= Property sets

This gem is a way for you to use a basic "key/value" store for storing attributes for a given model in a relational fashion where there's a row per attribute. Alternatively you'd need to add a new column per attribute to your main table, or serialize the attributes and their values.

== Description

You configure the allowed stored properties by specifying these in the model:

  class Account < ActiveRecord::Base
    property_set :settings do
      property :version, :default => "v1.0"
      property :featured, :protected => true
      property :activated
    end

    property_set :texts do
      property :epilogue
    end
  end

The declared properties can then be accessed runtime via the defined association:

  # Return the value of the version record for this account, or the default value if not set
  account.settings.version

  # Update the version record with given value
  account.settings.version = "v1.1"

  # Query the truth value of the property
  account.settings.featured?

  # Short hand for setting one or more values
  account.settings.set(:version => "v1.2", :activated => true)

=== Validations

Property sets supports standard AR validations, although in a somewhat manual fashion.

  class Account < ActiveRecord::Base
    property_set :settings do
      property :version, :default => "v1.0"
      property :featured, :protected => true

      validates_format_of :value, :with => /v\d+\.\d+/, :message => "of version is invalid",
                          :if => Proc.new { |r| r.name.to_sym == :version }
    end
  end

On +account.save+ this will result in an error record being added. You can also inspect the
setting record using +account.settings.version_record+

=== Bulk operations

Stored properties can also be updated with the update_attributes and update_attributes! methods by
enabling nested attributes. Like this (from the test cases):

  @account.texts_attributes = [
    { :name => "foo", :value => "1"  },
    { :name => "bar", :value => "0"  }
  ]

And for existing records:

  @account.update_attributes!(:texts_attributes => [
    { :id => @account.texts.foo.id, :name => "foo", :value => "0"  },
    { :id => @account.texts.bar.id, :name => "bar", :value => "1" }
  ])

Using nested attributes is subject to implementing your own security measures for mass update assignments.
Alternatively, it is possible to use a custom hash structure:

  params = {
    :settings => { :version => "v4.0", :featured => "1" },
    :texts    => { :epilogue => "Wibble wobble" }
  }
  @account.update_attributes(params)

The above will not update +featured+ as this has the protected flag set and is hence protected from
mass updates.

=== View helpers

We support a couple of convenience mechanisms for building forms and putting the values into the above hash structure. So far, only support check boxes and radio buttons:

  <% form_for(:account, :html => { :method => :put }) do |f| %>
    <h3><%= f.property_set(:settings).check_box :activated %> Activated?</h3>
    <h3><%= f.property_set(:settings).radio_button :hot, "yes" %> Hot</h3>
    <h3><%= f.property_set(:settings).radio_button :not, "no" %> Not</h3>
  <% end %>

== Installation

Install the gem in your rails project by putting it in your Gemfile:

  gem "property_sets"

Also remember to create the storage table(s), if for example you are going to be using this with an accounts model and a "settings" property set, you can define the table like:

  create_table :account_settings do |t|
    t.integer  :account_id, :null => false
    t.string   :name, :null => false
    t.string   :value
    t.timestamps
  end

  add_index :account_settings, [ :account_id, :name ], :unique => true

== Requirements

* ActiveRecord
* ActiveSupport

== LICENSE:

(The MIT License)

Copyright (c) 2011 Zendesk

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.