ORMery is an object-relational mapping tool built using Ruby, with an SQLite3 database.

To try it out, simply load songs.rb into your favorite Ruby REPL (we recommend pry but irb works just fine).

To use your own SQL file, add it to db_connection.rb by changing the SQL_FILE function like so:

SQL_FILE = File.join(ROOT_FOLDER, 'YOUR_FILE.sql')
DB_FILE = File.join(ROOT_FOLDER, 'YOUR_DB.db')

In the terminal, run the following command to create the database:

cat YOUR_FILE.sql | sqlite3 YOUR_DB.db

Your SQL database is now ready to go!

To create your own classes, create a .rb file, and add require_relative 'lib/sql_object'.

Each class needs to inherit from SQLObject. After writing any associations, you must also include the finalize! method for any changes to take effect.

Look at song.rb for reference!

Song.all #Returns all songs

Album.find(1) #Finds the album where id = 1
Album.columns #Returns an array of all the columns in the table

Artist.table_name #Returns the name of its SQL table
Artist.table_name = #Change the name of SQL table

Class instances can be created, modified, and saved easily:

charlie_parker = Artist.new(name: "Charlie Parker") #.new takes in an optional params hash
charlie_parker.save

bud_powell = Artist.new
bud_powell.name = "Bud Powell"
bud_powell.save

To search by a specific column value, use the .where method, passing in a hash with the column as a key and the query as the value:

Artist.where(name: "John Coltrane") #Returns either an artist object or an empty array if nothing is found

Write your associations in the class definition, before calling finalize!:

class Song < SQLObject
  belongs_to :album #First association
  has_one_through :artist, :album, :artist #Second association
  finalize!
end

ORMery currently supports three different associations:

• belongs_to - Use when a class has a foreign_id column pointing to another class's primary_id column. Takes a required name, and an optional hash for class_name, primary_key, foreign_key.

• has_many - The opposite of belongs_to. Use when another class has a column pointing to its own primary_id. Takes a required name, and an optional hash for class_name, primary_key, foreign_key.

• has_one_through - Connects two belongs_to associations. Requires three arguments: name, through_name, and source_name.

In our demo file, Songs belong to Albums, Albums belong to Artists, and Songs have one Artist through Albums.

We can then call these associations as methods:

Song.album
Song.artist

Album.songs

Artist.albums

Here are some features I intend to incorporate in future releases:

• .first and .last methods
• .join
• has_many_through and belongs_to_through associations