Building Pages with a Page Object

I was reading through PHP and MySQL Web Development at the local bookstore the other night when I noticed that their example code for explaining object oriented concepts was a Page class that basically built a page based on its properties. While the concept of directly building the return code string by string is a little foreign to ColdFusion, I was very interested in the idea of an extensible Page object that could help me manage my applications. Read more to see what I came up with.

The Idea

The basic concept is that I want to come up with a Page class that I can reuse and extend to handle the basics of putting a page together. As an added bonus it should also probably be able to handle rendering different versions of the same page, such as when working with "themes" like in PHP. I'm going to have to limit myself from going beyond that for space reasons... my original list of specifications for this project had turned it into a mini-framework, and I think thats a little beyond the scope of what I'm looking to do right now.

Iteration One: The Basics

Ok, so the first thing I'm going to do is a very basic Page.cfc. It should act like my final version, but it wont be dynamic for now.

Page.cfc
<cfcomponent output="false">

    <cffunction name="Display" description="Displays the contents of the current page." access="public" output="false" returntype="string">
        <cfargument name="theme" type="string" required="false" />
        
        <cfsavecontent variable="local.returnValue">
<html>
    <head>
        <title>Test</title>
    </head>
    <body>
        Hello World!
    </body>
</html>
        </cfsavecontent>
        
        <cfreturn trim(local.returnValue) />
    </cffunction>

</cfcomponent>

Back in my root I drop in an index.cfm, and add the test code:

index.cfm
<cfscript>
    Page = CreateObject("Page");
    
    WriteOutput(Page.display());
</cfscript>

Run that and I get a simple hello world response. So far so good, but its not nearly dynamic enough.

Iteration 2: Make It Dynamic

The next step is to make this thing more dynamic since currently all of the content is static. This isn't really hard, I just added some variables scope properties to the Page.cfc, added the Getters and Setters, and updated display() to use those values:

Page.cfc
<cfcomponent output="false">

    <cfset variables.title = "Default" />
    <cfset variables.content = "" />

    <cffunction name="getTitle" access="public" output="false" returntype="string">
        <cfreturn variables.title />
    </cffunction>

    <cffunction name="setTitle" access="public" output="false" returntype="void">
        <cfargument name="title" type="string" required="true" />
        
        <cfset variables.title = arguments.title />
        
        <cfreturn />
    </cffunction>

    <cffunction name="getContent" access="public" output="false" returntype="string">
        <cfreturn variables.content />
    </cffunction>

    <cffunction name="setContent" access="public" output="false" returntype="void">
        <cfargument name="content" type="string" required="true" />
        
        <cfset variables.content = arguments.content />
        
        <cfreturn />
    </cffunction>

    <cffunction name="Display" description="Displays the contents of the current page." access="public" output="false" returntype="string">
        
        <cfsavecontent variable="local.returnValue">
<html>
    <head>
        <title><cfoutput>#getTitle()#</cfoutput></title>
    </head>
    <body>
        <cfoutput>#getContent()#</cfoutput>
    </body>
</html>
        </cfsavecontent>
        
        <cfreturn trim(local.returnValue) />
    </cffunction>

</cfcomponent>

Now my page isn't getting content by default, so I have to update my index.cfm as well.

index.cfm
<cfscript>
    Page = CreateObject("Page");
    
    Page.setContent("Hello from another world!");
    
    WriteOutput(Page.display());
</cfscript>

Ok, thats better, but I'm still putting my display code into my Page object, and what about those themes?

Iteration 3: Themes

For this iteration I want to pull the code for the display out of my Page.cfc into its own template, and I also want to make the whole thing work with themes so that its a little more dynamic. To do this I created a "themes/" folder in my root, and added two folders "red/" and "blue/" and added the following index.cfm files to them.

/themes/red/index.cfm
<html>
    <head>
        <title><cfoutput>#getTitle()#</cfoutput></title>
        <style>
            body {
                color: red;
            }
        </style>
    </head>
    <body>
        <h1>Red Theme</h1>
        <cfoutput>#getContent()#</cfoutput>
    </body>
</html>

/themes/blue/index.cfm
<html>
    <head>
        <title><cfoutput>#getTitle()#</cfoutput></title>
        <style>
            body {
                color: blue;
            }
        </style>
    </head>
    <body>
        <h1>Blue Theme</h1>
        <cfoutput>#getContent()#</cfoutput>
    </body>
</html>

Now I can switch between a red and a blue theme for my application, but I need a mechanism to control which theme to use, so I'll create an Application.cfc as well.

