Question

I have looked and looked, but I cannot find a method that will allow me to select a specific column based on a single condition (that does not involve a string query). The condition is arbitrary, but the column name is always the same. Below is my most recent (and desperate) attempt to better illustrate what I am trying to do.

@notExists = Company.select("name").where("name = ?", :company)

Ok, the query was correct, I was forgetting to use the ‘=>’ in the below code. However, that now yeilds an error because :company is evaluating to be ‘company’. According to the list of params in the server output window, its value is ‘sample’.

Edit: full content

 class User < ActiveRecord::Base
   # Include default devise modules. Others available are:
   # :token_authenticatable, :confirmable, :lockable and :timeoutable

   # Setup accessible (or protected) attributes
   attr_accessible :email, :password, :password_confirmation, :remember_me, :company

   validates :company, :presence => true
   devise :database_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable, :timeoutable

   after_save :correspond


   def correspond
     @notExists = Company.select("name").where("name = ?", :company)

     if @notExists.empty?
       c = Company.new(:name => :company)
       c.save
     end
   end

 end

To see the full solution to this issue, please see dmarkow’s answer below. One change was necessary to make it tick:

def correspond
  c = Company.find_or_create_by_name(self.company)
end

Answer 1

The only thing that is preventing your code from working is that you’re trying to use :company which translates as a string instead of a variable.

Edit:

Your correspond method should be defined with a parameter and the first line of the method should use that parameter like so:

def correspond(user)
  @notExists = Company.select("name").where("name = ?", user.company)

However, this is a much cleaner way of doing this — it will only create the company if it doesn’t exist:

def correspond(user)
  c = Company.find_or_create_by_name(user.company)
end