Ruby on Rails

On Dec 13, 2010, at 2:40 PM, Marnen Laibow-Koser wrote:

> Rob Biedenharn wrote in post #968091:
>> On Dec 12, 2010, at 4:59 PM, Rodrigo Mendona wrote:
>>
>>> other way is
>>>
>>> <%=p.user.name unless p.user.empty?%>
>>
>> Or, you can push that into the model and avoid the extra logic in the
>> view:
>>
>> class Post
>> def user_name
>> self.user ? self.user.name : "(none)"
>> end
>> end
>>
>> <% @posts.each do |post| %>
>> <%= post.user_name %>
>> <% end %>
>
> Why would you do that, though? Sure, it keeps a little bit of method
> chaining out of the view, but at the cost of a completely unnecessary
> model method.
>
> If a calculation were being performed to get this value, I'd agree
> with
> defining a method. But I think accessor method chaining in the view
> is
> generally acceptable, particularly when it simply involves traversing
> already loaded associations.

But I will remind you that the OP found that the problems came from
Posts that did not have an associated User. In such cases, post.user
will be nil and nil.empty? does not exist. Perhaps you meant to say
unless post.user.blank?, but if there are many places where a
post.user_name is used, the extra method avoids Law of Demeter
violations. (Or "Suggestion of Demeter" if you prefer.)

-Rob

>
>>
>> You could name the method something like "author_string" or
>> "by_line",
>> too. The idea is to keep the view very clean.
>
> Method chaining is much cleaner than this IMHO.
>
>> You might be able to
>> simply `delegate :name, :to => :user` in your Post model, but that
>> would have given you the same problem if the post.user_id referred to
>> a non-existent User.
>
> delegate seems smelly in this context.
>
>>
>> -Rob
>
> Best,
> --
> Marnen Laibow-Koser
> http://www.marnen.org
> marnen@marnen.org
>
> --
> Posted via http://www.ruby-forum.com/.
>
> --
> You received this message because you are subscribed to the Google
> Groups "Ruby on Rails: Talk" group.
> To post to this group, send email to rubyonrails-
> talk@googlegroups.com.
> To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com
> .
> For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en
> .
>

Rob Biedenharn
Rob@AgileConsultingLLC.com http://AgileConsultingLLC.com/
rab@GaslightSoftware.com http://GaslightSoftware.com/

--
You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.