Ruby on Rails Don't Repeat Yourself (DRY)


Example

To help to maintain clean code, Rails follows the principle of DRY.

It involves whenever possible, re-using as much code as possible rather than duplicating similar code in multiple places (for example, using partials). This reduces errors, keeps your code clean and enforces the principle of writing code once and then reusing it. It is also easier and more efficient to update code in one place than to update multiple parts of the same code. Thus making your code more modular and robust.

Also Fat Model, Skinny Controller is DRY, because you write the code in your model and in the controller only do the call, like:

# Post model
scope :unpublished, ->(timestamp = Time.now) { where('published_at IS NULL OR published_at > ?', timestamp) } 


# Any controller
def index
    ....
    @unpublished_posts = Post.unpublished
    ....
end

def others
    ...
    @unpublished_posts = Post.unpublished
    ...
end

This also helps lead to an API driven structure where internal methods are hidden and changes are achieved through passing parameters in an API fashion.