has_generic_list

is a plugin to store lists of data associated with a model without having to create lots of tables, one for each type of data.

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Email address: [email protected]

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Installation

ruby script/plugin install git://github.com/damianham/has_generic_list.git

or add to the Gemfile with

gem 'has_generic_list', :git => 'git://github.com/damianham/has_generic_list.git'

Prepare database

Generate and apply the migration:

ruby script/generate has_generic_list_migration rake db:migrate

Basic usage

Let's suppose you have a Company model and you want to store lists of data associated with each Company e.g

• countries of operation
• languages spoken
• product names...... etc. etc. you get the idea

i.e lists of any kind of data. You could also serialize an object and store that as the list item value as long as the serialized data length is less than the item_value column length in the generic_list_items table. If you want to store larger data then change the item_value column to a text column.

The first step is to add has_generic_list to the Company class:

class Company < ActiveRecord::Base
	  # the type names MUST be singular, if typename == typename.pluralize then an exception is raised
	  has_generic_list :types => [:country,:language,:office,:person] # as many types as you need
end

We can now use the pluralized methods generated by has_generic_list for each data type which work like regular array attribute accessors.

c = Company.find(:first)

c.countries # [] c.countries = ["UK", "US","CA"]

c.languages # [] c.languages = ["English", "French","Spanish"]

c.countries # ["UK", "US","CA"] c.languages # ["English", "French","Spanish"]

To display the value as a String use to_s, i.e.

c.languages[0].to_s # "English"

You can get all elements of the list as a comma separated String with to_s on the list itself, i.e

c.languages.to_s # "English, French, Spanish"

You can also add or remove elements of data.

c.languages.add("German", "Dutch") c.languages.remove("French")

You can do the normal array traversal on the list but you have to use the add/remove methods to modify the list.

Finding objects by the generic list data

To retrieve objects that have a particular list entry use _find_with_list, i.e

companies = Company.languages_find_with_item('Spanish')

which is just a convenience method for

Company.find_with_generic_list_item(:language,'Spanish') # note the singular type name

and to just get the object identifiers use

company_ids = Company.languages_find_ids_with_item('Spanish')

which returns an array of ids

Other

Problems, comments, and suggestions all welcome [email protected]