Question

I have a category model

   default_scope :order => 'display_order asc'
   has_many :resources, :dependent => :destroy

# == Schema Information
#
# Table name: categories
#
#  id          :integer(4)      not null, primary key
#  name        :string(255)
#  description :string(255)
#  created_at  :datetime        not null
#  updated_at  :datetime        not null
#

I have a resources model:

belongs_to :category
  # belongs_to :submitter, :class_name => 'User', :foreign_key => "submitter_id"
  has_and_belongs_to_many :filetypes
  has_many :users, :through => :kits
  has_many :kits
  belongs_to :submitter, class_name: "User"
  belongs_to :author

== Schema Information

#
# Table name: resources
#
#  id                 :integer         not null, primary key
#  title              :string(255)
#  url                :string(255)
#  description        :string(255)
#  price              :decimal(, )
#  created_at         :datetime        not null
#  updated_at         :datetime        not null
#  category_id        :integer
#  image_file_name    :string(255)
#  image_content_type :string(255)
#  image_file_size    :integer
#  image_updated_at   :datetime
#  status             :string(255)
#  submitter_id       :integer
#  author_id          :integer
#

The client wants to be able to create categories but assign different attributes to the resource depending on the category.

Example:
category created: ‘Books’
He would like to have fields ‘author’ for example stored in the Resource model.

category created: ‘Conference’
He would like to have fields ‘location’, ‘date’ for example stored in the Resource model.

How can I model this so its dynamic and easy to maintain in the long term?

Answer 1

One idea would be to have a separate table just for the fields of a category. For example, your setup could look something like this:

category HABTM category_fields
category_field HABTM categories
category_field has_many category_field_values
category_field_value belongs_to category_field

Then, when your client created a new category, i.e. Books, he could add a new category_field to that category called author. Then if he wanted to add a new author to the Books category, he would add a category_field_value (i.e. JK Rowling) to the author category_field.

Thus,
the Books category would have an author category_field, and the author category_field would have one category_field_value (JK Rowling).