module ActiveRecord::Store - activerecord-4.2.5.2 Documentation

# module ActiveRecord::Store

Store gives you a thin wrapper around serialize for the purpose of storing hashes in a single column. It's like a simple key/value store baked into your record when you don't care about being able to query that store outside the context of a single record.

You can then declare accessors to this store that are then accessible just like any other attribute of the model. This is very helpful for easily exposing store keys to a form or elsewhere that's already built around just accessing attributes on the model.

Make sure that you declare the database column used for the serialized store as a text, so there's plenty of room.

You can set custom coder to encode/decode your serialized attributes to/from different formats. JSON, YAML, Marshal are supported out of the box. Generally it can be any wrapper that provides `load` and `dump`.

NOTE - If you are using PostgreSQL specific columns like `hstore` or `json` there is no need for the serialization provided by `store`. Simply use `store_accessor` instead to generate the accessor methods. Be aware that these columns use a string keyed hash and do not allow access using a symbol.

Examples:

    class User < ActiveRecord::Base
      store :settings, accessors: [ :color, :homepage ], coder: JSON
    end

    u = User.new(color: 'black', homepage: '37signals.com')
    u.color                          # Accessor stored attribute
    u.settings[:country] = 'Denmark' # Any attribute, even if not specified with an accessor

    # There is no difference between strings and symbols for accessing custom attributes
    u.settings[:country]  # => 'Denmark'
    u.settings['country'] # => 'Denmark'

    # Add additional accessors to an existing store through store_accessor
    class SuperUser < User
      store_accessor :settings, :privileges, :servants
    end

The stored attribute names can be retrieved using `stored_attributes`.

    User.stored_attributes[:settings] # [:color, :homepage]

## Overwriting default accessors¶ ↑

All stored values are automatically available through accessors on the Active Record object, but sometimes you want to specialize this behavior. This can be done by overwriting the default accessors (using the same name as the attribute) and calling `super` to actually change things.

    class Song < ActiveRecord::Base
      # Uses a stored integer to hold the volume adjustment of the song
      store :settings, accessors: [:volume_adjustment]

      def volume_adjustment=(decibels)
        super(decibels.to_i)
      end

      def volume_adjustment
        super.to_i
      end
    end

### Attributes

local_stored_attributes[RW]

### Protected Instance Methods

read_store_attribute(store_attribute, key) click to toggle source

    # File lib/active_record/store.rb, line 120
    def read_store_attribute(store_attribute, key)
      accessor = store_accessor_for(store_attribute)
      accessor.read(self, store_attribute, key)
    end

write_store_attribute(store_attribute, key, value) click to toggle source

    # File lib/active_record/store.rb, line 125
    def write_store_attribute(store_attribute, key, value)
      accessor = store_accessor_for(store_attribute)
      accessor.write(self, store_attribute, key, value)
    end

### Private Instance Methods

store_accessor_for(store_attribute) click to toggle source

    # File lib/active_record/store.rb, line 131
    def store_accessor_for(store_attribute)
      type_for_attribute(store_attribute.to_s).accessor
    end