Click here to close now.

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 co-founder of two software companies: Farata Systems and SuranceBay. He authored several technical books and lots of articles on software development. Yakov is Java Champion (https://java-champions.java.net). He leads leads Princeton Java Users Group. Two of Yakov's books will go in print this year: "Enterprise Web Development" (O'Reilly) and "Java For Kids" (No Starch Press).

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 Secure Infrastructure & Services will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Secure Infrastructure & Services (SIAS) is a managed services provider of cloud computing solutions for the IBM Power Systems market. The company helps mid-market firms built on IBM hardware platforms to deploy new levels of reliable and cost-effective computing and high availability solutions, leveraging the cloud and the benefits of Infrastructure-as-a-Service (IaaS...
The enterprise market will drive IoT device adoption over the next five years. In his session at @ThingsExpo, John Greenough, an analyst at BI Intelligence, division of Business Insider, analyzed how companies will adopt IoT products and the associated cost of adopting those products. John Greenough is the lead analyst covering the Internet of Things for BI Intelligence- Business Insider’s paid research service. Numerous IoT companies have cited his analysis of the IoT. Prior to joining BI Intelligence, he worked analyzing bank technology for Corporate Insight and The Clearing House Payment...
SYS-CON Events announced today that ProfitBricks, the provider of painless cloud infrastructure, will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. ProfitBricks is the IaaS provider that offers a painless cloud experience for all IT users, with no learning curve. ProfitBricks boasts flexible cloud servers and networking, an integrated Data Center Designer tool for visual control over the cloud and the best price/performance value available. ProfitBricks was named one of the coolest Clo...
The 4th International Internet of @ThingsExpo, co-located with the 17th International Cloud Expo - to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA - announces that its Call for Papers is open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than
"In the IoT space we are helping customers, mostly enterprises and industry verticals where time-to-value is critical, and we help them with the ability to do faster insights and actions using our platform so they can transform their business operations," explained Venkat Eswara, VP of Marketing at Vitria, in this SYS-CON.tv interview at @ThingsExpo, held June 9-11, 2015, at the Javits Center in New York City.
SYS-CON Events announced today that WHOA.com, an ISO 27001 Certified secure cloud computing company, participated as “Bronze Sponsor” of SYS-CON's 16th International Cloud Expo® New York, which took place June 9-11, 2015, at the Javits Center in New York City, NY. WHOA.com is a leader in next-generation, ISO 27001 Certified secure cloud solutions. WHOA.com offers a comprehensive portfolio of best-in-class cloud services for business including Infrastructure as a Service (IaaS), Secure Cloud Desktop, Cloud Storage, Disaster Recovery, Integrated Applications and Security.
SYS-CON Events announced today that Intelligent Systems Services will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Established in 1994, Intelligent Systems Services Inc. is located near Washington, DC, with representatives and partners nationwide. ISS’s well-established track record is based on the continuous pursuit of excellence in designing, implementing and supporting nationwide clients’ mission-critical systems. ISS has completed many successful projects in Healthcare, Commercial, Manu...
The Internet of Things is not only adding billions of sensors and billions of terabytes to the Internet. It is also forcing a fundamental change in the way we envision Information Technology. For the first time, more data is being created by devices at the edge of the Internet rather than from centralized systems. What does this mean for today's IT professional? In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists addressed this very serious issue of profound change in the industry.
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th 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 an...
SYS-CON Events announced today that kintone has been named “Bronze Sponsor” of SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. kintone promotes cloud-based workgroup productivity, transparency and profitability with a seamless collaboration space, build your own business application (BYOA) platform, and workflow automation system.
SYS-CON Events announced today that SoftLayer, an IBM company, has been named “Gold Sponsor” of SYS-CON's 17th International Cloud Expo®, which will take place November 3–5, 2015 at the Santa Clara Convention Center in Santa Clara, CA. SoftLayer operates a global cloud infrastructure platform built for Internet scale. With a global footprint of data centers and network points of presence, SoftLayer provides infrastructure as a service to leading-edge customers ranging from Web startups to global enterprises. SoftLayer’s modular architecture, full-featured API, and sophisticated automation pro...
Discussions about cloud computing are evolving into discussions about enterprise IT in general. As enterprises increasingly migrate toward their own unique clouds, new issues such as the use of containers and microservices emerge to keep things interesting. In this Power Panel at 16th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the state of cloud computing today, and what enterprise IT professionals need to know about how the latest topics and trends affect their organization.
17th Cloud Expo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterprises are using some form of XaaS – software, platform, and infrastructure as a service.
SYS-CON Events announced today that CommVault has been named “Bronze Sponsor” of SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. A singular vision – a belief in a better way to address current and future data management needs – guides CommVault in the development of Singular Information Management® solutions for high-performance data protection, universal availability and simplified management of data on complex storage networks. CommVault's exclusive single-platform architecture gives companies unp...
"ciqada is a combined platform of hardware modules and server products that lets people take their existing devices or new devices and lets them be accessible over the Internet for their users," noted Geoff Engelstein of ciqada, a division of Mars International, in this SYS-CON.tv interview at @ThingsExpo, held June 9-11, 2015, at the Javits Center in New York City.
Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? In this Power Panel at DevOps Summit, moderated by Jason Bloomberg, the leading expert on architecting agility for the enterprise and president of Intellyx, panelists peeled away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud environment, and we must architect and code accordingly. At the very least, you'll have no problem fillin...
The 17th International Cloud Expo has announced that its Call for Papers is open. 17th International Cloud Expo, to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, APM, APIs, Microservices, Security, Big Data, Internet of Things, DevOps and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportunity. Submit your speaking proposal today!
The 5th International DevOps Summit, co-located with 17th International Cloud Expo – being held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Among the proven benefits, DevOps is corr...
Internet of Things (IoT) will be a hybrid ecosystem of diverse devices and sensors collaborating with operational and enterprise systems to create the next big application. In their session at @ThingsExpo, Bramh Gupta, founder and CEO of robomq.io, and Fred Yatzeck, principal architect leading product development at robomq.io, discussed how choosing the right middleware and integration strategy from the get-go will enable IoT solution developers to adapt and grow with the industry, while at the same time reduce Time to Market (TTM) by using plug and play capabilities offered by a robust IoT ...
The basic integration architecture, as defined by ESBs, hasn’t changed for more than a decade. Most cloud integration providers still rely on an ESB architecture and their proprietary connectors. As a result, enterprise integration projects suffer from constraints of availability and reliability of these connectors that are not re-usable across other integration vendors. However, the rapid adoption of APIs and almost ubiquitous availability of APIs amongst most SaaS and Cloud applications are rapidly redefining traditional integration approaches and their reliance on proprietary connectors. ...