unknown attribute 'category_id' for Post - ruby-on-rails

Question

I am trying to create categories for my posts. To do so, I generated a new category model. Although I have associated the two models, I am still receiving this error:
ActiveRecord::UnknownAttributeError: unknown attribute 'category_id' for Post.
I have doublechecked the schema which does include category_id for the post table:
add_index "comments", ["post_id"], name: "index_comments_on_post_id"
create_table "posts", force: :cascade do |t|
t.string "title"
t.text "description"
t.string "cost"
t.integer "openspots"
t.boolean "approval"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "user_id"
t.integer "category_id"
end
add_index "posts", ["user_id"], name: "index_posts_on_user_id"
Here are my associations as well:
class Category < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
belongs_to :category
has_many :comments
default_scope { order('created_at DESC') }
end
Finally I wanted to include my posts controller:
class PostsController < ApplicationController
def new
# #post = Post.new
#post = Post.new
#categories = Category.all.map{|c| [ c.name, c.id ] }
end
def create
#post = Post.new(params.require(:post).permit(:title, :description, :cost, :openspots, :approval, :category_id))
#post.category_id = params[:category_id]
#post.user = current_user
if #post.save
flash[:notice] = "Post was saved."
redirect_to #post
else
flash[:error] = "There was an error saving the post. Please try again."
render :new
end
end
def update
#post = Post.find(params[:id])
#post.category_id = params[:category_id]
if #post.update_attributes(params.require(:post).permit(:title, :description))
flash[:notice] = "Post was updated."
redirect_to #post
else
flash[:error] = "There was an error saving the post. Please try again."
render :edit
end
end
def edit
#post = Post.find(params[:id])
#post.category_id = params[:category_id]
end
def destroy
end
def index
#posts = Post.all
end
def show
#post = Post.find(params[:id])
end
end
Whenever I create a new post, the post is created successfully;however, the category id is never saved.
Here is my view as well:
<h1>New Post</h1>
<div class="row">
<div class="col-md-4">
<p>Guidelines for posts</p>
<ul>
<li>Make sure it rhymes.</li>
<li>Don't use the letter "A".</li>
<li>The incessant use of hashtags will get you banned.</li>
</ul>
</div>
<div class="col-md-8">
<%= form_for #post do |f| %>
<div class="form-group">
<%= f.label :title %>
<%= f.text_field :title, class: 'form-control', placeholder: "Enter post title" %>
</div>
<div class="form-group">
<%= f.label :description %>
<%= f.text_area :description, rows: 8, class: 'form-control', placeholder: "Enter post description" %>
</div>
<div class="form-group">
<%= f.label :cost %>
<%= f.number_field :cost, rows: 8, class: 'form-control', placeholder: "Enter cost" %>
</div>
<div class="form-group">
<%= f.label :openspots %>
<%= f.number_field :openspots, rows: 8, class: 'form-control', placeholder: "Enter Number of Open Spots" %>
</div>
<div class="form-group">
<%= f.label :approval %>
<%= f.check_box :approval, rows: 8, class: 'form-control', placeholder: "Check if Approval Necessary" %>
</div>
<div class="form-group">
<%= f.label :category %>
<%= f.collection_select :category_id, Category.order(:name),:id,:name, include_blank: true %>
</div>
<div class="form-group">
<%= f.submit "Save", class: 'btn btn-success' %>
</div>
<% end %>
</div>
</div>