Click here to close now.

Welcome!

You will be redirected in 30 seconds or close now.

ColdFusion Authors: Yakov Fain, Maureen O'Gara, Nancy Y. Nee, Tad Anderson, Daniel Kaar

Related Topics: ColdFusion

ColdFusion: Article

Encapsulating Recordsets

Do you need getters and setters for your recordsets?

One of the first things that you encounter when moving to object-oriented (OO) programming are beans. Beans are simple representations of a business object (like a user or a product) that hide all of the information stored in the bean behind methods (functions) for getting and setting the information (called, unsurprisingly, getters and setters).

Typically, if you want to display a product view screen, you'll get the product information from the database, load the resulting query recordset into a bean and then, instead of displaying the variables from the query, call the methods from the bean. In the past your product view may have looked like this:

<cfoutput query="GetProduct">
    #Title#<br />
    $#Price#<br /><br />
</cfoutput>

With a bean, the product view will change to the following:

<cfoutput>
#Product.get("Title")#<br />
$#Product.get("Price")#<br /><br />
</cfoutput>

The only difference is that you are calling a "get" method that hides (encapsulates) the way the title and the price are retrieved, but this small difference can have a big impact on the maintainability of your code. (The sharp eyed among you will have noticed that I'm using a generic getter. The sidebar explains why this might be a good idea for you to consider).

Why Encapsulate?
Object-oriented programming is all about writing more maintainable code. Many Object Oriented patterns take longer to code initially than a traditional procedural approach, but they are easier to maintain. Given that we tend to spend much more time maintaining than developing applications, this is usually a worthwhile trade-off.

The benefit of encapsulating business object attributes behind getters and setters is that if the logic required to calculate (or save) the attribute changes, you only have to change the code in one place. Let's say that the product price is calculated based on a sale price. In the past you might have put that logic right into the product view:

<cfoutput query="GetProduct">
    #Title#<br />
    $<cfif SalePrice>#SalePrice#<cfelse>#Price#</cfif><br /><br />
</cfoutput>

The problem is, there may also be a product list screen, a product search results screen, and the cart and checkout may also need to know the price of a product, so if you changed the way you calculated the price, you would have to remember to make that change in five places. Even worse, there is the risk that you might forget to update one of the screens, so products displayed on the search screen would display a different price than when added to the basket.

With getters and setters encapsulating the logic, there would be no change at all to the display screens. They would still be:

<cfoutput>
#Product.get("Title")#<br />
$#Product.get("Price")#<br /><br />
</cfoutput>

The only difference is that you would change the getPrice() custom method within the product object to be something like:

<cffunction name="getPrice" returntype="numeric" access="public"
output="no" hint="I return the price to display and charge for the product">
    <cfset var Local = structNew()>
    <cfif variables.get("SalePrice")>
      <cfset Local.ReturnValue = variables.get("SalePrice")>
    <cfelse>
      <cfset Local.ReturnValue = variables.Price>
    </cfif>
    <cfreturn Local.ReturnValue>
</cffunction>

So, encapsulation of getters and setters using beans is a key element of Object Oriented programming, and it is a best practice that most OO developers would use most of the time. So, what happens when we have more than one user or product or article?

The Performance Problem
In Java, this would be easy. You would take your recordset, use it to create a collection of objects (one for each record), and you would still have all of the benefits of encapsulated getting and setting of properties. Unfortunately, in ColdFusion, object creation is expensive (in terms of performance). Creating a large number of objects as part of every page load can substantially affect the performance of a ColdFusion script.

Because of this, a lot of ColdFusion developers currently use recordsets for displaying their lists, losing all of the benefits of encapsulation. If they want to change the way the price is calculated for a product list, they either need to push back the price calculation onto the database; write a script in their service object to loop through the query implementing any custom data transformations; or replicate their business logic all over their list screens.

Introducing the Iterating Business Object
The iterating business object (IBO) is a simple solution to the problem of encapsulating access to getters and setters for recordsets without sacrificing performance. It is implemented as a base class that your business objects can extend. As well as providing generic getters and setters, it can also load itself with a query, and it provides a basic set of iterating methods (first(), next(), and isLast()) for looping through the recordset.

The IBO allows you to get all of the benefits of encapsulated getting and setting of attributes - whether you are working with a single object or a collection of them. It also allows you to use exactly the same code for both your single objects and object collections. For example, it really doesn't matter whether you are viewing a single product on a product detail page or a list of products matching a search query. If you want to display the price for the product, you want to use the same business logic to calculate it in both cases. With an IBO, you always load the same object up with the results from your query, and you can maintain all of your getter and setter calculations in that one object. In addition, you are only instantiating a single object per page view, so the performance hit is nominal. You can see the code for a simple IBO in Listing 1.

