Rails undefined method - ruby-on-rails

Question

Why is this undefined? Does it have something to do with the #current_user?
I'm trying to create tasks for my challenges. And the created task should get /achievements. However, I get a GET 500 error.
This is the error I get:
NoMethodError at /achievements
==============================
> undefined method `achievements' for #<User:0x00000105140dd8>
app/controllers/achievements_controller.rb, line 5
--------------------------------------------------
``` ruby
1 class AchievementsController < ApplicationController
2
3
4 def index
> 5 #achievements = #current_user.achievements
6 render :json => #achievements
7 end
8
9 def new 10 #achievement = Achievement.new
This is my code in my controller
class AchievementsController < ApplicationController
def index
#achievements = #current_user.achievements
render :json => #achievements
end
def new
#achievement = Achievement.new
render :json => #achievement
end
#create a new achievment and add it to the current user
#check then set the acheivments pub challenge id to the current pub challenge
def create
#achievement = Achievement.new achievement_params
#achievement.user = #current_user.id
#achievement.pub_challenge = params[:id]
if #achievement.save
# render :json => #achievement #{ status: 'ok'}
else
render :json => {:errors => #achievement.errors}
end
end
def show
#achievement = Achievement.find params[:id]
render :json => #achievement
end
def destroy
#achievement = Achievement.find params[:id]
#achievement.destroy
end
private
def achievement_params
params.require(:achievement).permit(:pub_challenges)
end
end

Answer 1

You are missing the has_many :achievements relation in your User model.

Answer 2

You'll need to create the ActiveRecord associations you require:
#app/models/user.rb
class User < ActiveRecord::Base
has_many :achievements
end
#app/models/achievement.rb
class Achievement < ActiveRecord::Base
belongs_to :user
end
This will give you the ability to call the achievements method on any User objects you have.
Error
The error you have is described as such:
undefined method `achievements' for #<User:0x00000105140dd8>
This basically means that you're trying to call an undefined method on a User object. Might sound simple, but really, most people don't understand it.
To explain properly, you have to remember that Rails, by virtue of being built on Ruby is object orientated. This means that everything you do in Rails should be structured around objects - which are defined in your Models:
This means that each time you call an object, you're actually above to invoke a series of "methods" which will give you the ability to either manipulate the object itself, or any of the associated functionality it has.
The problem you have is that your User object doesn't have the achievements method. Whilst you could simply do the following to fix the issue, because it's Rails, you'll need to populate the record with associative data:
#app/models/user.rb
class User < ActiveRecord::Base
has_many :achievements #-> what you need
def achievements
#this will also fix the error you see, although it's fundamentally incorrect
end
end

Answer 3

Something that helped me with this type of error was that the database table was missing the relevant column. Adding the required column to the database fixed the issue.