Tableless Model

This is an extended Hash that has a defined collection of method-like attributes, and only these attributes can be set or read from the hash. Optionally, you can also set default values and enforce data types for these attributes.

Tableless Model behaves in a similar way to normal ActiveRecord models in that it also supports validations and can be useful, for example, to reduce database complexity in some cases, by removing associations and therefore tables.

In particular, by using Tableless Model, you could save tables whenever you have one to one associations between a parent model and a child model containing options, settings, debugging information or any other collection of attributes that belongs uniquely to a single parent object.

Removing database tables also means reducing the number of queries to fetch associations, therefore it can also help a little bit with performance.

Installation

Tableless Model is available as a Rubygem:

gem install tableless_model

(current version: 0.0.6)

Usage

For example’s sake, say we have these two models:

1)

class Page < ActiveRecord::Base

# having columns such as id, title, etc has_one :seo_options end

2)

class SeoOptions < ActiveRecord::Base

set_table_name “seo_options”

# having columns such as id, title_tag, meta_description, meta_keywords, # noindex, nofollow, noarchive, page_id

belongs_to :page

end

So that each instance of Page has its own SEO options, and these options/settings only belong to a page, so we have a one to one association, and our database will have the tables “pages”, and “seo_options”.

Using Tableless Model, we could remove the association and the table seo_options altogether, by storing those options in a column of the pages table, in a YAML-serialized form. So the models become:

1)

class Page < ActiveRecord::Base

# having columns such as id, title, seo, etc

has_tableless :seo => SeoOptions end

2)

class SeoOptions < ActiveRecord::TablelessModel

attribute :title_tag, :type => :string, :default => “default title tag” attribute :meta_description, :type => :string, :default => “”

attribute :meta_keywords, :type => :string, :default => “”

attribute :noindex, :type => :boolean, :default => false attribute :nofollow, :type => :boolean, :default => false attribute :noarchive, :type => :boolean, :default => false

end

That’s it.

When you now create an instance of SeoOptions, you can get and set its attributes as you would do with a normal model:

seo_options = SeoOptions.new => <#SeoOptions meta_description=“” meta_keywords=“” noarchive=false nofollow=false noindex=false title_tag=“default title tag”>

seo_options.title_tag => “default title tag”

seo_options.title_tag = “new title tag” => “new title tag” Note that inspect shows the properties of the Tableless Model in the same way it does for ActiveRecord models. Of course, you can also override the default values for the attributes when creating a new instance:

seo_options = SeoOptions.new( :title_tag => “a different title tag” ) => <#SeoOptions meta_description=“” meta_keywords=“” noarchive=false nofollow=false noindex=false title_tag=“a different title tag”>

Now, if you have used the has_tabless macro in the parent class, Page, each instance of Page will store directly its YAML-serialized SEO settings in the column named “seo”.

page = Page.new page.seo => <#SeoOptions meta_description=“” meta_keywords=“” noarchive=false nofollow=false noindex=false title_tag=“default title tag”>

page.seo.title_tag = “changed title tag” => <#SeoOptions meta_description=“” meta_keywords=“” noarchive=false nofollow=false noindex=false title_tag=“changed title tag”>

And this is how the content of the serialized column would look like in the database if you saved the changes as in the example

— !map:SeoOptions noarchive: false meta_description: meta_keywords: nofollow: false title_tag: “changed title tag” noindex: false

Validations

Tableless Model uses the Validatable gem to support validations methods and callbacks (such as “after_validation”). Note: it currently uses the Rails 2.x syntax only.

Example:

class SeoOptions < ActiveRecord::TablelessModel

attribute :title_tag, :type => :string, :default => “” attribute :meta_description, :type => :string, :default => “”

attribute :meta_keywords, :type => :string, :default => “”

attribute :noindex, :type => :boolean, :default => false attribute :nofollow, :type => :boolean, :default => false attribute :noarchive, :type => :boolean, :default => false

validates_presence_of :meta_keywords end

Testing:

x = SeoOptionsSettings.new => <#SeoOptions meta_description=“” meta_keywords=“” noarchive=false nofollow=false noindex=false title_tag=“”>

x.valid? => false x.meta_keywords = “test” => “test” x.valid? => true

TODO

  • Support for associations

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