Question

I have the following models:

class Post < ActiveRecord::Base
    has_and_belongs_to_many :countries
end

class User < ActiveRecord::Base 
    has_many :entitlements
    has_many :countries, :through => :entitlements
end

Posts on the Post index page must have at least one country that is the same as one of the Users’ countries.

I have tried various scopes in my models and lengthy controller code but I can’t figure out how to check what should be a simple relationship: whether at least one item in Post.countries exists in User.countries.

Any help greatly received.

UPDATED:

Ok, so I’ve got the following in my controller:

  def index
    @user = current_user
    @user.countries.each do |user_country|  
       @user_country_posts += Country.find(user_country.id).posts
    end
    @posts = @user_country_posts
  end

Which is iterating through the user.countries and finding each post for those countries. But when I run it I get:

NoMethodError: undefined method `+' for nil:NilClass

Any ideas what I’m doing wrong?

Answer 1

The problem is that you’re trying to use the @user_country_posts instance variable which was not defined before, so its value is nil.

At the line:

@user_country_posts += Country.find(user_country.id).posts

You’re actually calling the + method on the @user_country_posts variable, which is equivalent therefore with calling + on a nil.

Try to initialize the variable in the beginning of the method, like:

@user_country_posts = []