridColumn and the standard mx.controls.dataGridClasses.DataGridColumn.

Introducing the Component Manifest File
Up till now we've been keeping folders with classes of our custom components under the folder of application MXML files. To reference these components we've been declaring namespaces pointing to some hard-coded, albeit relative paths, such as xmlns:lib="com.theriabook.controls.*" or xmlns="*". The problem with this approach is that these namespaces point to one folder at a time. As a result, we either end up with multiple custom name spaces or we have a wild mix of components in one folder.

To break the spell and abstract the namespace from the exact file location we need to use the component manifest file. Component manifest is an XML file that allows mapping of component names to the implementing classes. Below is the example of component manifest, which combines our custom DataGrid and DataGridColumn located in different folders:

<?xml version="1.0"?>
<componentPackage>
    <component id="DataGrid" class="com.theriabook.controls.DataGrid"/>
    <component id="DataGridColumn"
    class="com.theriabook.controls.dataGridClasses.DataGridColumn"/>
</componentPackage>

To benefit from using this component manifest you have to compile your components with the compc or use the Flex Library project. To be more specific, you have to instruct compc to select the URL that your application can use later in place of the hard-coded folder in the xmlns declaration. So we'll create a new FlexLibrary project - theriabook, where we'll put the theriabook-manifest.xml containing the XML above and set the relevant project properties, as shown in Figure 3.

Now we can move DataGrid from our application project to theriabook and replace xmlns:fx="com.theriabook.controls" with xmlns:fx="http://www.theriabook.com/2006" provided that our application project will include a reference to theriabook.swc. As a result our application will reference fx:DataGrid and fx:DataGridColumn irrespective to their physical location.

Having done that, let's get back to the custom DataGridColumn.


More Stories By Victor Rasputnis

Dr. Victor Rasputnis is a Managing Principal of Farata Systems. He's responsible for providing architectural design, implementation management and mentoring to companies migrating to XML Internet technologies. He holds a PhD in computer science from the Moscow Institute of Robotics. You can reach him at [email protected]

More Stories By Yakov Fain

Yakov Fain is a Java Champion and a co-founder of the IT consultancy Farata Systems and the product company SuranceBay. He wrote a thousand blogs (http://yakovfain.com) and several books about software development. Yakov authored and co-authored such books as "Angular 2 Development with TypeScript", "Java 24-Hour Trainer", and "Enterprise Web Development". His Twitter tag is @yfain

More Stories By Anatole Tartakovsky

Anatole Tartakovsky is a Managing Principal of Farata Systems. He's responsible for creation of frameworks and reusable components. Anatole authored number of books and articles on AJAX, XML, Internet and client-server technologies. He holds an MS in mathematics. You can reach him at [email protected]

