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Rails: Refactoring, views, helpers: how does it all go together?

Answer 1

+4 A:

The first thing I'd do would be this:

#index.html.erb
<%= render @beasts %>

#_beast.html.erb
<%= beast.body %>
<%= link_to_next_beast_action(beast) %>    

#beast_helper.rb
def link_to_next_beast_action(beast)
  if beast.dead?
    link_to "bury", bury_beast_path( :id => beast.id ) 
  else
    link_to "kill!", kill_beast_path( :id => beast.id )
  end
end

What I've done is separate out the rendering of the beast into a partial which uses collection semantics.

Then I've moved the logic for showing the kill/bury links into a beast helper. This way if you decide to add another action (for example, 'bring back from dead'), you'll only have to change your helper.

Does this help?

jonnii 2010-02-03 20:36:59

You can even do `render @beasts` as it will realize it's a collection.

Garrett 2010-02-03 21:05:47

Seems like you've arrived at the same refactoring I did. Didn't notice the new answer while I was composing mine.

EmFi 2010-02-03 21:18:05

@EmFi I voted up your answer because you went in to more detail about when to use partials/helpers.

jonnii 2010-02-03 21:30:15

I appreciate it, but it wasn't necessary. I've past the point where I answer questions for the reputation.

EmFi 2010-02-03 21:33:17

Even so, you still deserve the recognition =)

jonnii 2010-02-03 21:39:39

Answer 2

+3 A:

Refactoring makes your views easier to maintain. The problem is choosing where the refactored code goes.

Your two choices are partials and helpers. There's no stone-set rules dictating which should be used where. There are a couple of guidelines floating around like the one stating that helpers should not contain HTML.

Generally partials are better suited for refactoring sections that are more HTML/ERB/HAML than ruby. Helpers on the other hand are used for chunks of ruby code with minimal HTML or generating simple HTML from parameters.

However, I don't agree with the sentiment that helpers should contain no HTML at all. A little is ok, just don't over do it. The way helpers are processed hinder their use for producing large amounts of HTML. Which is why it's suggested that your helpers contain minimal amounts of HTML. If you look at the source the helpers that ship with rails you will notice that most of them generate html. The few that don't, are mainly used to generate parameters and evaluate common conditions.

For example, any of the form helpers or link_to variants fit the first form of helpers. While things like url_for and logged_in? as supplied by various authentication models are of the second kind.

This is the decision chain I use to determine whether to factor code from a view into a partial or helper.

Repeating or nearly identical statements producing a single shallow html tag? => helper.
Common expression used as an argument for another helper? => helper.
Long expression (more than 4 terms) used as an argument for another helper? => helper.
4 or more lines of ruby (that is not evaluated into HTML)? => helper.
Pretty much everything else => partial.

I'm going to use the code you're looking to refactor as an example:

I would refactor the view in the question this way:

app/helpers/beast_helper.rb:

def beast_action(beast)
  if beast.dead?
    link_to "bury", bury_beast_path(beast)
  else
    link_to "kill!", kill_beast_path(beast)
  end
end

app/views/beasts/_beast.html.erb:

<%= beast.body %>
<%= beast_action(beast) %>

app/views/beasts/index.html.erb:

<%= render :partial => "beast", :collection => @beasts %>

It's technically more complicated, because it's 3 files, and 10 lines total as opposed to 1 file and 10 lines. The views are now only 3 lines combined spread over 2 files. The end result is your code is much more DRY. Allowing you to reuse parts or all of it in other controllers/actions/views with minimal added complexity.

As for your body tag id. You should really be using content_for/yield. For that kind of thing.

app/views/layouts/application.html.erb

...
<body id="<%= yield(:body_id) %>">
...

app/views/beasts/index.html.erb

<% content_for :body_id, controller_action %>
...

This will allow you to override the id of the body in any view that requires it. Eg:

app/views/users/preferences.html.erb

<% content_for :body_id, "my_preferences" %>

EmFi 2010-02-03 20:54:58

As long as the partial is at `beasts/_beast.html.erb` you can just do `render @beasts`.

Garrett 2010-02-03 21:06:30

@Garrett: That only works in Rails 2.3 or newer. I have no idea why an new user would be using an older version. But I felt that version was safer.

EmFi 2010-02-03 21:16:44

Good point, with Rails 3 coming soon I think it's safe to start pushing `render @beasts`

Garrett 2010-02-03 21:59:07

Thanks! Your answer was very elucidative; I'll be coming back to check your suggested decision chain frequently until it sinks in. I still have to try out your code, but I imagine it will work. It certainly looks much better. Thanks again.

Baby Diego 2010-02-04 12:57:57

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Rails: Refactoring, views, helpers: how does it all go together?

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