Question

I need to create a database for managing teams. The 2 tables im wrestling with are the meet table and the events table.

Here is the basic flow

Team A can create a new track meet which will add 1 row to the meet table with meta data for the meet such as dates, location it also has to include a list of events.

Events is a table of about 500 possible events that can be competed at during a meet. Things such as distance, type of event, male / female, age

I want during the generation of a meet for the user to be able to select which events that meet will have.

So create a new meet, complete meta data, and select (for Ex) 30 events from a list of all possible events.

Soooo my question is what table structure best supports that. I was thinking of a column in my meet table that holds and array of events.? But is there a better way to handle that.? Im using postgres and rails

Answer 1

This sounds like a perfect use for the Rails has_many :through association. You should have a meet_events join table. The meet_events table would have a foreign key (belongs_to) meet_id column in it which points to the meet it is associated with and an event_id column in it which points to one of the available events. Your Meet model would use has_many :meet_events and has_many :events, :through => :meet_events. That will allow you to get the event objects associated with this meet.

The MeetEvent model simply has two belongs_to. One for the meet and one for the event.

Here’s a simple set of models:

class Meet < ActiveRecord::Base
  has_many :meet_events
  has_many :events, :through => :meet_events
end

class Event < ActiveRecord::Base
  has_many :meet_events
  has_many :meets, :through => :meet_events
end

class MeetEvent < ActiveRecord::Base
  belongs_to :meet
  belongs_to :event
end

Here’s an example of some data and what it is modeling:

meets

id  |  name
------------------
1   |  Meet 1
2   |  Meet 2

events

id  |  name
------------------
1   |  Event 1
2   |  Event 2
3   |  Event 3

meet_events

id  |  meet_id  |  event_id
----------------------------
1   |  1        |  1
2   |  1        |  3
3   |  2        |  2
4   |  2        |  3

This is basically modeling that Meet 1 has Event 1 and Event 3 in it. Meet 2 has Event 2 and Event 3. This also gives you the benefit of asking a particular Event what meets it is in. So for example, calling event.meets when event is Event 3, it will tell you that both Meet 1 and Meet 2 have that event in them.