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A collection of decoupled drop-in modules for Ohm

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README.markdown

ohm-contrib

A collection of drop-in modules for Ohm. Read the full documentation at http://labs.sinefunc.com/ohm-contrib.

List of modules

  1. Ohm::Boundaries
  2. Ohm::Callbacks
  3. Ohm::Timestamping
  4. Ohm::ToHash
  5. Ohm::WebValidations
  6. Ohm::NumberValidations
  7. Ohm::ExtraValidations
  8. Ohm::Typecast
  9. Ohm::Locking

Example usage

require 'ohm'
require 'ohm/contrib'

class Post < Ohm::Model
  include Ohm::Timestamping
  include Ohm::ToHash
  include Ohm::Boundaries
  include Ohm::WebValidations
  include Ohm::NumberValidations

  attribute :amount
  attribute :url
  attribute :poster_email
  attribute :slug

  def validate
    # from NumberValidations
    assert_decimal :amount

    # or if you want it to be optional
    assert_decimal :amount unless amount.to_s.empty?

    # from WebValidations
    assert_slug  :slug
    assert_url   :url
    assert_email :poster_email
  end
end

Post.first
Post.last
Post.new.to_hash
Post.create.to_hash
Post.create.created_at
Post.create.updated_at

# Casting example
class Product
  include Ohm::Typecast

  attribute :price, Decimal
  attribute :start_of_sale, Time
  attribute :end_of_sale, Time
  attribute :priority, Integer
  attribute :rating, Float
end

Typecasting explained

I studied various typecasting behaviors implemented by a few ORMs in Ruby.

ActiveRecord

class Post < ActiveRecord::Base
  # say we have an integer column in the DB named votes
end
Post.new(:votes => "FooBar").votes == 0
# => true

DataMapper

class Post
  include DataMapper::Resource

  property :id, Serial
  property :votes, Integer
end

post = Post.new(:votes => "FooBar")
post.votes == "FooBar"
# => true

post.save
post.reload

# Get ready!!!!
post.votes == 0
# => true

Ohm::Typecast approach.

Mindset:

  1. Explosion everytime is too cumbersome.
  2. Mutation of data is less than ideal (Also similar to MySQL silently allowing you to store more than 255 chars in a VARCHAR and then truncating that data. Yes I know you can configure it to be noisy but the defaults kill).
  3. We just want to operate on it like it should!

Short Demo:

class Post < Ohm::Model
  include Ohm::Typecast
  attribute :votes
end

post = Post.new(:votes => "FooBar")
post.votes == "FooBar"
# => true

post.save
post = Post[post.id]
post.votes == "FooBar"
# => true

# Here comes the cool part...
post.votes * 1
# => ArgumentError: invalid value for Integer: "FooBar"

post.votes = 50
post.votes * 2 == 100
# => true

post.votes.class == Ohm::Types::Integer
# => true
post.votes.inspect == "50"
# => true

More examples just to show the normal case.

require 'ohm'
require 'ohm/contrib'

class Post < Ohm::Model
  include Ohm::Typecast

  attribute :price, Decimal
  attribute :available_at, Time
  attribute :stock, Integer
  attribute :address, Hash
  attribute :tags, Array
end

post = Post.create(:price => "10.20", :stock => "100",
                   :address => { "city" => "Boston", "country" => "US" },
                   :tags => ["redis", "ohm", "typecast"])

post.price.to_s == "10.20"
# => true

post.price * 2 == 20.40
# => true

post.stock / 10 == 10
# => true

post.address["city"] == "Boston"
post.tags.map { |tag| tag.upcase }

# of course mutation works for both cases
post.price += 5
post.stock -= 1
post.tags << "contrib"
post.address["state"] = "MA"
post.save
post = Post[post.id]

post.address["state"] == "MA"
# => true
post.tags.include?("contrib")
# => true

Credits

Thanks to github user gnrfan for the web validations.

Note on Patches/Pull Requests

  • Fork the project.
  • Make your feature addition or bug fix.
  • Add tests for it. This is important so I don't break it in a future version unintentionally.
  • Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
  • Send me a pull request. Bonus points for topic branches.

Copyright

Copyright (c) 2010 Cyril David. See LICENSE for details.

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