Record-Conjurer

Record-Conjurer is an object-relational mapper inspired by Ruby on Rails' Active Record. This ORM allows Ruby classes to connect to SQLite3 relational database tables. A sample database is provided for experimentation in Pry.

Setup
Usage
Things to Try
Demo Classes
Sample Database Schema
Future Implementations

Setup (for sample DB)

Clone the repo
Run bundle install in the root directory
Run bundle exec pry in the root directory
Have fun poking about!

Usage

All classes inherit from RecordConjurer, thus will have the following interfaces

::all returns all of the records in the associated table as an array
::table_name returns the name of the table use in the db
::new(field_hash) will create a new instance and will set fields to value provided in the optional hash
::find(id) returns a record with that id, or nil if not found
#save will add a new record to the db with the values provided. Returns the new id.
#field_name returns the value of the field for that record
#field_name= sets the value of the field for that record
#update saves that changes made to a record
#attributes returns a hash with field:value pairs
#attribute_values returns an array of all the values

Things to Try

  Artist.all #=> Array of artists
  Track.all #=> Array of tracks
  accept_band = Artist.find(2) #=> #<Artist:0x007fcbc01d7e80 @attributes={:id=>2, :Name=>"Accept"}>
  accept_band.albums #=> Array of albums belonging to accept_band
  aerosmith = Artist.where(name: "Aerosmith").first #=> #<Artist:0x007fcbbfaa5c20
                                                    #      @attributes={:id=>3, :Name=>"Aerosmith"}>
  aerosmith_album = aerosmith.albums.first  #=> #<Album:0x007fcbc11a5768
                                            #     @attributes={
                                            #       :id=>5,
                                            #       :Title=>"Big Ones",
                                            #       :ArtistId=>3}>
  aerosmith_album.tracks #=> Array of tracks
  song_where = {name: "Dude (Looks Like A Lady)"}
  song = Track.where(song_where).first  #=> #<Track:0x007fcbc144b210
                                        #      @attributes=
                                        #       {:id=>27,
                                        #        :Name=>"Dude (Looks Like A Lady)",
                                        #        :AlbumId=>5,
                                        #        :MediaTypeId=>1,
                                        #        :GenreId=>1,
                                        #        :Composer=>"Steven Tyler, Joe Perry, Desmond Child",
                                        #        :Milliseconds=>264855,
                                        #        :Bytes=>8679940,
                                        #        :UnitPrice=>0.99}>
  song.artist #=> #<Artist:0x007fcbc02c7f98 @attributes={:id=>3, :Name=>"Aerosmith"}>
  aerosmith.Name = 'not aerosmith' #=> "not aerosmith"
  aerosmith.update #=> 0
  Artist.find(3) #=> #<Artist:0x007f921bbae2d0 @attributes={:id=>3, :Name=>"not aerosmith"}>
  new_artist = Artist.new(Name: 'Sonic') #=> #<Artist:0x007f921bb3d5d0 @attributes={:Name=>"Sonic"}>
  new_artist.save #=> 276
  Artist.all.last #=> #<Artist:0x007f921b94f840 @attributes={:id=>276, :Name=>"Sonic"}>

Demo Classes

These are set up in demo.rb and autoloaded via .pryrc when pry is ran

Albums
Artists
Generes
MediaTypes
Playlists
PlaylistTracks
Tracks

Sample Database Schema

Database is a subset of the chinook database

`Albums`

column name	data type	details
`id`	integer	not null, primary key
`Title`	nvarchar(160)	not null
`ArtistId`	integer	not null, foreign key

index on ArtistId
ArtistID references Artists

`Artists`

column name	data type	details
`id`	integer	not null, primary key
`Name`	nvarchar(120)	not null, indexed, unique

`Genres`

column name	data type	details
`id`	integer	not null, primary key
`Name`	nvarchar(120)

`media_types`

column name	data type	details
`id`	integer	not null, primary key
`Name`	nvarchar(120)

`Playlists`

column name	data type	details
`id`	integer	not null, primary key
`Name`	nvarchar(120)

`playlist_tracks`

column name	data type	details
`PlayListId`	integer	not null, foreign key, primary key
`TrackId`	integer	not null, foreign key

index on [:PlayListId, :TrackId], unique: true
PlayListId references Playlists
TrackId references Tracks

`Tracks`

column name	data type	details
`id`	integer	not null, primary key
`name`	nvarchar(200)	not null, indexed, unique
`AlbumId`	integer	foreign key
`MediaTypeId`	integer	not null, foreign key
`GenreId`	integer	foreign key
`Composer`	nvarchar(220)
`Milliseconds`	integer	not null
`Bytes`	integer
`UnitPrice`	numeric(10,2)	not null

AlbumId references Albums
MediaTypeId references MediaTypes
GenreId references Genres

Future Implementations

Forthcoming features include:

The ability to select specific fields vs *
The ability to include relations to prevent n+1 queries
The abiltity to represetn has_many_through relations
The ability to see the generated SQL statements

mafeg95 / record-conjurer