Application.cfc
<cfcomponent output="false">

    <cfset this.name = "PageFramework" />
    
    <cffunction name="OnApplicationStart">
    
        <cfset OnInitialization() />
    
    </cffunction>
    
    <cffunction name="OnRequestStart">
    
        <cfparam name="url.reinit" default="0" />
        
        <cfif url.reinit>
            <cflock scope="application" type="exclusive" timeout="10">
                <cfset OnInitialization() />
            </cflock>
        </cfif>
    
    </cffunction>

    <cffunction name="OnInitialization">
        
        <cfset application.theme = "red" />
        
    </cffunction>

</cfcomponent>

And finally, you'll beed to update your Page.cfc to work with this new setup:

Page.cfc
<cfcomponent output="false">

    <cfset variables.title = "Default" />
    <cfset variables.content = "" />
    <cfset variables.template = "index.cfm" />

    <cffunction name="getTitle" access="public" output="false" returntype="string">
        <cfreturn variables.title />
    </cffunction>

    <cffunction name="setTitle" access="public" output="false" returntype="void">
        <cfargument name="title" type="string" required="true" />
        
        <cfset variables.title = arguments.title />
        
        <cfreturn />
    </cffunction>

    <cffunction name="getContent" access="public" output="false" returntype="string">
        <cfreturn variables.content />
    </cffunction>

    <cffunction name="setContent" access="public" output="false" returntype="void">
        <cfargument name="content" type="string" required="true" />
        
        <cfset variables.content = arguments.content />
        
        <cfreturn />
    </cffunction>

    <cffunction name="Display" description="Displays the contents of the current page." access="public" output="false" returntype="string">
        <cfargument name="theme" type="string" required="false" default="#application.theme#" />
        
        <cfsavecontent variable="local.returnValue">
            <cfinclude template="/themes/#arguments.theme#/#variables.template#" />
        </cfsavecontent>
        
        <cfreturn trim(local.returnValue) />
    </cffunction>

</cfcomponent>

Now you should be able to switch your theme by updating your application.theme value and reinitalizing your application.

The End?

From here there is a lot more that can be done with this code, like adding in controller logic, handling the use of objects that extend Page.cfc (notice that I pulled the template out to a separate variable?), making the Getters and Setters work with a more dynamic data set so that more data can be passed through the Page object, and all kinds of things. This is all for now, but expect me to come back with some updates soon.

 

Comments

Oscar Arevalo's Gravatar Hey Jon,

Thats an interesting idea; I've been working on similar concept on a framework I'm developing called HomePortals. The framework is a bit bigger in scope, but the central premise is too having an abstraction of a page that can be assembled programmatically. So far documentation is a bit poor but I wrote a couple of blog posts showing how to assemble pages and the templating features.

<a href="http://www.oscararevalo.com/index.cfm/2009/3/23/Ho...;

<a href="http://www.oscararevalo.com/index.cfm/2009/3/27/Ho...;

<a href="http://www.oscararevalo.com/index.cfm/2009/5/8/So-...;

The code is open source so you are welcome to get it and play around with it.
Jon Hartmann's Gravatar @Oscar I poked around a little on the links you sent me and your framework does seem to have some similarities to what I've got here. I did notice in your example that your framework seems to build a page out of modules... I've looked at an approach like this in the past, but always ended up feeling like I was going to have to come up with a completely custom module for every element on the page. Did you encounter a situation like that as well?
Oscar Arevalo's Gravatar @jon, the way I minimized the amount of modules was by using a "module type". Each module that gets added to a page has a type. The type determines how the module is going to be interpreted. For example I have a type called "content" which just includes an existing HTML snippet on a page, another called "view" that does a cfinclude for dynamic functionality and another called "module" which is a full blown MVC widget framework for when I need to get funky. Then, each module instance also has other properties that tell that particular module type how to behave (i.e. a module of type view has also a property named href that is the path to the CF template to include)

Now, this implies that the content of the page (whatever that may be: html, cf, widgets) has to exist by itself outside the calling page. This allows the content to be easily reusable and not tied to a particular page.
Jon Hartmann, July 2011

I'm Jon Hartmann and I'm a Javascript fanatic, UX/UI evangelist and former ColdFusion master. I blog about mysterious error messages, user interface design questions, and all things baffling and irksome about programming for the web.

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