ActiveModel::MissingAttributeError (can't write unknown attribute `user_id`) - ruby-on-rails

Question

I have problems with my comments when my app is deployed. Locally everything is working. The logs from heroku says:
ActiveModel::MissingAttributeError (can't write unknown attribute `user_id`):
2018-01-02T15:52:43.461794+00:00 app[web.1]: [79cd7190-e2d9-4dd0-bf71-
709552e5c6e5] app/controllers/comments_controller.rb:15:in `create'
I have no ideas what is occuring the error. Maybe some database thing?
My CommentsController
class CommentsController < ApplicationController
def create
#post =Post.find(params[:post_id])
#comment =#post.comments.create(params[:comment].permit(:name, :body).merge(user: current_user))
redirect_to post_path(#post)
end
def destroy
#post = Post.find(params[:post_id])
#comment= #post.comments.find(params[:id])
if current_user.id == #comment.user_id
#comment.destroy
end
redirect_to post_path(#post)
end
end
My Models
class User < ApplicationRecord
has_many :posts
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
end
class Post < ApplicationRecord
belongs_to :user, optional: true
has_many :comments, dependent: :destroy
validates :title, presence: true, length: {minimum: 5}
validates :body, presence: true
end
class Comment < ApplicationRecord
belongs_to :post
belongs_to :user
end
My migration-file
class CreateComments < ActiveRecord::Migration[5.1]
def change
create_table :comments do |t|
t.string :name
t.text :body
t.references :post, index: true
t.timestamps
end
end
end
if you need more code or have any ideas please let me know
EDIT: if i add a user_id column i get a SQLite3::SQLException: duplicate column name: user_id: ALTER TABLE "comments" ADD "user_id" integer error
My schema.rb
`create_table "comments", force: :cascade do |t|
t.string "name"
t.text "body"
t.integer "post_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "user_id"
t.index ["post_id"], name: "index_comments_on_post_id"
end
create_table "posts", force: :cascade do |t|
t.string "title"
t.text "body"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "image_file_name"
t.string "image_content_type"
t.integer "image_file_size"
t.datetime "image_updated_at"
t.string "theme"
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", null: false
t.datetime "updated_at", null: false
t.index ["email"], name: "index_users_on_email", unique: true
t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
end

Answer 1

You'll need to add a user_id column to your comments table. The belongs_to requires this. You're also going to need a post_id column, and user_id for your posts table to.
You can customise the column name, but the convention is to use the format parent_table_id.
Here's the key quote, from the docs:
Associations are implemented using macro-style calls, so that you can
declaratively add features to your models. For example, by declaring
that one model belongs_to another, you instruct Rails to maintain
Primary Key-Foreign Key information between instances of the two
models, and you also get a number of utility methods added to your
model.
This means, for example, if your first user has an id of 1, all of their comments and posts will have a user_id value of 1, which does the actual tying together of the records.
Here's an example migration with the relevant line included:
def change
create_table :comments do |t|
...
t.belongs_to :user, index: true
...
end
end
Does that make sense? Let me know if you've any questions and I can update as needed :)

Answer 2

You need to add user_id
Create the migration with
rails g migration AddUserIdToComment user:references
Then do
rake db:migrate
And you should be fine.

Answer 3

Your migration have missing
t.references :user, index: true
So you need to add user_id column within comments table
Update : It seems like you have some migration problem. I suggest you to check for rake db:migrate:status comment and look for any down migration. Once all are up then just run rake db:migrate:down VERSION='VERSION_NUMBER_HERE' and add your user t.references :user, index: true to the same migration and migrate.
PS: Change existing migration if and only if you have not pushed it.