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
SYS-CON Events announced today that Bsquare has been named “Silver Sponsor” of SYS-CON's @ThingsExpo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. For more than two decades, Bsquare has helped its customers extract business value from a broad array of physical assets by making them intelligent, connecting them, and using the data they generate to optimize business processes.
The vision of a connected smart home is becoming reality with the application of integrated wireless technologies in devices and appliances. The use of standardized and TCP/IP networked wireless technologies in line-powered and battery operated sensors and controls has led to the adoption of radios in the 2.4GHz band, including Wi-Fi, BT/BLE and 802.15.4 applied ZigBee and Thread. This is driving the need for robust wireless coexistence for multiple radios to ensure throughput performance and th...
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management solutions, helping companies worldwide activate their data to drive more value and business insight and to transform moder...
SYS-CON Events announced today that Pulzze Systems will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Pulzze Systems, Inc. provides infrastructure products for the Internet of Things to enable any connected device and system to carry out matched operations without programming. For more information, visit http://www.pulzzesystems.com.
Enterprise IT has been in the era of Hybrid Cloud for some time now. But it seems most conversations about Hybrid are focused on integrating AWS, Microsoft Azure, or Google ECM into existing on-premises systems. Where is all the Private Cloud? What do technology providers need to do to make their offerings more compelling? How should enterprise IT executives and buyers define their focus, needs, and roadmap, and communicate that clearly to the providers?
SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. Big Data at Cloud Expo - to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is...
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
Digital innovation is the next big wave of business transformation based on digital technologies of which IoT and Big Data are key components, For example: Business boundary innovation is a challenge to excavate third-party business value using IoT and BigData, like Nest Business structure innovation may propose re-building business structure from scratch, as Uber does in the taxicab industry The social model innovation is also a big challenge to the new social architecture with the design fr...
Data is an unusual currency; it is not restricted by the same transactional limitations as money or people. In fact, the more that you leverage your data across multiple business use cases, the more valuable it becomes to the organization. And the same can be said about the organization’s analytics. In his session at 19th Cloud Expo, Bill Schmarzo, CTO for the Big Data Practice at EMC, will introduce a methodology for capturing, enriching and sharing data (and analytics) across the organizati...
IoT is fundamentally transforming the auto industry, turning the vehicle into a hub for connected services, including safety, infotainment and usage-based insurance. Auto manufacturers – and businesses across all verticals – have built an entire ecosystem around the Connected Car, creating new customer touch points and revenue streams. In his session at @ThingsExpo, Macario Namie, Head of IoT Strategy at Cisco Jasper, will share real-world examples of how IoT transforms the car from a static p...
The many IoT deployments around the world are busy integrating smart devices and sensors into their enterprise IT infrastructures. Yet all of this technology – and there are an amazing number of choices – is of no use without the software to gather, communicate, and analyze the new data flows. Without software, there is no IT. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists will look at the protocols that communicate data and the emerging data analy...
SYS-CON Events announced today that China Unicom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. China United Network Communications Group Co. Ltd ("China Unicom") was officially established in 2009 on the basis of the merger of former China Netcom and former China Unicom. China Unicom mainly operates a full range of telecommunications services including mobile broadband (GSM, WCDMA, LTE F...
The Transparent Cloud-computing Consortium (abbreviation: T-Cloud Consortium) will conduct research activities into changes in the computing model as a result of collaboration between "device" and "cloud" and the creation of new value and markets through organic data processing High speed and high quality networks, and dramatic improvements in computer processing capabilities, have greatly changed the nature of applications and made the storing and processing of data on the network commonplace.
Big Data has been changing the world. IoT fuels the further transformation recently. How are Big Data and IoT related? In his session at @BigDataExpo, Tony Shan, a renowned visionary and thought leader, will explore the interplay of Big Data and IoT. He will anatomize Big Data and IoT separately in terms of what, which, why, where, when, who, how and how much. He will then analyze the relationship between IoT and Big Data, specifically the drilldown of how the 4Vs of Big Data (Volume, Variety,...
Video experiences should be unique and exciting! But that doesn’t mean you need to patch all the pieces yourself. Users demand rich and engaging experiences and new ways to connect with you. But creating robust video applications at scale can be complicated, time-consuming and expensive. In his session at @ThingsExpo, Zohar Babin, Vice President of Platform, Ecosystem and Community at Kaltura, will discuss how VPaaS enables you to move fast, creating scalable video experiences that reach your...
If you’re responsible for an application that depends on the data or functionality of various IoT endpoints – either sensors or devices – your brand reputation depends on the security, reliability, and compliance of its many integrated parts. If your application fails to deliver the expected business results, your customers and partners won't care if that failure stems from the code you developed or from a component that you integrated. What can you do to ensure that the endpoints work as expect...
WebRTC adoption has generated a wave of creative uses of communications and collaboration through websites, sales apps, customer care and business applications. As WebRTC has become more mainstream it has evolved to use cases beyond the original peer-to-peer case, which has led to a repeating requirement for interoperability with existing infrastructures. In his session at @ThingsExpo, Graham Holt, Executive Vice President of Daitan Group, will cover implementation examples that have enabled ea...
Almost two-thirds of companies either have or soon will have IoT as the backbone of their business in 2016. However, IoT is far more complex than most firms expected. How can you not get trapped in the pitfalls? In his session at @ThingsExpo, Tony Shan, a renowned visionary and thought leader, will introduce a holistic method of IoTification, which is the process of IoTifying the existing technology and business models to adopt and leverage IoT. He will drill down to the components in this fra...
The Internet of Things can drive efficiency for airlines and airports. In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect with GE, and Sudip Majumder, senior director of development at Oracle, will discuss the technical details of the connected airline baggage and related social media solutions. These IoT applications will enhance travelers' journey experience and drive efficiency for the airlines and the airports. The session will include a working demo and a technical d...