New to Ruby on Rails - Association Issue - ruby-on-rails-4

Question

I am trying to set the associations . By now I have both models Post and Comment with their associations (in theory).
The problem is that when I try to see the comment of a specific post it says that such method does not exist.
I am sure forgetting something kinda obvious but I can't figure it out.
Thanks in advance!
MODELS
class Post < ActiveRecord::Base
has_many :comments, dependent: :destroy
end
class Comment < ActiveRecord::Base
belongs_to :post
end
And i got the error on rails console:
p = Post.all
p[0].comments
"undefined method comments for post"
Controllers:
Coment:
class CommentsController < ApplicationController
before_action :set_comment, only: [:show, :edit, :update, :destroy]
# GET /comments
# GET /comments.json
def index
#comments = Comment.all
end
# GET /comments/1
# GET /comments/1.json
def show
end
# GET /comments/new
def new
#comment = Comment.new
end
# GET /comments/1/edit
def edit
end
# POST /comments
# POST /comments.json
def create
#comment = Comment.new(comment_params)
respond_to do |format|
if #comment.save
format.html { redirect_to #comment, notice: 'Comment was successfully created.' }
format.json { render action: 'show', status: :created, location: #comment }
else
format.html { render action: 'new' }
format.json { render json: #comment.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /comments/1
# PATCH/PUT /comments/1.json
def update
respond_to do |format|
if #comment.update(comment_params)
format.html { redirect_to #comment, notice: 'Comment was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #comment.errors, status: :unprocessable_entity }
end
end
end
# DELETE /comments/1
# DELETE /comments/1.json
def destroy
#comment.destroy
respond_to do |format|
format.html { redirect_to comments_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_comment
#comment = Comment.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def comment_params
params.require(:comment).permit(:post_id, :body)
end
end
Post:
class PostsController < ApplicationController
before_action :set_post, only: [:show, :edit, :update, :destroy]
# GET /posts
# GET /posts.json
def index
#posts = Post.all
end
# GET /posts/1
# GET /posts/1.json
def show
end
# GET /posts/new
def new
#post = Post.new
end
# GET /posts/1/edit
def edit
end
# POST /posts
# POST /posts.json
def create
#post = Post.new(post_params)
respond_to do |format|
if #post.save
format.html { redirect_to #post, notice: 'Post was successfully created.' }
format.json { render action: 'show', status: :created, location: #post }
else
format.html { render action: 'new' }
format.json { render json: #post.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /posts/1
# PATCH/PUT /posts/1.json
def update
respond_to do |format|
if #post.update(post_params)
format.html { redirect_to #post, notice: 'Post was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #post.errors, status: :unprocessable_entity }
end
end
end
# DELETE /posts/1
# DELETE /posts/1.json
def destroy
#post.destroy
respond_to do |format|
format.html { redirect_to posts_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_post
#post = Post.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def post_params
params.require(:post).permit(:title, :body)
end
end

Answer 1

Try this
has_many :comments, :class_name => "Comment", :foreign_key => :post_id

Answer 2

I think this is because you're trying to pull all comments for all posts, try this in rails console. This will only pull the first Post and then its related comment.
p = Post.first
p.comments
Are you getting an error on the view as well? If so, can you post the code from the view in question.