JKDB

Summary

JKDB is an ORM library modeled on ActiveRecord from Ruby on Rails that provides a convenient interface to interact with databases in SQLite.

Features

Create and Update Rows

Users can create and insert new records for tables in their database or update existing records.

def initialize(params = {})
  params.each do |col, val|
    col_sym = col.to_sym

    raise "unknown attribute '#{col_sym}'" unless
      self.class.columns.include?(col_sym)

    self.send("#{col_sym}=", val)
  end
end

def insert
  cols = self.class.columns.drop(1)
  cols_str = cols.map { |col| col.to_s }.join(", ")

  marks = []
  cols.length.times { |n| marks << "?" }
  marks = marks.join(", ")

  row = DBConnection.execute(<<-SQL, *self.attribute_values.drop(1))
    INSERT INTO
      #{self.class.table_name} (#{cols_str})
    VALUES
      (#{marks})
  SQL

  self.id = DBConnection.last_insert_row_id
end

Searching

Users can search for specific records in the database by id using the .find(id) method, or by specific column values using .where(params) and providing a hash of the desired parameters.

def where(params)
  cols = params.keys.map { |col| "#{col} = ?" }.join(" AND ")
  vals = params.values
  
  records = DBConnection.execute(<<-SQL, *vals)
    SELECT
      *
    FROM
      #{self.table_name}
    WHERE
      #{cols}
  SQL

  self.parse_all(records)
end

Associations

JKDB allows users to define the belongs_to, has_many, and has_one_through associations of their relational database in their class definitions. For the first two associations, users must provide the name of the foreign key but default values are provided for the primary keys and class names if table names are standardized. Otherwise, users can provide a hash to define the primary key and class name for the association.

class Fighter < SQLObject
  attr_accessor :id, :name, :ranking, :division_id

  belongs_to :division
  has_one_through :promotion, :division, :promotion

  finalize!
end

class BelongsToOptions < AssocOptions
  def initialize(other_class_name, options = {})
    belongs = {
      foreign_key: "#{other_class_name}_id".to_sym,
      primary_key: :id,
      class_name: other_class_name.to_s.singularize.camelcase
    }

    belongs.keys.each do |assoc|
      self.send("#{assoc}=", options[assoc] || belongs[assoc])
    end
  end
end

Using the Demo

Clone this repo
cd JKDB/
bundle install
sqlite3 'mma.db' < 'mma.sql'
Load pry or irb
Run load 'jkdb.rb'
Experiment with the methods below!

Defined Methods

Database

DBConnection.open(db_file)
DBConnection.instance

Tables

::columns
::all
::find(id)
::where(search_params)
::table_name=

Records

#attributes
#attribute_values
#{attribute}
#{attribute}=
#save

jkim421/JKDB