We've talked previously about how the controller is responsible for deciding which view files to render to the user. Read the Rendering Content chapter if you need to refresh your memory about that topic.
In this chapter, we'll explain exactly where to place these files and what to put in them.
In the simplest case, your controller action (typically a function inside your controller CFC file) will have a view file associated with it. As explained in the Rendering Content chapter, this file will be included automatically at the end of the controller action code. So if you're running the
show action in the
blog controller, for example, Wheels will include the
Some rules can be spotted here:
- All view files live in the
- Each controller gets a subfolder named after it in the
- The view file to include is just a regular
.cfmfile named after the action.
For creating standard pages, your work process will likely consist of the following steps:
- Create the controller action (a function in the controller CFC file).
- Create the corresponding view file for it (a
.cfmfile in the controller's view folder).
There can be some exceptions to this process though, so let's go through some possible scenarios.
Not all controller actions need a corresponding view file. Consider the case where you process a form submission. To make sure it's not possible for the user to refresh the page and cause multiple submissions, you may choose to perform the form processing and then send the user directly to another page using the redirectTo() function.
Sometimes you want the controller action to render the view file for a different action than the one currently executing. This is especially common when your application processes a form and the user makes an input error. In this case, you'll probably choose to have your application display the same form again for correction.
In this case, you can use the renderPage() function and specify a different action in the
action argument (which will include the view page for that action but not run the controller code for it).
Sometimes it's useful to have a view file that can be called from several controller actions. For these cases, you'll typically call renderPage() with the
When using the
template argument, there are specific rules that Wheels will follow in order to locate the file you want to include:
- If the template argument starts with the
/character, Wheels will start searching from the root of the
renderPage(template="/common/page")will include the
- If it contains the
/character elsewhere in the string, the search will start from the controller's view folder. Example:
renderPage(template="misc/page")will include the
views/blog/misc/page.cfmfile if we're currently in the
- In all other cases (i.e. when the template argument does not contain the
/character at all), Wheels will just assume the file is in the controller's view folder and try to include it. Example:
renderPage(template="something")will include the
views/blog/something.cfmfile if we're currently in the
Also note that both
renderPage(template="thepage.cfm") work fine. But most of the time, Wheels developers will tend to leave out the
In addition to this normal code that you'll see in most ColdFusion applications—whether they are made for a framework or not—Wheels also gives you some nice constructs to help keep your code clean. The most important ones of these are Layouts , Partials, and Helpers.
When writing your view code, you will have access to the variables you have set up in the controller file. The idea is that the variables you want to access in the view should be set unscoped (or in the
variables scope if you prefer to set it explicitly) in the controller so that they are available to the view template.
In addition to the variables you have set yourself, you can also access the
params struct. This contains anything passed in through the URL or with a form. If you want to follow MVC rules more closely though, we recommend only accessing the
params struct in the controller and then setting new variables for the information you need access to in the view.
The most important thing to remember when creating your view is to be careful not to put too much code in there. Avoid code dealing with the incoming request (this can be moved to the controller) and code containing business logic (consider moving this to a model). If you have view-related code but too much of it, it may be beneficial to break it out into a helper or a partial.
A view's job is also to clean up and format the values provided by the controller before being displayed. This is especially important when content from a data source is not HTML-escaped.
For example, if the view is to display the
title column from a query object called
posts, it should escape HTML special characters:
<ul> <cfoutput query="posts"> <li>#HtmlEditFormat(posts.title)#</li> </cfoutput> </ul>