Sharable content the Rails way


#1

I have a little issue about how to structure a database for a Rails
app that includes sharing.
The application is for song writers and musicians and helps then
collaborate on musical pieces.

Essentially there are a couple of parts

  • There are ‘owners’ who create ‘songbooks’ and ‘songs’.
  • Each ‘songbook’ can contains many ‘songs’ and ‘songs’ must belong
    to
    one ‘songbook’, although they can be copied as new versions to
    other
    ‘songbooks’
  • Both ‘songsbooks’ and ‘songs’ can be shared with other ‘owners’ to
    various degrees.

I can elect to make a ‘songbook’ or ‘song’ shared with other users
in the following ways (I’d need to know their email address or
username):
- read-only (can only read, can’t contribute)
- read-write (can read and edit existing songs but can’t add new
ones)
- read-write-add (can read, edit and contribute new songs to the
songbook - this doesn’t apply to a single shared song, just
songbooks)

I can also make ‘songs’ and ‘songbooks’ public:
- public-read (anyone, even users who aren’t subscribed to the
service or aren’t logged in can read)
- public-full (anyone, even users who aren’t subscribed to the
service or aren’t logged in can read and edit songs - although
they can’t add songs)

Now, I’m a little new to Rails and I know how I’d go about this in C#
(i.e. by writing lots and lots of code) but Rails has so many
mechanisms that I am unaware of I was wondering if there was already
some way or doing this, or if not all of it then maybe 90%
Problem is I’m not sure if I need to structure my tables a certain
way, or if there are fields I need to include, or what. I’m not even
sure where to start. I’ve searched this forum and Google and whole
bunch of places but I now have more questions than answers.

I guess the way I’d do it is something like:

Tables (roughly):

owners
id - integer
email - varchar(255)
username - varchar(20)
password…

songbooks
id - integer
name - varchar(50)
owner_id - integer

songs
id - integer
name - varchar(50)
songbook_id - integer

songbook_shares
owner_id - integer
songbook_id - integer
type - integer

song_shares
owner_id - integer
song_id - integer
type - integer

Models:

class Owner < ActiveRecord::Base

has_many :songbooks
has_many :songbook_shares
has_many :song_shares

etc...

end

class Songbook < ActiveRecord::Base

belongs_to :owner

etc...

end

class Song < ActiveRecord::Base

belongs_to :songbook

etc...

end

But this is where I get stuck. I suspect my original table ideas are
wrong, but I’m just not sure how to proceed in the Rails way.

If anyone has tackled something like this before and could point me in
the right direction I’d really appreciate it.

Dale


#2

I think you want to be looking at has_many :through - also coming form
a C#ish background, it took me a while to get my head round.

Briefly, you have something like:

class Owner
has_many :songbooks
has_many :songs, :through => songbooks
end

class Songbook
has_many :songs
belongs_to :owner
end

class Song
belongs_to :song
belongs_to :songbook
end

This way you can do:
Owner.songs
Owner.songbooks[key].songs
etc.

I’d recommend getting the owner / songbook / song association going
first, then bringing shares into the picture.

hth
hth