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Acts As Bytefield :: ActiveRecord Bytefield Plugin

Posted by admin Tue, 24 Apr 2007 02:58:00 GMT

We needed a convenient way to store a series of values in a single field. A bitfield would not do because it would only allow a value of 1 or 0 for each field, and we wanted to be able to store at least 3 values for each field.

So I found Gabriel Gironda’s acts_as_bitfield plugin and made a few tweaks. ActsAsBytefield is the result. It allows storage of 256 values in each field, or 255 discrete values ranging from 0-255 (unsigned char or byte) for each value in a MySQL varchar(255) field.

NOTE: Gabriel’s site has been down for some time. My own repository has also been down but is now back up. Sorry for the inconvenience.

Values greater than 255, or less than 0 wrap around. For example, setting a bytefield column to -1 will actually set it to 255, and setting it to -2 will actually set it to 254, etc.

Installation

./script/plugin install acts_as_bytefield

./script/plugin install https://svn.cbciweb.com/svn/plugins/acts_as_bytefield

Documentation (RDoc)

rake rdoc

Testing

The tests require rspec

rake test

Usage

• Create a string column in your table – varchar(255)
• Add this directive to your model:

 acts_as_bytefield :bytefield_column_name, :fields => [:field_name_one, :field_name_two]

You will then be able to use the model in the following manner, for example:

 class SomeModel < ActiveRecord::Base
   acts_as_bytefield :bfield, :fields => [:test, :production]
 end

 obj = SomeModel.new(:test => 1)

 obj.test          #=> 1
 obj.test?         #=> 1
 obj.production?   #=> 0

 obj.test = 0
 obj.production = 65
 obj.save

 obj.test?         #=> 0
 obj.production?   #=> 65

 # The field that's storing the value:
 obj.bfield        #=> "\000A"