Validating boolean value in Rspec and Rails

Question

I'm pretty confused how to validate boolean values in Rspec and Rails. I understand everything except for false and nil are taken as true in Ruby. But when I use MySQL with Rails, it uses 1 for true and 0 for false (if my understanding is correct).

I have the following model spec. I'd like to test boolean value for superuser attribute.

• How can I write specs here?
• How can I write implementation code here?

• Are my specs and implementation code specific to a specific database (like MySQL and PostgreSQL)?

  require 'spec_helper'
  describe User do
    before(:each) do
      @valid_attributes = {
        :username => "mike",
        :password => "super_encryped_password",
        :email => "[email protected]",
        :superuser => true
      }  
    end
  
    it "should create a new instance given valid attributes" do
      User.create!(@valid_attributes)
    end
  
    it "should have true or false for superuser" do
      @valid_attributes[:superuser] = "hello"
      User.new(@valid_attributes).should have(1).error_on(:superuser)
    end
  end
  

Answer 1

This is a great discussion with some important points: Rails validates boolean fields automatically, a false value will cause "presence" validations to fail, and a custom validation looking explicitly for true false settings is needed if you want to make sure a boolean field is not nil but has a genuine true or false value.

A quick update for Rails 3.x is the :inclusion helper:

http://guides.rubyonrails.org/active_record_validations_callbacks.html#inclusion

With this helper, validating that a boolean field has a true or a false value looks like this:

validates :superuser, :inclusion => {:in => [true, false], :message => 'requires a true or false value' }

The message is optional and will, as the documentation notes, default to "is not included in the list."

The consensus online seems to be not to bother validating explicitly for true or false, but to let rails take care of it. I ran into a situation, however, where the explicit validations picked up a problem in the database (MySql tinyint fields were set to 2 or 4 in length instead of 1) that caused a strange behavior. The fields could be set to true or false, but the value could not be read back out as a boolean. In other words, the Rails validation passed it through but the explicit inclusion validation flagged all of those cases where the database was misconfigured. So this might be one good reason to go to the trouble of validating those entries. Hope this helps. Charles

Answer 2

One important thing is that ActiveRecord does typecasting behind the scenes, so you do not have to worry about how your database stores boolean values. You even need not validate that a field is boolean, as long as you set that field as boolean when preparing your migration. You may want to make sure the field is not nil though, with a validates_presence_of :superuser declaration in your model class.