ActiveRecordLite

ActiveRecordLite is an object-relational mapping system inspired by ActiveRecord. Uses Ruby's metaprogramming capabilities to implement its core functionality.

Current Features

• SQLObject::find(id) returns a SQLObject with attributes matching the database row having the corresponding id
• SQLObject#insert creates new row in the database with the SQLObject's attributes and assigns an id
• SQLObject#update maps current attribute values over previous column values in the database on the row with the corresponding id
• SQLObject#save inserts or updates SQLObject based on id.nil?
• SQLObject#where(params) forms and executes SQL query based on params; returns an array of SQLObjects
• SQLObject#belongs_to(name, options) defines a method, name, that returns a SQLObject whose #model_name and :primary_key value correspond to the :class_name option and :foreign_key value of the association
• SQLObject#has_many(name, options) is the inverse of #belongs_to; defines a method, name that returns an array of SQLObjects with appropriate #model_names and :primary_key values
• SQLObject#has_one_through(name, through_name, source_name) defines a relationship between two SQLObjects through two #belongs_to relationships. Defines a method, name, that returns a SQLObject whose #model_name corresponds to the source_name

Using ActiveRecordLite

• Add this repo to your project
• Require 'active_record_lite'

Example:

require './ActiveRecordLite/active_record_lite'
DBConnection.open('trees.db')

class Tree < SQLObject
  belongs_to :family
  has_one_through :type, :family, :type

  finalize!
end

class Family < SQLObject
  has_many :trees
  belongs_to :type

  finalize!
end

class Type < SQLObject
  has_many :families

  finalize!
end

type = Type.new(name: "Confier")
type.save

family = Family.new(name: "Cypress", type_id: type.id)
family.save

tree = Tree.new(name: "Dawn Redwood", family_id: family.id)
tree.save

Tree.where(name: "Dawn Redwood") # => [#<Tree:0x007ffc642ec080 @attributes={:id=>1, :name=>"Dawn Redwood", :family_id=>1}>]
Tree.where(name: "Dawn Redwood").first.family # => #<Family:0x007ffc641ff140 @attributes={:id=>1, :name=>"Cypress", :type_id=>1}>
Tree.where(name: "Dawn Redwood").first.type # => #<Type:0x007ffc64088fa0 @attributes={:id=>1, :name=>"Confier"}>

To Do

• Write has_many_through
• Write includes to prefetch data
• Write joins