Simple hash serlializable object

rubyonrails-core
1

I frequently find the need to have an object with specific attributes, preferably initializable with a code block and/or a hash, that I also want serializable/deserializable to a hash.

Example:

class Foo   attr_accessor :bar, :none end

foo = Foo.new do |f|   f.bar = true   f.none = false end

puts s = foo.to_hash

{ :bar => true, :none => false}

foo = Foo.from_hash(s)

Of course I could write a library to do this, but it seems obvious enough that it would exist. Am I missing it?

2

Hi,

Maybe something like the following using OpenStruct?

require "ostruct"

class HashableStruct < OpenStruct    def self.from_hash(hash)      new(hash)    end

   def to_hash      @table    end end

f = HashableStruct.from_hash(:bar => true, :none => false) p f # => #<HashableStruct bar=true, none=false> p f.to_hash # => {:bar=>true, :none=>false}

I don't see the benefit of using a block though, it only adds another
line.

HTH, Eloy

3

Thanks for the suggestion. That looks like what I need.

The benefits of the block are that you are writing to the object instead of a hashtable, so incorrect attributes are caught sooner. It also allows more flexibility in the code, i.e. everything doesn't have to be one statement so you can do loops, conditionals, etc.

4

Well, ok, except it doesn't catch invalid attributes since you can't restrict them. Kind of icky but it works.

5

I think that Struct might be your best bet: https://gist.github.com/afe18b5713b036e2324f

It’ll disallow invalid keys, plus, is way faster than OpenStruct.

Pat

6

Pat, thanks for that great example!