Unable to insert data in table using form to submit data - ruby-on-rails

Question

I am unable to insert data in user_preferences table where as I am getting all the attributes in params. I tried inserting value from console by following way since association between User has_one user_preference and UserPreference belongs_to User:
user = User.find(1)
user.user_preferences.title = "MyTitle"
I am getting undefined method "title"
user_preference.rb
class UserPreference < ActiveRecord::Base
belongs_to :user
def self.bgcolor_options
[["Orange", "#FF3300"], ["Green", "#00FF00"], ["Blue", "#0000FF"], ["Pink", "#FF0066"], ["Yellow", "#FFFF00"], ["White", "#FFFFFF"]]
end
def self.font_options
[["Times New Roman", "Times New Roman"], ["Verdana", "Verdana"],["Arial", "Arial"],["sans-serif", "sans-serif"]]
end
end
user_preferences_controller.rb
class UserPreferencesController < ApplicationController
def new
#user_preference = UserPreference.new
end
def create
#user_preference = UserPreference.new(user_pref_params)
#user_preference.save unless user_signed_in?
render 'user_preferences/new'
end
def edit
end
def update
end
private
def user_pref_params
params.require(:user_preference).permit(:title, :bgcolor, :font, :description)
end
end
routes.rb
Rails.application.routes.draw do
resources :user_preferences
post "/user_preferences/new"
devise_for :users
devise_scope :user do
authenticated :user do
root :to => 'user_preferences#new', as: :authenticated_root
end
unauthenticated :user do
root :to => 'devise/registrations#new', as: :unauthenticated_root
end
end
user_preferences/new.html.erb
<%= form_for #user_preference, :url => { :action => "create" } do |u|%>
<div style="background-color:#{current_user.user_preference.bgcolor.nil? ? '#FFFFFF' : current_user.user_preference.bgcolor}">
<p>
<%= u.label :title %><br>
<%= u.text_field :title %>
</p>
<p>
<%= u.label :description %><br>
<%= u.text_field :description %>
</p>
<p> <%= u.label :back_ground_color %><br>
<%= u.select :bgcolor, options_for_select(UserPreference.bgcolor_options) %>
</p>
<p>
<%= u.label :font %><br>
<%= u.select :font, options_for_select(UserPreference.font_options) %>
</p>
<br >
<p>
<%= u.submit %>
</p>
<hr >
<div style="background: #{current_user.user_preferences.bgcolor};"></div>
<div style="background-color:#{current_user.user_preferences.font.nil? ? 'Arial' : current_user.font}">
This is the changes made in background
</div>
</div>
<% end %>
schema.rb
ActiveRecord::Schema.define(version: 20150422034042) do
create_table "user_preferences", force: :cascade do |t|
t.text "title"
t.string "font"
t.text "description"
t.string "bgcolor"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "user_id"
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"
t.datetime "updated_at"
end
add_index "users", ["email"], name: "index_users_on_email", unique: true
add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
end
Adding User.rb code
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
has_one :user_preference
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
end

Answer 1

You're accessing the wrong association on user:
user.user_preferences.title = "MyTitle"
user_preferences is a has_many association, and returns multiple objects. The error itself also mentions this (something like ActiveRecord_Associations_CollectionProxy).
Simply access the has_one association and it will work:
user.user_preference.title = "MyTitle"

Answer 2

for the console part its not a javascript if you want to set to relation you have to use a variabel to assign, and not to use user_preference(s) note the s and its has_one relation and it should be user_preference and in your User Model it should be
# User Model
has_one :user_preference
# Console
user = User.first
preferences = user.user_preference
preferences.title = "MyTitle"
preferences.save
user.reload.preferences.title # should be "MyTitle"