Rails - Unserializing an attribute

[pergesu]

I want to use a Runt object as an attribute for one of my classes. I can save it to the db fine, looks like...but I need to be able to use it after I pull the object from the db. Right now the attribute is just a String, but I need it to be a Runt::Intersect object. Does anyone know how I can unserialize the attribute so I can use it as an object?

[Luke Redpath]

How is it serialized in the first place? Does Rails do this automatically?

[ezmobius1]

Yeah how are you getting it into the db? Are you using serialize :foo for one of your columns in the db? That might be the easiest way. When you use a serialize statement in one of your models the object you want to store in the column gets serialized to yaml before going in and transparently gets dehydrated back into an object when it comes out.

The main limitation of this method of doing things is that your object needs to be YAML dumpable. This means no procs or lamdas. You could try to create on of your runt objects in irb or something and then dump it to yaml and reload it to see if it survives the translation. Like this:

require 'yaml'

class Foo
  attr_accessor :bar
  attr_accessor :qux
  def initialize(bar, qux)
    @bar, @qux = bar, qux
  end
end

a = Foo.new("hello", "world")
p a # => #<Foo:0x219f00 @qux="world", @bar="hello">
b = YAML.load(YAML.dump a)
p b # => #<Foo:0x444408 @qux="world", @bar="hello">

But if you try to add a proc or lamda in the mix it will not work:

require 'yaml'

class Foo
  attr_accessor :bar
  attr_accessor :qux
  def initialize(bar, qux)
    @bar, @qux = bar, lambda { qux.reverse.upcase }
  end
end

a = Foo.new("hello", "world")
p a # #<Foo:0x4160bc @qux=#<Proc:0x0041962c@(irb):38>, @bar="hello">
a.qux.call # => "DLROW"
b = YAML.load(YAML.dump a)
TypeError: allocator undefined for Proc
        from /usr/lib/ruby/1.8/yaml.rb:347:in `allocate'
        from /usr/lib/ruby/1.8/yaml.rb:347:in `object_maker'
        from /usr/lib/ruby/1.8/yaml/rubytypes.rb:36
        from /usr/lib/ruby/1.8/yaml/rubytypes.rb:34:in `call'
        from (irb):46:in `transfer'
        from /usr/lib/ruby/1.8/yaml.rb:119:in `load'
        from /usr/lib/ruby/1.8/yaml.rb:119:in `load'
        from (irb):46

Hope that helps some.

-Ezra

[pergesu]

I didn't do anything in particular. I just created a bytea column (BLOB for MySQL guys), and did
myrecord.timex = intersectobject
myrecord.save

So I want to some how be able to use myrecord.timex as a Runt::Intersect object (which is what it's saved as) instead of a String. Right now if I do
myrecord.timex.include? it thinks that timex is a String and is doing the String#include?, which isn't going to work for me. I need to use Runt::Intersect#include?

[Luke Redpath]

I think you need to use the Rails serialize helper as mentioned above to serialize/deserialise the object.

[Radley]

I think what is getting saved is intersectobject.to_s

[xmitchx]

Just a note: You don't need to "require 'yaml'" as its built directly into rails.

[pergesu]

I have
serialize :timex, Runt::Intersect

In my Event model. But it's still coming out as a string.

Is it even possible to make an object an attribute? I would think so..that's why we have binary field types in the db, right?