DynamicRecord

DynamicRecord is a lightweight Ruby object relational mapping (ORM) library. It was built using meta-programming techniques as well as the ActiveSupport::Inflector library. The ORM allows you to seamlessly perform database operations without writing SQL code.

DynamicRecord establishes and relies upon naming conventions to create associations between database tables.

Features and Implementation

The ORM provides users with various methods to facilitate database interaction, including:

• ::all
• ::find
• ::where
• #save (intelligently determines whether to insert a new entry or update an existing one)

When inserting a new record into the database, DynamicRecord ensures that the record's id is not manually generated.

def insert
  cols = self.class.columns.drop(1).map(&:to_s)
  col_names = cols.join(", ")
  question_marks = (["?"] * (cols.count)).join(", ")

  DBConnection.execute(<<-SQL, *attribute_values.drop(1))
  INSERT INTO
    #{self.class.table_name} (#{col_names})
  VALUES
    (#{question_marks})
  SQL

  self.id = DBConnection.last_insert_row_id
end

In addition, it supports the following associations:

• belongs_to
• has_many
• has_one_through

The has_one_through association was carefully crafted to ensure that both source and through classes are defined at the time of method invocation.

def has_one_through(name, through_name, source_name)
  define_method(name) do
    # Note: through_options and source_options variables are declared
    # within the method definition
    through_options = self.class.assoc_options[through_name]
    source_options = through_options.model_class.assoc_options[source_name]

    query_results = self.class.has_one_through_query(self, through_options, source_options)
    source_options.model_class.parse_all(query_results).first
  end
end

Try It Out!

1. Clone this repository and cd to it.
2. Run bundle install.
3. Load a demo:
   • Run bundle exec ruby cookbooks_demo.rb.
   • Run bundle exec ruby universities_demo.rb.
   • Create your own! Follow the example given by universities_demo.rb. You'll need to create a .sql file and a .rb file.
4. To avoid printing queries, pass PRINT_QUERIES=false to the demo command, e.g., PRINT_QUERIES=false bundle exec ruby cookbooks_demo.rb
5. Query the demo database as you please. Any changes made during the demo will not persist, as every demo starts with a fresh database. The cookbooks demo database schema and association details are available below:

Cookbook Database Schema

cookbooks

column name
id (primary key)
title

recipes

column name
id (primary key)
name
cookbook_id (foreign key)

ingredients

column name
id (primary key)
name
recipe_id (foreign key)

Cookbook Database Associations

• Cookbook has many recipes
• Recipe has many ingredients
• Recipe belongs to cookbook
• Ingredient belongs to recipe
• Ingredient has one cookbook through recipe