Saving class with array property with YAML

ruby-talk
1

Hello

I'm new to Ruby and unfortuantly I can't find an example anywhere to the following problem.

I have the following class:

class Article
   attr_accessor :author
   attr_accessor :title

   def inititialize(author, title)
     @autor = author
     @title = title
   end
end

class Book
   attr_accessor :year
   attr_accessor :volume
   attr_accessor :articles # array of articles

   def initialize(year, volume)
     @year = year
     @volume = volume
     @articles = Array.new
   end

   def insert(author, title)
     @articles.push(Article.new(author,title))
   end
end

class Bookshelf
...
end

#create book
testbook = Book.new(2007, 1)

#insert 2 articles into the book
testbook.insert("Martin Mueller", "Confessing that I'm a Ruby Dummy")
testbook.insert("Hillary Clinton", "Elect me and Ruby will save our planet")

#write Book to YAML
File.open("testbook.yaml", "w") {|f| YAML.dump(testbook, f)}

···

-----------------------

My question is: how can I bring Ruby to save also the Array??

I played around with to_yaml_properties but without success.

thanks a lot for any hint!

Best regards,
Martin.

2

Hi Martin, you have a few issues in your code, I will go through them for you.

Hello

I'm new to Ruby and unfortuantly I can't find an example anywhere to the
following problem.

I have the following class:

class Article
   attr_accessor :author
   attr_accessor :title

   def inititialize(author, title)

this should be spelled initialize, might be why you are getting an
argument error

     @autor = author
     @title = title
   end
end

class Book
   attr_accessor :year
   attr_accessor :volume
   attr_accessor :articles # array of articles

   def initialize(year, volume)
     @year = year
     @volume = volume
     @articles = Array.new
   end

   def insert(author, title)
     @articles.push(Article.new(author,title))
   end
end

class Bookshelf
...
end

#create book
testbook = Book.new(2007, 1)

#insert 2 articles into the book
testbook.insert("Martin Mueller", "Confessing that I'm a Ruby Dummy")
testbook.insert("Hillary Clinton", "Elect me and Ruby will save our planet")

#write Book to YAML

you also need to:
require 'yaml'

File.open("testbook.yaml", "w") {|f| YAML.dump(testbook, f)}

-----------------------

My question is: how can I bring Ruby to save also the Array??

I played around with to_yaml_properties but without success.

thanks a lot for any hint!

Best regards,
Martin.

Now it saves teh articles array

···

On 2/3/07, Martin Müller <usenet@martinopia.com> wrote:

--
Chris Carter
concentrationstudios.com
brynmawrcs.com

3

First you should correct spelling errors of your initialize methods. After you did that, you don't have to do anything:

irb(main):049:0> testbook = Book.new(2007, 1)
=> #<Book:0x4918fe4 @year=2007, @articles=, @volume=1>
irb(main):050:0> testbook.insert("Martin Mueller", "Confessing that I'm a Ruby Dummy")
=> [#<Article:0x4914e94 @title="Confessing that I'm a Ruby Dummy", @autor="Martin Mueller">]
irb(main):051:0> testbook.insert("Hillary Clinton", "Elect me and Ruby will save our planet")
=> [#<Article:0x4914e94 @title="Confessing that I'm a Ruby Dummy", @autor="Martin Mueller">, #<Article:0x491090c @title=
"Elect me and Ruby will save our planet", @autor="Hillary Clinton">]
irb(main):052:0> puts testbook.to_yaml
--- !ruby/object:Book
articles:
- !ruby/object:Article
   autor: Martin Mueller
   title: Confessing that I'm a Ruby Dummy
- !ruby/object:Article
   autor: Hillary Clinton
   title: Elect me and Ruby will save our planet
volume: 1
year: 2007
=> nil
irb(main):053:0>

Btw, your Book#insert does two things: create an Article and append that to your Book. It's a convenient method. You don't really need that method since you make #articles available anyway so you could as well do:

testbook.articles << Article.new( "Martin", "I am a Ruby" )

Kind regards

  robert

···

On 03.02.2007 17:13, Martin Müller wrote:

Hello

I'm new to Ruby and unfortuantly I can't find an example anywhere to the following problem.

I have the following class:

class Article
  attr_accessor :author
  attr_accessor :title

  def inititialize(author, title)
    @autor = author
    @title = title
  end
end

class Book
  attr_accessor :year
  attr_accessor :volume
  attr_accessor :articles # array of articles

  def initialize(year, volume)
    @year = year
    @volume = volume
    @articles = Array.new
  end

  def insert(author, title)
    @articles.push(Article.new(author,title))
  end
end

class Bookshelf
...
end

#create book
testbook = Book.new(2007, 1)

#insert 2 articles into the book
testbook.insert("Martin Mueller", "Confessing that I'm a Ruby Dummy")
testbook.insert("Hillary Clinton", "Elect me and Ruby will save our planet")

#write Book to YAML
File.open("testbook.yaml", "w") {|f| YAML.dump(testbook, f)}

-----------------------

My question is: how can I bring Ruby to save also the Array??

I played around with to_yaml_properties but without success.

thanks a lot for any hint!

4

Thank you both for your kind help!

BR/Martin.