Short circuiting partials 5
I tend to think of partials as mini-components. I don't like it when the page using the partial "knows" too much about what's in the partial. For instance, if your partial displays a collection of things but shouldn't display anything if the collection is empty, then you'll usually see something like this:
The outer page has to know which collection of things the partial is going to use and performs some display logic around that. Shouldn't this all be contained in the partial? The outer page should just know that it is going to use a partial and that's it. So our outer page will look like this:
Now it looks like a self-contained component. Good. Of course, we now have to put that outer display logic in the partial.
Now the messy part is the big
Can it be as simple as putting a
Wow! One whole line shorter. It doesn't look like much in this small contrived example, but I think it makes the purpose of the partial clearer and doesn't clutter up the calling page. Give it a shot.
outer page stuff...
<% unless some_object.has_many_things.empty? %>
<h3>My collection of stuff</h3>
<%= render :partial => 'my_partial', :locals => { :collection_of_stuff => some_object.has_many_things } %>
<% end %>
more outer page stuff... outer page stuff...
<%= render :partial => 'my_partial', :locals => { :some_object => some_object } %>
more outer page stuff... <% unless some_object.has_many_things.empty? %>
<h3>My collection of stuff</h3>
<% some_object.has_many_things.each do |o| %>
do some stuff with <%= o %>
<% end %>
<% end %> unless block around the whole partial. I'd like to just short circuit the whole page if there's nothing to display, similar to what I do in normal methods:
def do_something(some_arg)
return nil unless some_arg
do_something_cool_with_some_arg
end return statement in our partial? It turns out, yes, it is that easy.
<% return if some_object.has_many_things.empty? %>
<h3>My collection of stuff</h3>
<% some_object.has_many_things.each do |o| %>
do some stuff with <%= o %>
<% end %> 
That’s the first useful thing I’ve ever gotten from you, Lee.
Maybe I’ll stop skipping over the posts with your name on them.
Actually, having typed that, you just arrived at work, and reminded me what you’re like..
u save 1 line… dude its only an end… how much of a deal is that…
wow,
Cutting out one line and a level of indentation is just a pleasant side-effect. I believe the main benefit is the partial has become more of a stand-alone component by consolidating the view logic.
-Lee