undefined local variable or method `post'

Question

Here is my form for my comments _form.html.erb:

<%= form_for([post, @comment]) do |f| %>
    <p>
        <%= f.text_area :body, placeholder: "Write a comment!" %>
    </p>
    <br>
    <p> <%= f.submit %> </p>

<% end %>

and here is my posts form _form.html.erb:

<%= form_for @post, url: post_path(@post), method: :patch do |f| %>
        <% if @post.errors.any? %>
          <div id="errors">
            <h2><%= pluralize(@post.errors.count, "Error") %> Prevent this post from posting</h2>
            <ul>
                <% @post.errors.full_messages.each do |msg| %>
                    <li><%= msg %></li>

                <% end %>
            </ul>
          </div>
        <% end %>
        <p>
             <%= f.label :Edit_Post %><br>
             <%= f.text_area :body %>
        </p>
        <p>
            <%= f.submit  %>
        </p>

<% end %>

Here is my comments_controller.rb:

class CommentsController < ApplicationController
    def create 
       @post = Post.find(params[:post_id])
       @comment = @post.comments.build(params[:comment])
       @comment.save
       redirect_to @posts
    end
    def destroy
        @user = User.find(session[:user_id])
        @posts = Post.find(params[:post_id])
        @comment = @post.comments.find(params[:id])
        @comment.destroy
        redirect_to post_path(@post)
    end
end

And here is my posts_controller.rb:

class PostsController < ApplicationController
    before_action :load_post, only: [:show, :edit, :update, :destroy]

    def index
        @user = User.find(session[:user_id])
        @posts = Post.all
    end
    def welcome
        @user = User.find(session[:user_id])
        @posts = Post.order("created_at desc").limit(4).offset(1)
        @signed_in_user = session[:user_id]
    end
    def posts
        @user = User.find(session[:user_id]) unless session[:user_id] == nil
        redirect_to login_path, notice: "You're not logged in" unless @user 
        @signed_in_user = session[:user_id]

    end
    def new 
        @post = Post.new
        @user = User.find(session[:user_id])
    end
    def create 
        @user = User.find(session[:user_id])        
        @post = Post.new(post_params)

        @post.user_id = @signed_in_user

        if  @post.save 
            redirect_to dashboard_path 
        else
            render 'new'
        end
    end
    def show
        @user = User.find(session[:user_id])

        @signed_in_user = session[:user_id]
    end
    def edit
        @user = User.find(session[:user_id])
    end 

    def update
        if @post.update(post_params)
            redirect_to @post, notice: "Your post has been updated!"
        end
    end
    def destroy
        @user = User.find(session[:user_id])
        @post.user_id = @signed_in_user

        @post.destroy

        redirect_to posts_path
    end

    private

    def load_post
        @post = Post.find(params[:id])
    end
    def post_params
        params.require(:post).permit(:body)
    end
end

Having this issue. Any help will be appreciated. Here is the picture of the error I am having:

EDIT: Here is my log

Started GET "/posts/24" for 127.0.0.1 at 2015-09-28 18:46:44 -0700
Processing by PostsController#show as HTML
  Parameters: {"id"=>"24"}
  [1m[36mPost Load (0.0ms)[0m  [1mSELECT  "posts".* FROM "posts" WHERE "posts"."id" = ? LIMIT 1[0m  [["id", 24]]
  [1m[35mUser Load (0.0ms)[0m  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 1]]
  [1m[36mCACHE (0.0ms)[0m  [1mSELECT  "posts".* FROM "posts" WHERE "posts"."id" = ? LIMIT 1[0m  [["id", "24"]]
  [1m[35m (0.0ms)[0m  SELECT COUNT(*) FROM "comments" WHERE "comments"."post_id" = ?  [["post_id", 24]]
  Rendered comments/_form.html.erb (1.0ms)
  Rendered posts/show.html.erb within layouts/application (7.0ms)
  Rendered layouts/_nav.html.erb (1.0ms)
Completed 200 OK in 451ms (Views: 412.0ms | ActiveRecord: 1.0ms)

Answer 1

undefined local variable or method `post'

Your error message says it all. It tells you that, you don't have post defined in the corresponding controller action for your view. That's why you are getting that error.

So, you need to define @post (usually you use a instance variable in such cases) in the corresponding controller action i.e. PostsController's show action. You actually need to define @comment as well as you don't have it in your controller action currently. So, update your show method like this:

def show
    @user = User.find(session[:user_id])
    @signed_in_user = session[:user_id]

    # you need to define @post and @comment
    @post = Post.find params[:id]
    @comment = Comment.new(post: @post)
end

Then, you can use @post and @comment in your view, so your comments/_form.html.erb would look like this:

<%= form_for([@post, @comment]) do |f| %>
. . . 
. . .