Using the Iterating Business Object
When you are using the IBO to display a single record, it is exactly the same as using a bean:

<cfoutput>
    #Product.get("Title")#<br />
    $#Product.get("Price")#<br /><br />
</cfoutput>

If you want to display a list of records, it is almost as easy. You take the same basic display code and just wrap it with a loop based on the iterating methods of the object:

<cfset Product.first()>
<cfloop condition="NOT #Product.isLast()#">
<cfoutput>
    #Product.get("Title")#<br />
    $#Product.get("Price")#<br /><br />
</cfoutput>
<cfset Product.Next()>
</cfloop>

Improving the Object
Previously I showed an example of a custom getter for calculating the price of a product. If there was a sale price, it displayed that, otherwise it just accessed the variables scope to get the price. Well, that works for a single record, but if there are multiple records (as with the IBO), the actual code to access a particular record would be more like:

<cfset Local.ReturnValue = variables.Data[variables.IteratorCount].Price>

Where the variables.IteratorCount is a pointer to the current record within the recordset being displayed. This isn't "wrong", but over time all of the custom methods would have to include this code, and if I ever decided to change the structure of the data storage within the variables scope, all of those methods would have to be rewritten.

To encapsulate that change, I added one more pair of generic methods to the base IBO: access() and mutate(). Accessors and mutators are alternate terms for getters and setters, but these methods are private and are only to be used by the customer getters and setters to access the underlying data structure, so if I ever wished to change the structure, I would only have to change those two methods. Below is simplified code for the access() method (the full code is available in Listing 1):

<cffunction name="access" returntype="any" access="private" output="no"
hint="I encapsulate access to the attribute values within this object,
accepting an attribute name and returning the appropriate attribute value.">
    <cfargument name="AttributeName" type="string" required="yes"
    hint="I am the name of the attribute to return the value for">
    <cfset var Local = structNew()>
<cfset Local.ReturnValue = variables.Data[variables.IteratorCount][arguments.AttributeName] >
    <cfreturn Local.ReturnValue>
</cffunction>

With this in place, we can now simplify the data access in the custom methods to just:

<cfset Local.ReturnValue = variables.access("Price")>

Conclusion
I have used the IBO on a number of production projects over the last couple of months. One project in particular required almost daily changes to the (very complex) object model as we continually added new attributes and changed the rules for calculating existing attributes. I found the application extremely easy to maintain and it is now in production, powering over 20 different sites and performing very well under load.

If you don't have any calculations for getting or setting any of your object attributes and really don't expect any in the future, any kind of encapsulation is overkill, and you would be better just to display using recordsets and cfoutput - for one record or for many. If you do have calculated fields, give the IBO a try and see how it works for your projects.

More Stories By Peter Bell

Peter Bell is CEO/CTO of SystemsForge (http://ww.systemsforge.com) and helps Web designers to increase their profits and build a residual income by generating custom web applications - in minutes, not months. An experienced entrepreneur and software architect with fifteen years of business experience, he lectures and blogs extensively on application generation and ColdFusion design patterns (http://www.pbell.com).

Comments (2) View Comments

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.


Most Recent Comments
Peter Bell 01/02/07 07:19:46 PM EST

Hi Michael,

Good catch! That was indeed a little messy and is something I plan to clean up later this month. if you're interested, I'll be reposting code on my Blog. I'm probably going to use isDone(), but will take a little time to look at some other iterators to see what syntax is most popular.

Michael Long 11/26/06 07:49:10 PM EST

Could just be me, but I'd expect a function named "isLast" to return true if I'm actually on the last record. Which would in turn lead to an off-by-one error, as the loop would terminate early.

Better, perhaps, would be isEOF, or isDone, either of which would be true if the current record count is greater than the actual record count.

