Undefined local variable / no method error in Ruby on Rails

Question

Can anyone explain to me why I am getting this error? Rails is about conventions. Is there a more conventional way of doing what I'm trying to do below?

undefined local variable or method `hello_world' for #<#<Class:...>:...>

Here are my files:

welcome_controller.rb

class WelcomeController < ApplicationController
  def hello_world
    "Hello, World"
  end
end

welcome/index.html.erb

<%= hello_world %>

routes.rb

Rails.application.routes.draw do
  get 'welcome/index'
  root 'welcome#index'
end

change subject - how to call controller methods inside a view?..suggestion.. — Arup Rakshit
– Arup Rakshit, Commented May 1, 2014 at 20:36
I followed along with the Beginning Guide to Rails and the Code School Rails for Zombies, but I'm still confused. I thought I was doing it right. — TyLeisher
– TyLeisher, Commented May 1, 2014 at 23:40

Arup Rakshit · Accepted Answer · 2014-05-01 21:16:24Z

7

Or do as :

class WelcomeController < ApplicationController
 helper_method :hello_world
 def hello_world
    "Hello, World"
 end
end

Now call it inside the view :

<%= hello_world %>

Read helper_method

Declare a controller method as a helper, to make the hello_world controller method available to the view.

edited May 1, 2014 at 21:16

answered May 1, 2014 at 20:18

Arup Rakshit

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1 Comment

TyLeisher Over a year ago

Just so I'm clear, cause I don't really understand... if I wanted to do a basic hello world without the helper_method, SHOULD I have just created a class, and given hello_world inside the class? Reading up on helper_method now, but not sure why I need it.

Uri Agassi · Accepted Answer · 2014-05-01 20:40:43Z

4

You can use a helper to allow you to write that in your ERB:

module WelcomeHelper

  def hello_world
     "Hello, World"
  end

end

and now, your ERB should work:

<%= hello_world %>

edited May 1, 2014 at 20:40

answered May 1, 2014 at 20:28

Uri Agassi

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2 Comments

Kirti Thorat Over a year ago

@UriAgassi inclusion of WelcomeHelper in Controller would only be required if OP wants to access hello_world in Controller.

Arup Rakshit Over a year ago

@UriAgassi You need to use helper WelcomeHelper inside the controller.. Do that to make the answer complete, so that future readers not need to go and search it inside the doc..

gotva · Accepted Answer · 2014-05-01 21:21:09Z

2

hello_world is action defined in controller and routes You need to define variable(s) in your action. This variable(s) will be accessible in the view

class WelcomeController < ApplicationController

 # this is action
 def index
    # this is variable
    @hello_world = "Hello, World"
 end

end

# view index.html.erb
# this calls variables defined in action
<%= @hello_world %>

Update1:

And if you define your route to welcome#index the action name in controller should be index!

edited May 1, 2014 at 21:21

answered May 1, 2014 at 20:16

gotva

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4 Comments

Kirti Thorat Over a year ago

This will not work unless you set the variable in WelcomeController #index action. As OP wants to access that particular value in index.html.erb. Change you action name to index instead of hello_world

Arup Rakshit Over a year ago

@KirtiThorat instance variables can be used inside a view..why should it to be moved inside #index ?

Kirti Thorat Over a year ago

Because OP is rendering index.html.erb and NOT hello_world.html.erb

Kirti Thorat Over a year ago

@ArupRakshit Try it in any of your Rails application and let me know if it works for you.

Richard Peck · Accepted Answer · 2014-05-02 10:15:03Z

0

This is more Rails-convention for you:

#config/routes.rb
root to: "welcome#index"
resources :welcome

#app/controllers/welcome_controller.rb
Class WelcomeController < ApplicationController
    def index
       #-> will render #app/views/welcome/index.html.erb
    end
end

#app/views/welcome/index.html.erb
Hello World
<%= hello_world %> <!-- Use `@Arup`'s answer to create a helper method -->

answered May 2, 2014 at 10:15

Richard Peck

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Comments

raman rayat · Accepted Answer · 2017-03-04 07:07:17Z

0

You can use print 'ff'. it simply work for me :)

answered Mar 4, 2017 at 7:07

raman rayat

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