The transform property gives us a way to position and alter elements. It comes in two settings: 2-Dimensional and 3-Dimensional. Each of those comes with different settings and properties, we’ll take a look at both of them in this tutorial.

Syntax-wise, transform property has multiple sub-properties which declare how the element should be transformed. For instance, in the example above, we used the scale property. But there are a number of these like rotate, translate and skew in addition to scale. Let's look at 2D transforms first.

2D Transforms

2D transforms work on x-axis and y-axis, while 3D transforms work on x-axis, y-axis, and z-axis.

Let's look at the four 2D Transform properties:

2D rotate

A preprocessor is a tool that transforms one type of code into another type. In this tutorial, we will look into two popular preprocessors: one for HTML (called Haml) and the other one for CSS (called Sass). Haml and Sass are much more easier to write, and provide a few very useful features out-of-the-box which are not available in HTML or CSS. Thus, by writing in Haml or Sass, and then using a preprocessor to convert your code into HTML or CSS respectively, you can simplify your development process quite a lot.

Haml

Haml stands for HTML abstract markup language. It aims to provide a good structure and makes your HTML code DRY (Don't Repeat Yourself), logical, and easier to read. We will see an example below to see how it does this.

Installation

It's time to add a second model to the application. The second model will handle comments on articles.

Generating a Model

We're going to see the same generator that we used before when creating the Article model. This time we'll create a Comment model to hold reference to an article. Run this command in your terminal:

$ bin/rails generate model Comment commenter:string body:text article:references

This command will generate four files:

Another important feature of a blog is being able to delete spam comments. To do this, we need to implement a link of some sort in the view and a destroy action in the CommentsController.

So first, let's add the delete link in the app/views/comments/_comment.html.erb partial:

<p>  <strong>Commenter:</strong>
  <%= comment.commenter %>
</p>
<p>
  <strong>Comment:</strong>
  <%= comment.body %></p>
<p>
  <%= link_to 'Destroy Comment', [comment.article, comment],
               method: :delete,
               data: { confirm: 'Are you sure?' } %>
</p>

Clicking this new "Destroy Comment" link will fire off a DELETE /articles/:article_id/comments/:idto ourCommentsController...