What good is having code running inside your templates, anyway?
The MVC pattern is a wonderful thing. It helps developers design resilient, testable, and well structured applications. Almost every web framework is centered around MVC (Phoenix, withstanding). So why, then, do most of these frameworks allow you to embed code directly into the view layer?
View layers tend to allow code because developers immediately run into problems when they need to iterate over a list of items. And, let’s face it, with a CRUD operation, that’s one of the first things you do. One can justify leaving code in the view layer, because it adds flexibility. The last thing you want is to have your view templates be a limiting factor in your application.
Mexico Insurance Online’s application, however, is a solid exception to that rule. We have some… substantial resellers who sell directly to their customers through the application. Those resellers demand an entirely custom view. From the font on a <label> tag to which fields appear on a given form, everything can, and will, be customized. To that end, a bit of rigidity actually makes life easier, let me show you.
Curly Templates is what Mexico Insurance Online’s application will use for the view layer in our rebuild project. The magic of Curly lies in its Presenter classes:
class Posts::CommentPresenter < Curly::Presenter
presents :comment
def replies
content_tag :div do
for reply in @comment.replies do
render 'reply', reply
end
end
end
end
A single presenter, such as the above, can be shared across multiple views. If a resellers needs to customize the way that replies are presented, then an alternative to the _reply.html.curly file can be created, leaving the rest of the view un-touched.
Had this view been implemented with the ERB syntax that comes with Ruby on Rails, then both the main application and the custom view for the reseller would need the loop code. Given that Mexico Insurance Online has 296 white-label templates at the moment, this means there would be 296 loops to update if something changed.
This may seem like something simple, but the white-labeling provided by Mexico Insurance Online is crucial to its continued success.