Rails fun with a not null constraint and a default value.

20130306225243_create_customers.rb

class CreateCustomers < ActiveRecord::Migration
  def change
    create_table :customers do |t|
      t.string  :name,       :null => false
      t.boolean :subscribed, :null => false, :default => true

      t.timestamps
    end
  end
end

bash

curl --data "customer[name]=shanon"                        http://localhost:3000/customers.json => 200
curl --data "customer[name]=shanon&customer[subscribed]=0" http://localhost:3000/customers.json => 200
curl --data "customer[name]=shanon&customer[subscribed]="  http://localhost:3000/customers.json => 500

console

Customer.create!(:name => "shanon")                     => #<Customer id: 1 ... >
Customer.create!(:name => "shanon", :subscribed => nil) => ActiveRecord::StatementInvalid
Customer.create!(:name => "shanon", :subscribed => "")  => ActiveRecord::StatementInvalid

customer.rb

class Customer < ActiveRecord::Base
  attr_accessible :name, :subscribed
end

customer_controller.rb

class CustomersController < ApplicationController
  respond_to :json
  def create
    respond_with Customer.create(params[:customer])
  end
end

how's that bad? you've deliberately specified 'nil' in the create statement. If you want to work around it in a way that doesn't throw an exception on save (but will on save!) add validates_presence_of :subscribed to your model.

I'm setting this value from parameters which means that during a rolling deploy, old forms will submit nulls. Also it would be nice if I didn't have to update all the specs, features and fixtures with this parameter,

Customer.create!(
  :subscribe => params[:subscribe]
)

Add this to your model as an interim step

before_save :set_default_subscribed

def set_default_subscribed
    self.subscribed = true if self.subscribed.nil?
end

beware that this won't work

self.subscribed ||= true

@cmaitchison yeah that works nicely. Feels like I'm fighting rails though and life would be a lot easier if I just removed the not null constraint.

Forms don't submit nulls: nulls get stripped from the incoming params by Rails. Assuming HTTP GET/POST and not JSON/XML, that is.

Oh. Wait. Yeah, I think I get it - something else is pulling it from a form params, and it's defaulting to null. Yeah. Workaround, then remove post deploy.

But that's not a bug :p

Shouldn't rails be calling to_bool when you model.this_attribute_is_a_boolean = ""?