sending specific data into a collection partial - ruby-on-rails-3

Question

I have a User class with a has_many :messages and a Message class which belongs_to :user. In the Message controller's show action has the corresponding view:
<% if #messages.any? %>
<ol class="microposts">
<%= render partial: 'shared/message', collection: #messages %>
</ol>
<% end %>
And the shared/_message.html.erb template looks like this:
<li id="<%= message.id %>">
<span class="content"><%= message.body %></span>
<% user_id = message.from %>
<% user = User.find(user_id) %>
From: <%= user.name %>
</li>
I feel like the following two lines should be done in the Messages controller from what I read in tutorials on Rails:
<% user_id = message.from %>
<% user = User.find(user_id) %>
But how would I pass each message's corresponding from value (which stores user.id) into the partial?
thanks,
mike

Answer 1

So far i have understood that you have a from column in your messages table which stores the user_id. So if you call message.from it returns the user_id. Then you can do the following
class Message < AR::Base
belongs_to :user, :foreign_key=>'from'
end
In your controller
#messages = Message.all.includes(:user)
#It will load messages and will associated users eager loaded.
Now in your view you can call message.user.name to get the user's name directly. You dont need these following two lines in your view at all
<% user_id = message.from %>
<% user = User.find(user_id) %>
Let me know if ive missed anything.
UPDATE:
Here is what Ive tried with
User Model
class User < ActiveRecord::Base
attr_accessible :age, :name
has_many :sent_messages, :class_name=>'Message', :foreign_key => 'from'
has_many :received_messages,:class_name=>'Message', :foreign_key => 'user_id'
end
#Contains Data:
#<User id: 1, name: "p1", age: 27, ... ...>,
#<User id: 2, name: "p2", age: 25, ... ...
Message Model
class Message < ActiveRecord::Base
attr_accessible :body, :sender, :title, :receipent
belongs_to :sender, :class_name => 'User', :foreign_key => 'from'
belongs_to :receipent, :class_name => 'User', :foreign_key => 'user_id'
end
Now say p1 is sending a message to p2
p1.sent_messages.create(title: "test title", body: "test body", receipent: p2)
#Result:
#<Message id: 1, title: "test title", body: "test body", user_id: 2, from: 1 ... ... >
Now for a message, you can get both sender and receipent directly like
#messages = Message.includes(:sender, :receipent) # You can load only sender or only receipent
#In View
message.sender.name
#OR
message.receipent.name