Object to_json with all properties

Question

I have some classes that sended to a API thru HTTP and I need to be exported to json with all properties (including nils).

I have a class like this:

class Customer

  JSON.mapping(
    id:    UInt32 | Nil,
    name:  String | Nil,
    email: String | Nil,
    token: String
  )

  def initialize @token
  end
end

When I create a instance of Customer and export to json I retrieve unexpected result.

c = Customer.new "FULANITO_DE_COPAS"
puts c.to_json

# Outputs
{"token":"FULANITO_DE_COPAS"}

# I expect
{"id":null,"name":null,"email":null,"token":"FULANITO_DE_COPAS"}

How to force to to_json function to export porperties class totally?

Answer 1

Use emit_null:

class Customer

  JSON.mapping(
    id:    {type: UInt32?, emit_null: true},
    name:  {type: String?, emit_null: true},
    email: {type: String?, emit_null: true},
    token: String
  )

  def initialize(@token)
  end
end

c = Customer.new "FULANITO_DE_COPAS"
c.to_json #=> {"id":null,"name":null,"email":null,"token":"FULANITO_DE_COPAS"}