Adding a comment model to associate with a post/user model - ruby-on-rails

Question

I finally was able to associate a user model with a post model with:
def create
#post = Post.new(post_params)
#post.user = current_user
Right now I'm trying to create a comment in the Post#Show page but continue to receive an error regarding my form. The two errors I'm running into are:
NoMethodError in Posts#show undefined method `comments_path'
when I have #comment = Comment.new in Post#show. When it's removed I get:
ArgumentError in Posts#show First argument in form cannot contain nil or be empty
What could possibly be wrong with my form? Also if someone can recommend a better way to associate my 3 models (basically have a user_id and a post_id when comment is created I'm open for suggestions). My comment form is going to appear within the Post#Show page. My current code is:
Comment Model
belongs_to :user
belongs_to :post
User Model
has_many :posts
has_many :comments
Post Model
has_many :comments
belongs_to :user
Comment Controller
class CommentsController < ApplicationController
before_action :find_comment, only: [:show, :edit, :update, :destroy]
def index
#comments = Comment.all
end
def new
#comment = Comment.new
end
def create
#post = Post.find(params[:id])
#comment = #post.comments.build(comment_params)
#comment.user = current_user
if #comment.save
flash[:notice] = "Successfully created..."
redirect_to comments_path
else
flash[:alert] = "failed"
redirect_to root_path
end
end
def show
end
def edit
end
def update
if #comment.update
flash[:notice] = "You updated your comment"
else
flash[:alert] = "Failed to update"
end
def destroy
#comment.destroy
redirect_to '/'
end
private
def find_comment
#comment = Comment.find(params[:id])
end
def comment_params
params.require(:comment).permit(:comment)
end
end
Post Controller
class PostsController < ApplicationController
before_action :find_post, only: [:show, :edit, :update, :destroy]
def index
#posts = Post.all
end
def new
#post = Post.new
end
def create
#post = Post.new(post_params)
#post.user = current_user
if #post.save!
flash[:notice] = "Successfully created..."
redirect_to posts_path
else
flash[:danger] = "failed to add a post"
render 'new'
end
end
def show
end
def edit
end
def update
if #post.update
flash[:notice] = "Successfully updated"
redirect_to post_path
else
flash[:alert] = "Failed to update Post"
redirect_to :back
end
end
def destroy
if #post.destroy
flash[:notice] = "Successfully delete"
redirect_to posts_path
else
flash[:danger] = "Wasn't able to delete Blog post."
redirect_to :back
end
end
private
def find_post
#post = Post.find(params[:id])
end
def post_params
params.require(:post).permit(:title, :body, :description)
end
end
Post#Show View
<%= render '/comments/form' %>
Comment#form
<%= form_for #comment do |f| %>
<%= f.label :comment, "Title" %>
<%= f.text_field :comment, placeholder: "Write a comment" %>
<%= f.submit "Submit" %>
<% end %>
If there is something missing please ask me to update my post. Thank you all who help me better understand my problem.

Answer 1

Your associations seem fine. The error
NoMethodError in Posts#show undefined method `comments_path'
means that you don't have the route comments_path or Comments#Create. Basically, when you have a form_for with a Comment as the parameter, it assumes you are wanting to go to the create or update route, depending if it's a new record. The easiest thing to do would be to add
resources :comments
to your routes file. However, since you want a comment associated with a post, you want to modify your routes file to have:
resources :posts do
resources :comments
end
Then, change your form to look like this:
<%= form_for [#post, #comment] do |f| %>
So when you submit a form, you will have a params[:post_id] and a params[:id] to play with. Find the Post with the params[:post_id]. Ignore the params[:id] when you're creating a comment, but use it when you're updating a comment.
Edit: Here is a link to some help regarding Nested Resourcing.