@ThingsExpo Stories
SYS-CON Events announced today that Cisco, the worldwide leader in IT that transforms how people connect, communicate and collaborate, has been named “Gold Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Cisco makes amazing things happen by connecting the unconnected. Cisco has shaped the future of the Internet by becoming the worldwide leader in transforming how people connect, communicate and collaborate. Cisco and our partners are building the platform for the Internet of Everything by connecting the...
Temasys has announced senior management additions to its team. Joining are David Holloway as Vice President of Commercial and Nadine Yap as Vice President of Product. Over the past 12 months Temasys has doubled in size as it adds new customers and expands the development of its Skylink platform. Skylink leads the charge to move WebRTC, traditionally seen as a desktop, browser based technology, to become a ubiquitous web communications technology on web and mobile, as well as Internet of Things compatible devices.
SYS-CON Events announced today that robomq.io will exhibit at SYS-CON's @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. robomq.io is an interoperable and composable platform that connects any device to any application. It helps systems integrators and the solution providers build new and innovative products and service for industries requiring monitoring or intelligence from devices and sensors.
SYS-CON Media announced today that @WebRTCSummit Blog, the largest WebRTC resource in the world, has been launched. @WebRTCSummit Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @WebRTCSummit Blog can be bookmarked ▸ Here @WebRTCSummit conference site can be bookmarked ▸ Here
Docker is an excellent platform for organizations interested in running microservices. It offers portability and consistency between development and production environments, quick provisioning times, and a simple way to isolate services. In his session at DevOps Summit at 16th Cloud Expo, Shannon Williams, co-founder of Rancher Labs, will walk through these and other benefits of using Docker to run microservices, and provide an overview of RancherOS, a minimalist distribution of Linux designed expressly to run Docker. He will also discuss Rancher, an orchestration and service discovery platf...
Sonus Networks introduced the Sonus WebRTC Services Solution, a virtualized Web Real-Time Communications (WebRTC) offer, purpose-built for the Cloud. The WebRTC Services Solution provides signaling from WebRTC-to-WebRTC applications and interworking from WebRTC-to-Session Initiation Protocol (SIP), delivering advanced real-time communications capabilities on mobile applications and on websites, which are accessible via a browser.
SYS-CON Events announced today that Aria Systems, the leading innovator in recurring revenue, has been named “Bronze Sponsor” of SYS-CON's @ThingsExpo, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Proven by the world’s most demanding enterprises, including AAA NCNU, Constant Contact, Falck, Hootsuite, Pitney Bowes, Telekom Denmark, and VMware, Aria helps enterprises grow their recurring revenue businesses. With Aria’s end-to-end active monetization platform, global brands can get to market faster with a wider variety of products and services, while maximizin...
SYS-CON Events announced today that Vitria Technology, Inc. will exhibit at SYS-CON’s @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Vitria will showcase the company’s new IoT Analytics Platform through live demonstrations at booth #330. Vitria’s IoT Analytics Platform, fully integrated and powered by an operational intelligence engine, enables customers to rapidly build and operationalize advanced analytics to deliver timely business outcomes for use cases across the industrial, enterprise, and consumer segments.
SYS-CON Events announced today that Akana, formerly SOA Software, has been named “Bronze Sponsor” of SYS-CON's 16th International Cloud Expo® New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Akana’s comprehensive suite of API Management, API Security, Integrated SOA Governance, and Cloud Integration solutions helps businesses accelerate digital transformation by securely extending their reach across multiple channels – mobile, cloud and Internet of Things. Akana enables enterprises to share data as APIs, connect and integrate applications, drive part...
After making a doctor’s appointment via your mobile device, you receive a calendar invite. The day of your appointment, you get a reminder with the doctor’s location and contact information. As you enter the doctor’s exam room, the medical team is equipped with the latest tablet containing your medical history – he or she makes real time updates to your medical file. At the end of your visit, you receive an electronic prescription to your preferred pharmacy and can schedule your next appointment.
The WebRTC Summit 2014 New York, to be held June 9-11, 2015, at the Javits Center in New York, NY, announces that its Call for Papers is open. Topics include all aspects of improving IT delivery by eliminating waste through automated business models leveraging cloud technologies. WebRTC Summit is co-located with 16th International Cloud Expo, @ThingsExpo, Big Data Expo, and DevOps Summit.
SYS-CON Events announced today that Solgenia will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY, and the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Solgenia is the global market leader in Cloud Collaboration and Cloud Infrastructure software solutions. Designed to “Bridge the Gap” between Personal and Professional Social, Mobile and Cloud user experiences, our solutions help large and medium-sized organizations dr...
SYS-CON Events announced today that Liaison Technologies, a leading provider of data management and integration cloud services and solutions, has been named "Silver Sponsor" of SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York, NY. Liaison Technologies is a recognized market leader in providing cloud-enabled data integration and data management solutions to break down complex information barriers, enabling enterprises to make smarter decisions, faster.
The 3rd International Internet of @ThingsExpo, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - 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 20 years ago.
SYS-CON Events announced today that CommVault has been named “Bronze Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY, and the 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 sim...
Cloud is not a commodity. And no matter what you call it, computing doesn’t come out of the sky. It comes from physical hardware inside brick and mortar facilities connected by hundreds of miles of networking cable. And no two clouds are built the same way. SoftLayer gives you the highest performing cloud infrastructure available. One platform that takes data centers around the world that are full of the widest range of cloud computing options, and then integrates and automates everything. Join SoftLayer on June 9 at 16th Cloud Expo to learn about IBM Cloud's SoftLayer platform, explore se...
SYS-CON Media announced today that 9 out of 10 " most read" DevOps articles are published by @DevOpsSummit Blog. Launched in October 2014, @DevOpsSummit Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. 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 development cycles that produce softw...
The list of ‘new paradigm’ technologies that now surrounds us appears to be at an all time high. From cloud computing and Big Data analytics to Bring Your Own Device (BYOD) and the Internet of Things (IoT), today we have to deal with what the industry likes to call ‘paradigm shifts’ at every level of IT. This is disruption; of course, we understand that – change is almost always disruptive.
Wearable technology was dominant at this year’s International Consumer Electronics Show (CES) , and MWC was no exception to this trend. New versions of favorites, such as the Samsung Gear (three new products were released: the Gear 2, the Gear 2 Neo and the Gear Fit), shared the limelight with new wearables like Pebble Time Steel (the new premium version of the company’s previously released smartwatch) and the LG Watch Urbane. The most dramatic difference at MWC was an emphasis on presenting wearables as fashion accessories and moving away from the original clunky technology associated with t...
The world's leading Cloud event, Cloud Expo has launched Microservices Journal on the SYS-CON.com portal, featuring over 19,000 original articles, news stories, features, and blog entries. DevOps Journal is focused on this critical enterprise IT topic in the world of cloud computing. Microservices Journal offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. Follow new article posts on Twitter at @MicroservicesE