Integrate with Active Record's .serialize

[seanpdoyle]

Define ActiveResource::Base.dump and ActiveResource::Base.load to support passing classes directly to serialize as the :coder option:

Writing to String columns

Encodes Active Resource instances into a string to be stored in the database. Decodes strings read from the database into Active Resource instances.

class User < ActiveRecord::Base
  serialize :person, coder: Person
end

class Person < ActiveResource::Base
  schema do
    attribute :name, :string
  end
end

user = User.new
user.person = Person.new name: "Matz"
user.person_before_type_cast # => "{\"name\":\"Matz\"}"

Writing string values incorporates the Base.format:

Person.format = :xml

user.person = Person.new name: "Matz"
user.person_before_type_cast # => "<?xml version=\"1.0\" encoding=\"UTF-8\"?><person><name>Matz</name></person>"

Instances are loaded as persisted when decoded from data containing a primary key value, and new records when missing a primary key value:

user.person = Person.new
user.person.persisted? # => false

user.person = Person.find(1)
user.person.persisted? # => true

Writing to JSON and JSONB columns

class User < ActiveRecord::Base
  serialize :person, coder: ActiveResource::Coder.new(Person, :serializable_hash)
end

class Person < ActiveResource::Base
  schema do
    attribute :name, :string
  end
end

user = User.new
user.person = Person.new name: "Matz"
user.person_before_type_cast # => {"name"=>"Matz"}

user.person.name # => "Matz"

The ActiveResource::Coder class

By default, #dump serializes the instance to a string value by calling ActiveResource::Base#encode:

user.person_before_type_cast # => "{\"name\":\"Matz\"}"

To customize serialization, pass the method name or a block as the second argument:

person = Person.new name: "Matz"

coder = ActiveResource::Coder.new(Person, :serializable_hash)
coder.dump(person) # => {"name"=>"Matz"}

coder = ActiveResource::Coder.new(Person) { |person| person.serializable_hash }
coder.dump(person) # => {"name"=>"Matz"}