undefined method error using an if conditional statement

Question

I have a helper that checks if a user is signed in or not:

def signed_in?
  !current_user.nil?
end

I also have a helper that allows views and controllers to access the user object by checking the session:

def current_user
  @current_user ||= User.find_by_session(session[:user_id])
end

In one of my controllers, it works fine to pull up the user object

  def index
    @households = current_user.households.all
    @household = current_user.households.build

    respond_to do |format|
      format.html
      format.xml { render xml: @households }
    end
  end

The other controller, however, chokes on the current_user helper when it tries to call the households relation:

def home
  @households = current_user.households.all
  @household = current_user.households.build

  respond_to do |format|
    format.html
    format.xml { render xml: @households }
  end
end

The error:

undefined method `households' for nil:NilClass

I'm pretty stumped and could not find any posts related to this specific subject. I'm new to rails though. Am I asking this question in the wrong way?

Thanks in advance.

Is the helper in application_helpers.rb or users_helpers.rb? I take it you've done the necessary belongs_to and has_many associations? — xiy
– xiy, Commented Sep 17, 2012 at 22:18
the helper is in sessions_helper.rb. I have a belongs_to association on the households and a has_many association on the user. — kypalmer
– kypalmer, Commented Sep 17, 2012 at 22:33

megas · Accepted Answer · 2012-09-17 22:14:33Z

1

Try to include module into your second controller.

For example, helper module looks like this:

module UserHelper
  def current_user
    @current_user ||= User.find_by_session(session[:user_id])
  end
end

Then include it into your controller:

class YourController < ApplicationController
  include UserHelper

  def home
    @households = current_user.households.all
    @household = current_user.households.build

    respond_to do |format|
      format.html
      format.xml { render xml: @households }
    end
  end
end

edited Sep 17, 2012 at 22:14

answered Sep 17, 2012 at 22:05

megas

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3 Comments

kypalmer Over a year ago

I think that this was right on, but now I am getting an error 'Couldn\'t find User without an ID'

megas Over a year ago

@kypalmer, look at the rails tutorial's implementation github.com/railstutorial/sample_app, I think it will be very helpful for your task

kypalmer Over a year ago

This is perfect! I needed to include a call to signed_in? in my controller and include the helpers in my application_controller.rb

Luke Mueller · Accepted Answer · 2012-09-17 22:22:51Z

1

The problem isn't that the current_user helper method is unavailable to the second controller, it's that your current_user method is not finding a user and returning nil. Then your attempting to call the households method on the returned nil object.

If the current_user method was not available in that controller you would see an error message such as:

undefined local variable or method `current_user' for #<YourController:0x1057870e8>

This means you have a flaw in the flow of your logic. Either the session parameter hasn't been set yet by the time it hits that method, or it was set but to a user_id that doesn't exist.

Try adding:

def home
  @households = (logged_in? ? current_user.households.all : nil)
  @household  = (logged_in? ? current_user.households.build : nil)

  respond_to do |format|
    format.html
    format.xml { render xml: @households }
  end
end

Replacing nil with whatever your fallback data should be.

answered Sep 17, 2012 at 22:22

Luke Mueller

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2 Comments

kypalmer Over a year ago

I'm not sure what type of fallback data should be there. Right now anything I put in gives me this error: campaign_app/app/helpers/sessions_helper.rb:17: syntax error, unexpected ')', expecting keyword_end

Luke Mueller Over a year ago

Well that's assuming it's ok the hit that method without a current user. Check your webrick server logs and look carefully at when ur setting the session param in relation to when that home method is hit. As for the syntax error, just remove the parens entirely, you don't really need them.

Luke Mueller · Accepted Answer · 2012-09-17 23:06:07Z

1

Might have just spotted why your current_user method is returning nil. Your searching by session not by ID. Try this:

def current_user
  @current_user ||= User.find(session[:user_id])
end

OR if you want to be more explicit:

def current_user
  @current_user ||= User.find_by_id(session[:user_id])
end

answered Sep 17, 2012 at 23:06

Luke Mueller

2632 silver badges8 bronze badges

Comments

kypalmer · Accepted Answer · 2012-09-18 14:19:42Z

0

I hate to jump on here and answer my own question, but I had trouble with this for so long that I want anyone having the same problem to be able to figure this one out. This turned out to be a mixture of many of the answers on this page as well as Michael Hartl's tutorial book. I was using helper methods, but had not included the helpers in application_controller.rb:

class ApplicationController < ActionController::Base
  include ControllerAuthentication
  include SessionsHelper
...

I also was verifying that a user was signed in to display them dynamic content in my view home.html.erb:

<% if signed_in? %>
  <!-- show the user dashboard -->
...

But I had no such verification on the controller static_pages_controller.rb:

def home
  if signed_in?
  @households = current_user.households.all 
  @household  = current_user.households.build 
end

Because of all of this, the error:

undefined method `households' for nil:NilClass

was thrown continually while a user was not signed in and was trying to visit the root_path. In other cases I could have redirected, but I wanted the user to see dynamic content on the home page if they were logged in and a static landing page if they were not.

Thanks everyone for the help!

answered Sep 18, 2012 at 14:19

kypalmer

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1 Comment

xiy Over a year ago

This is definitely the right way to go. I was going to say that, by the time the logic reaches the home action there shouldn't really be a question of "is the user logged in or not?". I would establish that fact before I even allowed access to resources which in themselves are restricted (YourController#home in this case). It's like letting someone into a members club and only checking their members card when they're inside, if you see what I mean. Nice to see someone learn by doing, well done :)

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