Converter gem

Latest updates

1. Merge convert and convert_back to one method (convert)
2. Add default lambda creation for inner conversion (converting the inner attribute using the Converter, see down the page)
3. Add convert_to instance method to class that includes Converter module
4. Add copy_to instance method to class that includes Converter module
5. Add copy method to Converter module
6. Add clone instance method to class that includes Converter module
7. Add clone method to Converter module

Getting started

The first class you create should bea normal class like this:

class Person
  attr_accessor :fname
  attr_accessor :last_name
  attr_accessor :country_name
  attr_accessor :remark
  attr_accessor :city_name
  attr_accessor :phone_number
  attr_accessor :cash_as_int
  attr_accessor :onlyPersonAttribute
end

In the second class you should use attr_converter instead of attr_accessor, this allows Converter to recognize which attributes it should convert.

you can specify various of properties with "attr_converter":

1. The target accessor name(if it's different from the source accessor name)

2. A lambda used to convert data from the source to the target(if they are not of the same class)

3. A lambda used to convert data from the target to the source(if they are not of the same class)

Here an example of PersonDto:

class PersonDto
 include Converter

  # This is a declaration of attr_converter that describe "first_name" accessor of PersonDTO class
  #  and maps it to "fname" accessor of Person class
  attr_converter :first_name, :fname

 # The declarations in this section describe an accessor of PersonDTO class
 #  and maps it to accessor with the same name on Person class
  attr_converter :last_name
  attr_converter :country_name
  attr_converter :remark
  attr_converter :city_name
  attr_converter :phone_number

  # This is a declaration of attr_converter that describe "money_as_string" accessor
  # and maps it to "cash_as_int" access, but also specify converter to convert this data types.
  attr_converter :money_as_string, :cash_as_int, lambda { |v| v.to_f.to_int}, lambda { |v| v.to_s }
  attr_accessor :onlyPersonDtoAttribute
end

If we will create instance of PersonDTO:

    p_dto = PersonDto.new
    p_dto.first_name = 'Robert'
    p_dto.last_name = 'De niro'
    p_dto.country_name = 'Lala land'
    p_dto.city_name = 'a city name'
    p_dto.remark = 'good actor'
    p_dto.phone_number = '65432165498'
    p_dto.money_as_string = '321654987'
    p_dto.onlyPersonDtoAttribute = 'lalala'

Result:

 => [#PersonDto:0x2d3cac8 @first_name="Robert", @last_name="De niro", @country_name="Lala land",
 @city_name="a city name", @remark="good actor", @phone_number="65432165498",
 @money_as_string="321654987", @onlyPersonDtoAttribute="lalala"}

we could now convert it to Person:

p = p_dto.convert_to Person

Result:

 => [#Person:0x2d3c9d8 @fname="Robert", @last_name="De niro", @country_name="Lala land",
  @city_name="a city name", @remark="good actor", @phone_number="65432165498",
  @cash_as_int=321654987, @onlyPersonAttribute="asdasdasd"}

To Convert from Preson to PersonDTO user ConvertBack:

p_dto = Converter.convert(p, PersonDto)

Result:

=> [#PersonDto:0x2d3c4e
         0 @first_name="Robert", @last_name="De niro", @country_name="Lala land", @city_name="a city name",
         @remark="good actor", @phone_number="65432165498", @money_as_string="321654987"}

Getting Deeper

We can take Converter module into extreme by converting entire graph of objects.

Lets create a Dog class:

class Dog
  attr_accessor :name
  attr_accessor :age
end

and extend Person class to include dog:

class Person
    attr_accessor dog
end

now we should do the same with PersonDto:

class dogDTO
    attr_converter :dog_name, :name
     attr_converter :age
end

class PersonDTO
    # This assign the types of dogDto to DogDto and dog to Dog
    # and it will allow the converter to convert those type automatically!
    attr_converter :dogDTO, :dog, :DogDto, :Dog
end

Lets Convert them!

 p_dto = PersonDto.new
 p_dto.first_name = 'Robert'
 p_dto.last_name = 'De niro'
 p_dto.country_name = 'Lala land'
 p_dto.city_name = 'a city name'
 p_dto.remark = 'good actor'
 p_dto.phone_number = '65432165498'
 p_dto.money_as_string = '321654987'
 p_dto.onlyPersonDtoAttribute = 'lalala'
 p_dto.dogDTO = DogDTO.new
 p_dto.dogDTOd.dog_name = "papi"
 p_dto.dogDTOd.age=7

Result:

 => [#PersonDto:0x2be8fb8 @first_name="Robert", @last_name="De niro", @country_name="Lala land",
                                                   @city_name="a city name", @remark="good actor", @phone_number="65432165498",
                                                   @money_as_string="321654987", @onlyPersonDtoAttribute="lalala",
                                                   @dogDTO=#DogDTO:0x2be8e98 @age=7, @dog_name="papi"}

we could now convert it to Person:

p = p_dto.convert_to Person)

Result:

 => {#Person:0x2be8e68 @fname="Robert", @last_name="De niro", @country_name="Lala land", @city_name="a city name",
                                             @remark="good actor", @phone_number="65432165498", @cash_as_int=321654987,
                                             @onlyPersonAttribute="asdasdasd", @dog=#Dog:0x2be8880 @age=7, @name="papi"}

To Convert from Preson to PersonDTO user ConvertBack:

p_dto = Converter.convert(p, PersonDto)

Result:

=> [#PersonDto:0x2be86e8 @first_name="Robert", @last_name="De niro", @country_name="Lala land",
                                                  @city_name="a city name", @remark="good actor", @phone_number="65432165498",
                                                  @money_as_string="321654987", @dog=#DogDTO:0x2bace98 @age=7, @dog_name="papi"}

What about Circular pointing?

Lets say dog has accessor to his person:

class dogDTO
      attr_converter :dog_name, :name
      attr_converter :age
      attr_converter :personDto
end

class dog
      attr_converter :name, :dog_name
      attr_converter :age
      attr_converter :person
end

now what will happend? well Converter has a support for it, the result of the conversion will do the expected:

  p = p_dto.convert_to Person    

Result:

   => {#Person:0x2be8e68 @fname="Robert", @last_name="De niro", @country_name="Lala land", @city_name="a city name",
                                                 @remark="good actor", @phone_number="65432165498", @cash_as_int=321654987,
                                                 @onlyPersonAttribute="asdasdasd", @dog=#Dog:0x2be8880 @age=7, @name="papi, @person=#Person:0x2be8e68 ..."}