Module: MetaHash

Defined in:
lib/metahash.rb,
lib/metahash/version.rb

Constant Summary collapse

VERSION = 
"1.2.0"

Instance Method Summary collapse

Instance Method Details

#has_metadata(serialized_field = "metadata", serializer: JSON) ⇒ Object

When an active record object is loaded, convert to Metadata. If for whatever reason we lose this Metadata class, we can read the hash by creating class Metadata < Hash; end

Parameters:

  • serialized_field (Symbol) (defaults to: "metadata") —

    name of the field to convert to Metadata



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# File 'lib/metahash.rb', line 13

def has_metadata( serialized_field = "metadata", serializer: JSON )
  # tell Active Record that the field is going to be JSON
  # serialized, because JSON > YAML
  serialize serialized_field, serializer

  after_initialize do |record|
    # first check the type of the field
    # proceed if hash, abort if Metadata
    if record.has_attribute?(serialized_field)
      if [ Hash, NilClass ].include?( record.send( serialized_field ).class )
        # alias the old method / field
        backup_name = "#{serialized_field}_original".to_sym

        # alias_method backup_name, serialized_field
        record.define_singleton_method( backup_name, record.method( serialized_field ) )

        # name the metadata accessor the same as the original field
        # rails should automatically serialize this on save
        initial_value = record.send( backup_name) || {}
        record.send( "#{serialized_field}=", Metadata.new( initial_value ) )
      end
    end
  end

  build_save_hooks( serialized_field )
end