https://github.com/shuber/hattr_accessor

Allows you to define attr_accessors that reference members of a hash
https://github.com/shuber/hattr_accessor

Last synced: 11 months ago
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Allows you to define attr_accessors that reference members of a hash

• Host: GitHub
• URL: https://github.com/shuber/hattr_accessor
• Owner: shuber
• License: mit
• Created: 2008-10-14T22:30:28.000Z (over 17 years ago)
• Default Branch: master
• Last Pushed: 2010-01-07T01:49:25.000Z (over 16 years ago)
• Last Synced: 2025-05-16T07:51:49.843Z (about 1 year ago)
• Language: Ruby
• Homepage:
• Size: 109 KB
• Stars: 26
• Watchers: 3
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.markdown
  • Changelog: CHANGELOG
  • License: MIT-LICENSE

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README

          
hattr\_accessor

===============

Allows you to define attr\_accessors that reference members of a hash

Installation

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

	gem install hattr_accessor

Usage

-----

The hattr\_accessor method requires an option named `:attribute` which should be name of an attribute which will store the hash. For example:

	class DataSource

	  hattr_accessor :adapter, :username, :password, :attribute => :credentials

	end

The reader and writer methods for `:attribute` (`:credentials` in the example above) would be automatically created unless they exist already. 

You can then use those attributes like normal ones:

	@data_source = DataSource.new

	@data_source.adapter = 'mysql'

	@data_source.username = 'root'

	@data_source.credentials # { :adapter => 'mysql', :username => 'root' }

	

	@data_source.credentials = {}

	@data_source.adapter # nil

The reader method for `:attribute` is overwritten with logic to ensure that it returns a hash by default.

	@data_source = DataSource.new

	@data_source.credentials # {}

You may optionally pass a `:type` option which will type cast the values when calling their getter methods. This is useful if you're using this 

gem with rails which will pass values as strings if submitted from a form. For example:

	class CustomField::Date < CustomField

	  hattr_accessor :offset, :type => :integer, :attribute => :configuration

	  hattr_accessor :unit, :reference, :type => :string, :attribute => :configuration

	  

	  def default_value

	    self.offset.send(self.unit.to_sym).send(self.reference.to_sym)

	  end

	end

	

	@custom_field = CustomField::Date.new(:offset => '5', :unit => 'days', :reference => 'from_now')

	@custom_field.offset # 5 (notice it's an integer, not a string)

	@custom_field.default_value # evaluates 5.days.from_now 

The current options (email me for suggestions for others) for `:type` are:

	:string

	:integer

	:float

	:boolean

	:decimal

	:array

To specify a default value for a member use the `:default` option. For example:

	class DataSource

	  hattr_accessor :adapter, :default => 'mysql', :attribute => :credentials

	  hattr_accessor :username, :default => 'root', :attribute => :credentials

	  hattr_accessor :password, :attribute => :credentials

	end

	

	@data_source = DataSource.new

	@data_source.adapter # 'mysql'

You can also specify a proc for the default value. For example:

	class DataSource

	  hattr_accessor :adapter, :default => 'mysql', :attribute => :credentials

	  hattr_accessor :username, :attribute => :credentials,

	                 :default => lambda { |datasource| Etc.getpwuid(Process.uid).name }

	  hattr_accessor :password, :attribute => :credentials

	end

	

	@data_source = DataSource.new

	@data_source.username # 'process_username'

If you want to take advantage of type casting but also want to return `nil` if a value has not been set then use the `:allow_nil` option. 

By default `:allow_nil` is false for typed members but true for non-typed members. For example:

	class DataSource

	  hattr_accessor :adapter, :type => :string, :allow_nil => true, :attribute => :credentials

	  hattr_accessor :username, :type => :string, :attribute => :credentials

	  hattr_accessor :password, :attribute => :credentials

	end

	

	@data_source = DataSource.new

	@data_source.adapter # nil

	@data_source.username # ''

	@data_source.password # nil

NOTE: Make sure your call `define_attribute_methods` before calling `hattr_accessor` when you're using ActiveRecord and your `:attribute` is a 

database field. The call to `define_attribute_methods` must be after the `serialize` call so that `define_attribute_methods` knows about the 

serialized field.

	class CustomField < ActiveRecord::Base	  

	  serialize :configuration, Hash

	  define_attribute_methods

	  

	  hattr_accessor :testing, :attribute => :configuration

	end

Contact

-------

Problems, comments, and suggestions all welcome: [shuber@huberry.com](mailto:shuber@huberry.com)