Ruby convert Object to Hash

Question

Let s say I have a Gift object with  name    book   amp   price   15 95  What s the best way to convert that to the Hash  name   book   price  15 95  in Ruby  not Rails  although feel free to give the Rails answer too

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You can write a very elegant solution using a functional style   class Object   def hashify     Hash instance variables map    v   v to s 1  -1  to sym  instance variable get v       end end

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Just say  current object   attributes   attributes returns a hash of any object  And it s much cleaner too

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Gift new instance values     gt    name   gt  book    price   gt 15 95

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class Gift   def to hash     instance variables map do  var         var 1  -1  to sym  instance variable get var       end to h   end end

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class Gift   def initialize      name    book       price   15 95   end end  gift   Gift new hash      gift instance variables each   var  hash var to s delete         gift instance variable get var    p hash     gt    name   gt  book    price   gt 15 95    Alternatively with each with object   gift   Gift new hash   gift instance variables each with object        var  hash  hash var to s delete         gift instance variable get var    p hash     gt    name   gt  book    price   gt 15 95

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I started using structs to make easy to hash conversions  Instead of using a bare struct I create my own class deriving from a hash this allows you to create your own functions and it documents the properties of a class   require  ostruct   BaseGift   Struct new  name   price  class Gift  lt  BaseGift   def initialize name  price      super name  price    end         more user defined methods here  end  g   Gift new  pearls   20  g to h   returns    name  gt  pearls    price  gt 20

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Implement  to hash   class Gift   def to hash     hash          instance variables each    var  hash var to s delete         instance variable get var        hash   end end   h   Gift new  Book   19  to hash

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Might want to try instance values  That worked for me

User · Answer

You can use as json method  It ll convert your object into hash    But  that hash will come as a value to the name of that object as a key  In your case      gift    gt    name    gt   book    price    gt  15 95      If you need a hash that s stored in the object use as json root  false   I think by default root will be false  For more info refer official ruby guide  http   api rubyonrails org classes ActiveModel Serializers JSON html method-i-as json

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If you are not in an Rails environment  ie  don t have ActiveRecord available   this may be helpful   JSON parse  object to json

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For Active Record Objects  module  ActiveRecordExtension   def to hash     hash       self attributes each    k v  hash k    v       return hash   end end  class Gift  lt  ActiveRecord  Base   include ActiveRecordExtension        end  class Purchase  lt  ActiveRecord  Base   include ActiveRecordExtension        end   and then just call  gift to hash   purch to hash

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Recursively convert your objects to hash using  hashable  gem  https   rubygems org gems hashable  Example  class A   include Hashable   attr accessor  blist   def initialize      blist     B new 1      b    gt  B new 2        end end  class B   include Hashable   attr accessor  id   def initialize id    id   id  end end  a   A new a to dh   or a to deep hash     blist  gt    id  gt 1     b   gt   id  gt 2

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Gift new attributes symbolize keys

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You should override the inspect method of your object to return the desired hash  or just implement a similar method without overriding the default object behaviour   If you want to get fancier  you can iterate over an object s instance variables with object instance variables

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If you need nested objects to be converted as well      fn       to hash obj        brief    Convert object to hash      return    Hash  Hash representing converted object   def to hash obj   Hash obj instance variables map    key      variable   obj instance variable get key      key to s 1  -1  to sym        if variable respond to   lt  some method gt  then         hashify variable       else         variable       end            end

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Produces a shallow copy as a hash object of just the model attributes  my hash gift   gift attributes dup   Check the type of the resulting object  my hash gift class   gt  Hash

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To do this without Rails  a clean way is to store attributes on a constant   class Gift   ATTRIBUTES     name   price    attr accessor  ATTRIBUTES  end   And then  to convert an instance of Gift to a Hash  you can   class Gift         def to h     ATTRIBUTES each with object     do  attribute name  memo        memo attribute name    send attribute name      end   end end   This is a good way to do this because it will only include what you define on attr accessor  and not every instance variable   class Gift   ATTRIBUTES     name   price    attr accessor  ATTRIBUTES     def create random instance variable      xyz   123   end    def to h     ATTRIBUTES each with object     do  attribute name  memo        memo attribute name    send attribute name      end   end end  g   Gift new g name    Foo  g price   5 25 g to h    gt    name  gt  Foo    price  gt 5 25   g create random instance variable g to h    gt    name  gt  Foo    price  gt 5 25

[ruby] Ruby convert Object to Hash

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