User and Link association difficulties - ruby-on-rails

Question

I have a user and link MVC. I listed them below. Essentially when I create a new link I want it to be tied to my user and then display the users email with the quote on my show page, but I continue to get a nil value for a user when I authenticate even though I have:
a user and link assocation
permitted :user_id in my strong parameters
have a before_filter that requires a user be logged in when making a new request
have a user_id in my link schema
If you take a look at my show.html.erb and the line <%= #link.user.try(:email) %>, this is where the users email should appear that posted the link, but they all come across as nil values.
I am a little lost right now as to why I can't get this to work, any help would be very appreciated!
Models:
class User < ActiveRecord::Base
has_many :links
acts_as_voter
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
end
class Link < ActiveRecord::Base
belongs_to :user
acts_as_votable
attr_accessor :avatar
mount_uploader :avatar, AvatarUploader
end
Controllers:
class LinksController < ApplicationController
before_filter :authenticate_user!, except: [:index, :show]
def index
#links = Link.all
end
def show
#link = Link.find(params[:id])
end
def new
#link = Link.new
end
def edit
end
def create
#link = Link.new(link_params)
if #link.save
redirect_to root_path
else
render 'new'
end
end
private
def link_params
params.require(:link).permit(:title, :url, :avatar, :user_id)
end
end
show.html.erb:
<p id="notice"><%= notice %></p>
<p>
<strong>Author:</strong>
<%= #link.title %>
</p>
<p>
<strong>Quote:</strong>
<%= #link.url %>
</p>
<small class="author">Submitted <%= time_ago_in_words(#link.created_at) %> ago by <%= #link.user.try(:email) %></small>
Schema:
create_table "links", force: :cascade do |t|
t.string "title"
t.string "url"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "user_id"
t.integer "cached_votes_total", default: 0
t.integer "cached_votes_score", default: 0
t.integer "cached_votes_up", default: 0
t.integer "cached_votes_down", default: 0
t.string "avatar"
end
create_table "users", force: :cascade do |t|
t.string "email", default: "", null: false
t.string "encrypted_password", default: "", null: false
t.string "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.integer "sign_in_count", default: 0, null: false
t.datetime "current_sign_in_at"
t.datetime "last_sign_in_at"
t.string "current_sign_in_ip"
t.string "last_sign_in_ip"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end

Answer 1

It doesn't sound like user_id is ever set. As it happens, you probably don't want to set it via the params anyway (since these can be manipulated by the user).
Instead, replace
#link = Link.new(link_params)
With
#link = current_user.links.build(link_params)
If links always have a user, I would also mark the user_id column as not null instead of littering my app with calls to try (And I would in general prefer try! to try)

Answer 2

1.As I understand, the logic is that you can only create links once your logged in. And a user can create links only for him/her (only user logged in can be the owner of links he created). In that case you should not expose user_id in form but instead add it in the create action:
def create
#link = Link.new(link_params)
if #link.save
current_user.links << #link
redirect_to root_path
else
render 'new'
end
end
2.Also, if you don't allow orphan links(with no user as the owner), then I suggest not using user.try(:email) but instead #link.user.email
If you are accessing user object through #link then you could preload it in the show action to save some DB queries
def show
#link = Link.includes(:user).find(params[:id])
end
Make these changes and try again. Also, email is required for a user if you are using default devise configuration, so .try(:email) returning nil might mean that the user object is not found, which means that the associations are not properly set (my version might fix that)