I have a comment model, what to use in my views? @comment, :comment or comment?

Question

I have a comment model, I've seen examples of using @comment, :comment, comment to reference the object in MVC. how do I know which is which? Is there a distinction?

Answer 1

It really depends on the context.

The first one, @comment is usually used (as John Topley similarly explained) for setting up a variable to be passed down the request chain to your views, helpers and partials that are rendered from that action.

If you're using it in a form_for you would reference the @comment object you most likely set up in the controller:

<% form_for @comment do |f| %>

If you're passing a comment object as a local to a partial you could specify it as a symbol (as John Topley said):

<%= render :partial => "info", :locals => { :comment => @comment }

And if you were using it as a local variable you may be rendering a collection of comments:

<%= render :partial => @post.comments %>

Passing the comments collection to partial will introspect upon the first object in here and determine it is of the Comment class and therefore will try to render the comments/_comment.html.erb partial for each of the items in the collection (regardless of what type the others are, this is a gotcha), making them each available as comment inside it.