convert hash to object

Question

I am trying to convert hash and nested hashes to objects.

so far first hash object is converted successfully by this code:

class Hashit
  def initialize(         


        

Answer 1

Ruby has an inbuilt data structure OpenStruct to solve something like this. Still, there is a problem. It is not recursive. So, you can extend OpenStruct class like this:

# Keep this in lib/open_struct.rb
class OpenStruct
  def initialize(hash = nil)
    @table = {}
    if hash
      hash.each_pair do |k, v|
        k = k.to_sym
        @table[k] = v.is_a?(Hash) ? OpenStruct.new(v) : v
      end
    end
  end

  def method_missing(mid, *args) # :nodoc:
    len = args.length
    if mname = mid[/.*(?==\z)/m]
      if len != 1
        raise ArgumentError, "wrong number of arguments (#{len} for 1)", caller(1)
      end
      modifiable?[new_ostruct_member!(mname)] = args[0].is_a?(Hash) ? OpenStruct.new(args[0]) : args[0]
    elsif len == 0 # and /\A[a-z_]\w*\z/ =~ mid #
      if @table.key?(mid)
        new_ostruct_member!(mid) unless frozen?
        @table[mid]
      end
    else
      begin
        super
      rescue NoMethodError => err
        err.backtrace.shift
        raise
      end
    end
  end
end

and remember to require 'open_struct.rb' next time you want to use OpenStruct.

Now you can do something like this:

person = OpenStruct.new
person.name = "John Smith"
person.age  = 70
person.more_info = {interests: ['singing', 'dancing'], tech_skills: ['Ruby', 'C++']}

puts person.more_info.interests
puts person.more_info.tech_skills

Answer 2

Another way is to use JSON and OpenStruct, which are standard ruby libs:

irb:
> require 'JSON'
=> true

> r = JSON.parse({a: { b: { c: 1 }}}.to_json, object_class: OpenStruct)
=> #<OpenStruct a=#<OpenStruct b=#<OpenStruct c=1>>>

> r.a.b.c
=> 1

Answer 3

You could check the type on v when you initialize the object and call new to get a new Hashit when it is a another hash.

class Hashit
  def initialize(hash)
    hash.each do |k,v|
      self.instance_variable_set("@#{k}", v.is_a?(Hash) ? Hashit.new(v) : v)
      self.class.send(:define_method, k, proc{self.instance_variable_get("@#{k}")})
      self.class.send(:define_method, "#{k}=", proc{|v| self.instance_variable_set("@#{k}", v)})
    end
  end
end

and the resulting snippet from before would be:

h = Hashit.new({a: '123r', b: {c: 'sdvs'}})
=> #<Hashit:0x007fa71421a850 @a="123r", @b=#<Hashit:0x007fa71421a5a8 @c="sdvs">>

Answer 4

If I understand the question correctly, this should do it:

class Hashit
  def initialize(hash)
    convert_to_obj(hash)
  end

  private

  def convert_to_obj(h)
    h.each do |k,v|
      self.class.send(:attr_accessor, k)
      instance_variable_set("@#{k}", v) 
      convert_to_obj(v) if v.is_a? Hash
    end
  end
end

h = Hashit.new( { a: '123r',
      b: { c: 'sdvs', d: { e: { f: 'cat' }, g: {h: 'dog'} } } })
  #=> #<Hashit:0x000001018eee58 @a="123r",
  #     @b={:c=>"sdvs", :d=>{:e=>{:f=>"cat"}, :g=>{:h=>"dog"}}},
  #       @c="sdvs", @d={:e=>{:f=>"cat"}, :g=>{:h=>"dog"}},
  #       @e={:f=>"cat"}, @f="cat", @g={:h=>"dog"}, @h="dog">
h.instance_variables
  #=> [:@a, :@b, :@c, :@d, :@e, :@f, :@g, :@h]
Hashit.instance_methods(false)
  #=> [:a, :a=, :b, :b=, :c, :c=, :d, :d=, :e, :e=, :f, :f=, :g, :g=, :h, :h=]
h.d
  #=> {:e=>{:f=>"cat"}}
h.d = "cat"
h.d
  #=> "cat"

Answer 5

You need to add recursivity:

class Hashit
  def initialize(hash)
    hash.each do |k,v|
      self.instance_variable_set("@#{k}", v.is_a?(Hash) ? Hashit.new(v) : v)
      self.class.send(:define_method, k, proc{self.instance_variable_get("@#{k}")})
      self.class.send(:define_method, "#{k}=", proc{|v| self.instance_variable_set("@#{k}", v)})
    end
  end
end

h = Hashit.new({a: '123r', b: {c: 'sdvs'}})
# => #<Hashit:0x007fa6029f4f70 @a="123r", @b=#<Hashit:0x007fa6029f4d18 @c="sdvs">>

Answer 6

You can use OpenStruct http://ruby-doc.org/stdlib-2.0.0/libdoc/ostruct/rdoc/OpenStruct.html

user = OpenStruct.new({name: "Jimmy Cool", age: "25"})
user.name #Jimmy Cool
user.age #25