Rails 5 Attributes API + JSONb Postgres columns

As of when I'm writing this (Jan 2017), support for using ActiveRecord `store` with Postgres JSONb columns is [a bit of shit-show](https://github.com/rails/rails/issues/26991#issuecomment-272280143). I'm planning to help fix it as soon as I have some time to spare, but for the moment if you want a better way of supporting these valuable column types in your Rails 5 app, use the new Attributes API. Plus get much improved performance with the Oj gem.

Here's how to make it work. First, define a `:jsonb` type to replace the native one.

```ruby
class JsonbType < ActiveModel::Type::Value
  include ActiveModel::Type::Helpers::Mutable

  def type
    :jsonb
  end

  def deserialize(value)
    if value.is_a?(::String)
      Oj.load(value) rescue nil
    else
      value
    end
  end

  def serialize(value)
    if value.nil?
      nil
    else
      Oj.dump(value)
    end
  end

  def accessor
    ActiveRecord::Store::StringKeyedHashAccessor
  end
end
```

Next, register it in an initializer.

```ruby
ActiveRecord::Type.register(:jsonb, JsonbType, override: true)
```

Note that the `JsonbType` class will need to be somewhere in your loadpath.

Now just declare the attribute at the top of your ActiveRecord model like this:

```ruby
class User < ApplicationRecord
  attribute :preferences, :jsonb, default: {}
```

obie-fernandez
January 22, 2017