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 vrasputnis@faratasystems.com

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 atartakovsky@faratasystems.com

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
The financial services market is one of the most data-driven industries in the world, yet it’s bogged down by legacy CPU technologies that simply can’t keep up with the task of querying and visualizing billions of records. In his session at 20th Cloud Expo, Karthik Lalithraj, a Principal Solutions Architect at Kinetica, discussed how the advent of advanced in-database analytics on the GPU makes it possible to run sophisticated data science workloads on the same database that is housing the rich...
IoT is at the core or many Digital Transformation initiatives with the goal of re-inventing a company's business model. We all agree that collecting relevant IoT data will result in massive amounts of data needing to be stored. However, with the rapid development of IoT devices and ongoing business model transformation, we are not able to predict the volume and growth of IoT data. And with the lack of IoT history, traditional methods of IT and infrastructure planning based on the past do not app...
With tough new regulations coming to Europe on data privacy in May 2018, Calligo will explain why in reality the effect is global and transforms how you consider critical data. EU GDPR fundamentally rewrites the rules for cloud, Big Data and IoT. In his session at 21st Cloud Expo, Adam Ryan, Vice President and General Manager EMEA at Calligo, will examine the regulations and provide insight on how it affects technology, challenges the established rules and will usher in new levels of diligence...
DX World EXPO, LLC., a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
In the enterprise today, connected IoT devices are everywhere – both inside and outside corporate environments. The need to identify, manage, control and secure a quickly growing web of connections and outside devices is making the already challenging task of security even more important, and onerous. In his session at @ThingsExpo, Rich Boyer, CISO and Chief Architect for Security at NTT i3, discussed new ways of thinking and the approaches needed to address the emerging challenges of security i...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devic...
What sort of WebRTC based applications can we expect to see over the next year and beyond? One way to predict development trends is to see what sorts of applications startups are building. In his session at @ThingsExpo, Arin Sime, founder of WebRTC.ventures, discussed the current and likely future trends in WebRTC application development based on real requests for custom applications from real customers, as well as other public sources of information.
"The Striim platform is a full end-to-end streaming integration and analytics platform that is middleware that covers a lot of different use cases," explained Steve Wilkes, Founder and CTO at Striim, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
SYS-CON Events announced today that Calligo, an innovative cloud service provider offering mid-sized companies the highest levels of data privacy and security, has been named "Bronze Sponsor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Calligo offers unparalleled application performance guarantees, commercial flexibility and a personalised support service from its globally located cloud plat...
SYS-CON Events announced today that Massive Networks will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Massive Networks mission is simple. To help your business operate seamlessly with fast, reliable, and secure internet and network solutions. Improve your customer's experience with outstanding connections to your cloud.
SYS-CON Events announced today that DXWorldExpo has been named “Global Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Digital Transformation is the key issue driving the global enterprise IT business. Digital Transformation is most prominent among Global 2000 enterprises and government institutions.
SYS-CON Events announced today that Datera, that offers a radically new data management architecture, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datera is transforming the traditional datacenter model through modern cloud simplicity. The technology industry is at another major inflection point. The rise of mobile, the Internet of Things, data storage and Big...
While the focus and objectives of IoT initiatives are many and diverse, they all share a few common attributes, and one of those is the network. Commonly, that network includes the Internet, over which there isn't any real control for performance and availability. Or is there? The current state of the art for Big Data analytics, as applied to network telemetry, offers new opportunities for improving and assuring operational integrity. In his session at @ThingsExpo, Jim Frey, Vice President of S...
"DX encompasses the continuing technology revolution, and is addressing society's most important issues throughout the entire $78 trillion 21st-century global economy," said Roger Strukhoff, Conference Chair. "DX World Expo has organized these issues along 10 tracks with more than 150 of the world's top speakers coming to Istanbul to help change the world."
"We provide IoT solutions. We provide the most compatible solutions for many applications. Our solutions are industry agnostic and also protocol agnostic," explained Richard Han, Head of Sales and Marketing and Engineering at Systena America, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We are focused on SAP running in the clouds, to make this super easy because we believe in the tremendous value of those powerful worlds - SAP and the cloud," explained Frank Stienhans, CTO of Ocean9, Inc., in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We've been engaging with a lot of customers including Panasonic, we've been involved with Cisco and now we're working with the U.S. government - the Department of Homeland Security," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
Everything run by electricity will eventually be connected to the Internet. Get ahead of the Internet of Things revolution and join Akvelon expert and IoT industry leader, Sergey Grebnov, in his session at @ThingsExpo, for an educational dive into the world of managing your home, workplace and all the devices they contain with the power of machine-based AI and intelligent Bot services for a completely streamlined experience.
"MobiDev is a Ukraine-based software development company. We do mobile development, and we're specialists in that. But we do full stack software development for entrepreneurs, for emerging companies, and for enterprise ventures," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
SYS-CON Events announced today that DXWorldExpo has been named “Global Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Digital Transformation is the key issue driving the global enterprise IT business. Digital Transformation is most prominent among Global 2000 enterprises and government institutions.