Resultant Systems

We’re on Page 52 of Head First Rails, and we need to create a custom Controller and View.

I’m going to keep following the book, but there is a great tutorial that covers the same ideas over on the CFWheels website.

Convention Rules!  CFWheels has conventions for almost everything. As long as you follow the conventions, things just work naturally.

For example, look at a URL like this http://localhost/ads/show/5. CFWheels will automatically interpret this to run the show function in the ads controller. The number 5 is passed as a “key”.

Before I keep going, I have to touch on URL rewriting. The URL I just used as an example will only work if your server supports full URL rewriting. I’m using the ColdFusion development server, and it only offers “partial” URL rewriting. So, I have to use a URL like this: http://localhost/index.cfm/ads/show/5. Notice that index.cfm has to be inserted in the URL!

You can also specify the Controller and Action like this: http://localhost/index.cfm?controller=ads&action=show&key=5. Doing it this way will always work. It bypasses routes and any server URL rewriting problems. You might want to just use this form of URL while you are learning or if you are debugging a problem.

In any case, the idea is to run the show function in the ads controller. CFWheels will look for Ads.cfc in the controller folder, and will look for the show function inside Ads.cfc.

Then, it will run the show function and load the view. It will expect there to be a view file in /views/ads named show.cfm to match the function you called.

But, guess what? If you don’t create the Ads.cfc controller, CFWheels, will still try to run the view. Normally, you’ll want the controller to get some data for you, but if not, you could skip the controller altogether.

Here’s my controller code for /controllers/Ads.cfc:

[cf]
<cfcomponent extends="Controller">

<cffunction name="index">

</cffunction>

<cffunction name="show">

</cffunction>

</cfcomponent>
[/cf]

Later, we’ll add some functionality to the controller, but I’m following the book. And, for now, the only two actions we need are index and show.

At this point, you could try to go to http://localhost/index.cfm?controller=ads&action=show&key=5. But, you’d get a Wheels error because there is no view file.

Here’s my view code for /views/ads/show.cfm:

[cf]
<p><b>Name:</b></p>
<p><b>Description:</b></p>
<p><b>Price:</b></p>
<p><b>Seller Id:</b></p>
<p><b>Email:</b></p>
<p><img src=""/></p>
[/cf]

I know, this doesn’t do much either, but we’ll add on. Be Patient!

Now, if you go to http://localhost/index.cfm?controller=ads&action=show&key=5, you’ll see the lovely static view file you just created.

Next time, we’ll look at routes some more, and eventually, we’ll actually make this app work.

Clarke Bishop CFWheels, ColdFusion CFWheels

Continuing the series on using Head First Rails to learn CFWheels, lets move on to Chapter 2 — Beyond Scaffolding. We are going to create the MeBay application!

Starting on Page 45 in Head First Rails …

Whether we use scaffolding or not, we still have to create the database. In Rails, you do this with the script/generate model command and then running rake. But, in CFWheels, it’s easiest to just use SQL and create the database directly. Here is some mySQL code to create the needed ads table.

[sql]

CREATE TABLE `ads` (
`id` INTEGER PRIMARY KEY NOT NULL auto_increment,
`name` varchar(255),
`description` text,
`price` decimal,
`seller_id` integer,
`email` varchar(255),
`img_url` varchar(255),
`created_at` datetime,
`updated_at` datetime
);
[/sql]

Later on, we’ll want to populate the table with some sample data, so let me go ahead and show the full SQL that creates the table and adds the test data:

[sql]
DROP TABLE IF EXISTS `ads` ;
CREATE TABLE `ads` (
`id` INTEGER PRIMARY KEY NOT NULL auto_increment,
`name` varchar(255),
`description` text,
`price` decimal,
`seller_id` integer,
`email` varchar(255),
`img_url` varchar(255),
`created_at` datetime,
`updated_at` datetime
);
INSERT INTO `ads` VALUES(1,’Typewriter’,'Old manual typewriter. Many years useful service. Works best with a bottle next to it.’,71.95,54,’dhammett@email.com’,'http://homepage.mac.com/david_griffiths/typewriter.png’,”,”);
INSERT INTO `ads` VALUES(2,’Football’,'Some strings frayed.’,74.02,45,’marty@googlemail.com’,'http://www.freefever.com/freeclipart/clipart/football2.gif’,”,”);
INSERT INTO `ads` VALUES(3,’Moosehead’,'Slightly moth-eaten. One of the antlers is broken and there’’s a strange buzzing sound behind the eyes…’,2978.25,56,’kathy@hotmail.com’,'http://saloon.javaranch.com/ubb/moosefly.gif’,”,”);
INSERT INTO `ads` VALUES(4,’Desk’,'Milk desk – go…’,4800,123,’andy@allmail….’,'http://picasaweb.goog…’,”,”);
INSERT INTO `ads` VALUES(5,’Door curtain’,'Beaded door cu…’,11,773,’dawn@hotmail….’,'http://www.freewebsit…’,”,”);
INSERT INTO `ads` VALUES(6,’Apple Newton’,'Still works! M…’,25,2,’ahertz@differ…’,'http://www.differnet….’,”,”);
INSERT INTO `ads` VALUES(7,’Sinclair C5′,’Battery flat t…’,372.06,346,’clive@sinclai…’,'http://www.ebay.com/w…’,”,”);
INSERT INTO `ads` VALUES(8,’Edsel’,'Never used aut…’,355,755,’bing@badabing…’,'http://pages.google.c…’,”,”);
INSERT INTO `ads` VALUES(37,’Diamond’,'203.4 carats, grade D pear cut diamond. Low price for quick sale. Owner leaving the country.’,1000000,5234,’pink@panther.com’,'http://’,”,”);
[/sql]

It’s easy enough to manually create the Model, but for convenience, let’s use the scaffolding plugin anyway.

Click the Scaffold link at the bottom of any CFWHeels page –  In the debug section, next to Plugins. Then, on the scaffold page, enter ad as the Object name, select Model from the Type drop down, and click Generate. Remember, the table is named ads (plural with an “s”), but the the model is named ad (singular).

Now, open /models/Ad.cfc. You’ll see something that looks like:

[cf]
<cfcomponent extends="Model">

<!— All initialization related tasks are done in the "init" function which is run the first time the model is requested. —>
<cffunction name="init">
</cffunction>

</cfcomponent>
[/cf]

That’s all it takes to create a model! Your model must extend Model.cfc — That’s where all the CFWheels goodness happens. Other than that, all you need is an init function. Later on, you can use the init function to add extra capabilities, but for now, all that’s needed is a blank init function!

Clarke Bishop CFWheels, ColdFusion CFWheels