CSC/ECE 517 Fall 2009/wiki1b 9 ad

Scaffold

Scaffolding is a meta-programming method of building database-backed software applications. It is a technique that allows a programmer to quickly generate a skeleton interface that allows the user to perform basic CRUD ( Create Read Update Delete) operations on the application's database. The auto-generated interface can then be modified to perform more powerful tasks.

Why was dynamic scaffolding removed in Rails 2?

Dynamic Scaffolding of Rails 1.x was replaced by a generator of scaffolds in Rails 2.

David Heinemeier Hansson responding to a new rails developer on a Ruby forum said "Dynamic Scaffolding didn't really help people learn about Rails or give them a way to modify the generated interface, so we killed it.".

In dynamic scaffolding when the line scaffold :model_name is added to the controller ruby automatically generates the appropriate interfaces at run time. Since, scaffolding is implemented on the fly the programmer cannot easily modify and customize the interfaces.Therefore, dynamic scaffolding was removed in Rails 2 though it is still available as a plugin.

Pros and cons of Dynamic Scaffolding

Pros

1. The biggest advantage of Dynamic scaffolding is that it allows the programmer to extend and modify the database schema without worrying about reflecting those changes in the interface. The user interface automatically updates to keep up with the changes.
2. The code to generate scaffolds dynamically is simple in most frameworks and a lot is accomplished in a single line of code.

Cons

1. The biggest disadvantage of Dynamic scaffolding is that the programmer cannot see whats going on. Since all the interfaces are generated on the fly, the code is hidden; this could be especially disadvantageous to someone who is trying to learn Rails.
2. The dynamic nature of generating scaffolds makes the behaviour of the application a little unpredictable.
3. It is difficult to modify or customize the scaffold code since it is generated at run time.

Scaffolding in frameworks for other languages

Many other languages such as Java, .NET, PHP, Python have frameworks that have adapted scaffolding. Some of the frameworks that have adapted scaffolding are CakePHP, Codelgniter, Symphony and Yii for PHP, Django for Python, MonoRail for .Net and Seam for Java.

CakePHP for PHP

Scaffolding in CakePHP is

Django for Python

Django is an open source web application framework, written in Python, which follows the model-view-controller architectural pattern. Just like Rails, Django aims at providing the concept of 'DRY' and extensive reusability. With regard to scaffolding, once the models are defined, Django can automatically create a professional and production ready administrative interface -- a Web site that lets authenticated users add, change and delete objects.

The framework offers role-based authentication and also one does not have to deal with creating backend interfaces just to manage content. It uses generic views to help automate CRUD operations that rails scaffold provides, minus the html generation.

When compared with Rails, Rails is slightly faster because of its scaffolding feature which generates some html as well as the model-interaction code, which you can then tweak to your own liking. The one downside is Rails doesn't provide its own user auth system, but there are plenty of plugins that implement that. Customization of the generic views in Django is possible but you kind of have to hack around the blackbox or implement it yourself.

Resources

• Scaffold
• Scaffolding in Rails