json_api.rb

# Serializer classes
class Job < JSONAPISerializer
  attributes :name
end

class PersonSerializer < JSONAPISerializer
  attributes :name, :age
  has_many :jobs, path: :current_jobs, included: true
end


# simple object
person = OpenStruct.new({id: 1, name: 'Cata', age: '20', current_jobs: [{name: 'Programer', id: 1}]})


# call from a controller
render :json, PersonSerializer.new(person)


=begin
# Output
{
  "data": [{
    "type": "persons",
    "id": "1",
    "attributes": {
      "name": "Cata",
      "age": 20
    },
    "relationships": {
      "jobs": [
        {
          "data": {"id": "1", "type": "jobs"}
        }
      ]
    }
  }],
  "included": [
    {
      "type": "jobs",
      "id": "1",
      "attributes": {
        "name": "Programer"
      }
    }
  ]
}
=end

# call from a  controller. but now we want only the name in the response, without the jobs and age 
render :json, PersonSerializer.new person do
  attributes :name
  has_many :jobs, disabled: true
end

=begin
{
  "data": [{
    "type": "persons",
    "id": "1",
    "attributes": {
      "name": "Cata"
    }
  }]
}
=end



# Normalizer
class PersonNormalizer < JSONAPINormalizer
  attributes :name

  has_many :jobs, path: :current_jobs, normalizer: 'JobsNormalizer'

  nested_attibute :address do
      attributes :city
    
      nested_attibute :street do
        attributes :postal_code
      end  
  end   
end

class JobsNormalizer < JSONAPINormalizer
  attributes :name
end 


=begin

# Input
# POST /persons

{
  "data": [{
    "type": "persons",
    "id": "1",
    "attributes": {
      "name": "Cata",
      "age": 20
      }
    },
    "relationships": {
      "jobs": [
        {
          "data": {"id": "1", "type": "jobs"}
        }
      ]
    }
  }],
  "included": [
    {
      "type": "jobs",
      "id": "1",
      "attributes": {
        "name": "Smenar"
      }
    }
  ]
}
=end


# override the normalizer, not to read the jobs
def create
  person_attributes = PersonNormalizer.new params do
    attributes :name, :age

    has_many :jobs, disabled: true
  end

  person = Person.new(person_attributes.person)

  jobs = person_attributes.jobs.map do |attr|
    Job.new(attr)
  end

  transaction do
    person.save
    jobs.each(&:save)
  end
end


def create
  person_attributes = PersonNormalizer.new params
  
  person = Person.new(person_attributes.person)
  jobs = person_attributes.jobs.map do |attr|
    Job.new(attr)
  end
  
  transaction do
    person.save
    jobs.each(&:save)
  end
end