directing messages ('intros') at a certain user - ruby-on-rails

Question

Simple rails app: I have 2 models, user and intro [which is simply a message]. Each message has a sender (user) and receiver (user). Here's the intro model (validations omitted):
class Intro < ActiveRecord::Base
attr_accessible :content
belongs_to :sender, class_name: "User"
belongs_to :receiver, class_name: "User"
default_scope order: 'intros.created_at DESC'
end
and now the user model:
class User < ActiveRecord::Base
attr_accessible :name, :email, :password, :password_confirmation
has_secure_password
has_many :sent_intros, foreign_key: "sender_id", dependent: :destroy, class_name: "Intro"
has_many :received_intros, foreign_key: "receiver_id", dependent: :destroy, class_name: "Intro"
before_save { |user| user.email = email.downcase }
before_save :create_remember_token
private
def create_remember_token
self.remember_token = SecureRandom.urlsafe_base64
end
end
The app currently lets the current user submit an intro into a form and associate with that message (a home page shows sent_intros). However, I could use some help in the intros_controller/create method when it comes to the received_intros function. How do I let an intro that is created by the current user be associated with (i.e. sent to) another specific user so that I can route it to a recipient's inbox? Thank you.
class IntrosController < ApplicationController
before_filter :signed_in_user
def create
#sent_intro = current_user.sent_intros.build(params[:intro])
if #sent_intro.save
flash[:success] = "Intro sent!"
redirect_to root_path
else
render 'static_pages/home'
end
end
def index
end
def destroy
end
end

Answer 1

It doesn't look like you're allowing the current_user to assign a receiver to an intro they create? You need to have an input on your form that allows a user to set a valid receiver_id, and you need to add receiver_id to attr_accessible:
class Intro < ActiveRecord::Base
attr_accessible :content, :receiver_id
#Rest of your code
end
With that, when your intro is created, it will be properly associated with both a sender and a receiver. You would then be able to access a current_user's received intros with the method current_user.received_intros
You may want to add some validation to the Intro model to make sure both a receiver and a sender exist.
EDIT: You can add the receiver_id field to your code in the comments like so:
<!-- In your first view -->
<% provide(:title, 'All users') %>
<h1>All users</h1>
<%= will_paginate %>
<ul class="users">
<%= #users.each do |user| %>
<%= render user %>
<%= render 'shared/intro_form', :user => user %> <!-- make sure you pass the user to user intro_form -->
<% end %>
</ul>
<%= will_paginate %>
<!-- shared/intro_form -->
<%= form_for(#sent_intro) do |f| %>
<%= render 'shared/error_messages', object: f.object %>
<div class="field">
<%= f.text_area :content, placeholder: "Shoot them an intro..." %>
</div>
<%= observe_field :intro_content, :frequency => 1, :function => "$('intro_content').value.length" %>
<%= f.hidden_field :receiver_id, :value => user.id %> <!-- Add this to pass the right receiver_id to the controller -->
<%= f.submit "Send intro", class: "btn btn-large btn-primary" %>
<% end %>