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
Since 2008 and for the first time in history, more than half of humans live in urban areas, urging cities to become “smart.” Today, cities can leverage the wide availability of smartphones combined with new technologies such as Beacons or NFC to connect their urban furniture and environment to create citizen-first services that improve transportation, way-finding and information delivery. In her session at @ThingsExpo, Laetitia Gazel-Anthoine, CEO of Connecthings, will focus on successful use cases.
One of the biggest impacts of the Internet of Things is and will continue to be on data; specifically data volume, management and usage. Companies are scrambling to adapt to this new and unpredictable data reality with legacy infrastructure that cannot handle the speed and volume of data. In his session at @ThingsExpo, Don DeLoach, CEO and president of Infobright, will discuss how companies need to rethink their data infrastructure to participate in the IoT, including: Data storage: Understanding the kinds of data: structured, unstructured, big/small? Analytics: What kinds and how responsiv...
Building low-cost wearable devices can enhance the quality of our lives. In his session at Internet of @ThingsExpo, Sai Yamanoor, Embedded Software Engineer at Altschool, provided an example of putting together a small keychain within a $50 budget that educates the user about the air quality in their surroundings. He also provided examples such as building a wearable device that provides transit or recreational information. He then reviewed the resources available to build wearable devices at home including open source hardware, the raw materials required and the options available to power s...
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...
DevOps tends to focus on the relationship between Dev and Ops, putting an emphasis on the ops and application infrastructure. But that’s changing with microservices architectures. In her session at DevOps Summit, Lori MacVittie, Evangelist for F5 Networks, will focus on how microservices are changing the underlying architectures needed to scale, secure and deliver applications based on highly distributed (micro) services and why that means an expansion into “the network” for DevOps.
How do APIs and IoT relate? The answer is not as simple as merely adding an API on top of a dumb device, but rather about understanding the architectural patterns for implementing an IoT fabric. There are typically two or three trends: Exposing the device to a management framework Exposing that management framework to a business centric logic Exposing that business layer and data to end users. This last trend is the IoT stack, which involves a new shift in the separation of what stuff happens, where data lives and where the interface lies. For instance, it's a mix of architectural styles ...
The 3rd International @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 – is now accepting Hackathon proposals. Hackathon sponsorship benefits include general brand exposure and increasing engagement with the developer ecosystem. At Cloud Expo 2014 Silicon Valley, IBM held the Bluemix Developer Playground on November 5 and ElasticBox held the DevOps Hackathon on November 6. Both events took place on the expo floor. The Bluemix Developer Playground, for developers of all levels, highlighted the ease of use of...
We’re no longer looking to the future for the IoT wave. It’s no longer a distant dream but a reality that has arrived. It’s now time to make sure the industry is in alignment to meet the IoT growing pains – cooperate and collaborate as well as innovate. In his session at @ThingsExpo, Jim Hunter, Chief Scientist & Technology Evangelist at Greenwave Systems, will examine the key ingredients to IoT success and identify solutions to challenges the industry is facing. The deep industry expertise behind this presentation will provide attendees with a leading edge view of rapidly emerging IoT oppor...
Connected devices and the Internet of Things are getting significant momentum in 2014. In his session at Internet of @ThingsExpo, Jim Hunter, Chief Scientist & Technology Evangelist at Greenwave Systems, examined three key elements that together will drive mass adoption of the IoT before the end of 2015. The first element is the recent advent of robust open source protocols (like AllJoyn and WebRTC) that facilitate M2M communication. The second is broad availability of flexible, cost-effective storage designed to handle the massive surge in back-end data in a world where timely analytics is e...
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core of our infrastructures. At the same time, we have old approaches made new again like micro-services...
SYS-CON Events announced today that Gridstore™, the leader in hyper-converged infrastructure purpose-built to optimize Microsoft workloads, 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. Gridstore™ is the leader in hyper-converged infrastructure purpose-built for Microsoft workloads and designed to accelerate applications in virtualized environments. Gridstore’s hyper-converged infrastructure is the industry’s first all flash version of HyperConverged Appliances that include both compute and storag...
For years, we’ve relied too heavily on individual network functions or simplistic cloud controllers. However, they are no longer enough for today’s modern cloud data center. Businesses need a comprehensive platform architecture in order to deliver a complete networking suite for IoT environment based on OpenStack. In his session at @ThingsExpo, Dhiraj Sehgal from PLUMgrid will discuss what a holistic networking solution should really entail, and how to build a complete platform that is scalable, secure, agile and automated.
The industrial software market has treated data with the mentality of “collect everything now, worry about how to use it later.” We now find ourselves buried in data, with the pervasive connectivity of the (Industrial) Internet of Things only piling on more numbers. There’s too much data and not enough information. In his session at @ThingsExpo, Bob Gates, Global Marketing Director, GE’s Intelligent Platforms business, to discuss how realizing the power of IoT, software developers are now focused on understanding how industrial data can create intelligence for industrial operations. Imagine ...
Hadoop as a Service (as offered by handful of niche vendors now) is a cloud computing solution that makes medium and large-scale data processing accessible, easy, fast and inexpensive. In his session at Big Data Expo, Kumar Ramamurthy, Vice President and Chief Technologist, EIM & Big Data, at Virtusa, will discuss how this is achieved by eliminating the operational challenges of running Hadoop, so one can focus on business growth. The fragmented Hadoop distribution world and various PaaS solutions that provide a Hadoop flavor either make choices for customers very flexible in the name of opti...
In the consumer IoT, everything is new, and the IT world of bits and bytes holds sway. But industrial and commercial realms encompass operational technology (OT) that has been around for 25 or 50 years. This grittier, pre-IP, more hands-on world has much to gain from Industrial IoT (IIoT) applications and principles. But adding sensors and wireless connectivity won’t work in environments that demand unwavering reliability and performance. In his session at @ThingsExpo, Ron Sege, CEO of Echelon, will discuss how as enterprise IT embraces other IoT-related technology trends, enterprises with i...
The true value of the Internet of Things (IoT) lies not just in the data, but through the services that protect the data, perform the analysis and present findings in a usable way. With many IoT elements rooted in traditional IT components, Big Data and IoT isn’t just a play for enterprise. In fact, the IoT presents SMBs with the prospect of launching entirely new activities and exploring innovative areas. CompTIA research identifies several areas where IoT is expected to have the greatest impact.
Wearable devices have come of age. The primary applications of wearables so far have been "the Quantified Self" or the tracking of one's fitness and health status. We propose the evolution of wearables into social and emotional communication devices. Our BE(tm) sensor uses light to visualize the skin conductance response. Our sensors are very inexpensive and can be massively distributed to audiences or groups of any size, in order to gauge reactions to performances, video, or any kind of presentation. In her session at @ThingsExpo, Jocelyn Scheirer, CEO & Founder of Bionolux, will discuss ho...
Every day we read jaw-dropping stats on the explosion of data. We allocate significant resources to harness and better understand it. We build businesses around it. But we’ve only just begun. For big payoffs in Big Data, CIOs are turning to cognitive computing. Cognitive computing’s ability to securely extract insights, understand natural language, and get smarter each time it’s used is the next, logical step for Big Data.
We are reaching the end of the beginning with WebRTC, and real systems using this technology have begun to appear. One challenge that faces every WebRTC deployment (in some form or another) is identity management. For example, if you have an existing service – possibly built on a variety of different PaaS/SaaS offerings – and you want to add real-time communications you are faced with a challenge relating to user management, authentication, authorization, and validation. Service providers will want to use their existing identities, but these will have credentials already that are (hopefully) i...
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 20 years ago.