JSONb Accessor

Adds typed jsonb backed fields as first class citizens to your ActiveRecord models. This gem is similar in spirit to HstoreAccessor, but the jsonb column in PostgreSQL has a few distinct advantages, mostly around nested documents and support for collections.

This gem is under heavy development. Please use cautiously and help us with feedback by opening issues for defects and feature requests. The current API is subject to change.

Installation

Add this line to your application’s Gemfile:

gem "jsonb_accessor"

And then execute:

$ bundle install

Usage

First we must create a model which has a jsonb column available to store data into it:

class CreateProductsTable &lt; ActiveRecord::Migration
  def change
    create_table :products do |t|
      t.jsonb :options
    end
  end
end

We can then declare the jsonb fields we wish to expose via the accessor:

class Product &lt; ActiveRecord::Base
  jsonb_accessor(
    :options,
    :count, # =&gt; value type
    title: :string,
    id_value: :value,
    external_id: :integer,
    reviewed_at: :datetime
  )
end

JSONb Accessor accepts both untyped and typed key definitions. Untyped keys are treated as-is and no additional casting is performed. This allows the freedom of dynamic values alongside the power types, which is especially convenient when saving nested form attributes. Typed keys will be cast to their respective values using the same mechanism ActiveRecord uses to coerce standard attribute columns. It’s as close to a real column as you can get and the goal is to keep it that way.

All untyped keys must be defined prior to typed columns. You can declare a typed column with type value for explicit dynamic behavior. For reference, the jsonb_accessor macro is defined thusly.

def jsonb_accessor(jsonb_attribute, *value_fields, **typed_fields)
  ...
end

There’s quite a bit more to do do and document but we’re excited to get this out there while we work on it some more.

ActiveRecord Methods Generated for Fields

class Product &lt; ActiveRecord::Base
  jsonb_accessor :data, field: :string
end

field
field=
field?
field_changed?
field_was
field_change
reset_field!
restore_field!
field_will_change!

Supported Types

The following types are supported, including typed collections:

:array,
:boolean,
:boolean_array,
:date,
:date_array,
:datetime,
:datetime_array,
:decimal,
:decimal_array,
:float,
:float_array,
:integer,
:integer_array,
:string,
:string_array,
:time,
:time_array,
:value

Support for nested types is also available but experimental at this point. If you must, you may try something like this for nested objects.

class Product &lt; ActiveRecord::Base
  jsonb_accessor(
    :options,
    nested_object: { key: :integer }
  )
end

p = Product.new
p.nested_object.key = "10"
puts p.nested_object.key #=&gt; 10

Validations

Because this gem promotes attributes nested into the JSON column to first level attributes, most validations should just work. We still have to add some testing and support around this feature but feel free to try and leave us feedback if they’re not working as expected.

Single-Table Inheritance

You can use it for STI in the same spirit as hstore_accessor, which is documented here..

Scopes

Coming soon…

Migrations

Coming soon…

jsonb supports GIN, GIST, btree and hash indexes over json column. We have plans to add migrations helpers for generating these indexes for you.

Dependencies

ActiveRecord 4.2
Postgres 9.4 (in order to use the jsonb column type).

Development

After checking out the repo, run bin/setup to install dependencies (make sure postgres is running first).

Run bin/console for an interactive prompt that will allow you to experiment.

rake will run Rubocop and the specs.

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Add tests and changes (run the tests with rake)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request

Modules

Classes