Ruby on Rails Relationships for Two Models

Question

I have two different models.

Item Model

class Item < ActiveRecord::Base
    belongs_to :category
    attr_accessible :make, :model, :name, :purchasedfrom, :qrcode, :serialnumber, :category_id
end

Event Model

class Event < ActiveRecord::Base
    belongs_to :category
    attr_accessible :name, :location_id, :category_id
end

I cannot figure out how to do the following:

An Event has multiple Item that can be at the Event.
An Event history still shows Items from a particular event.
Would show items from event: localhost/event/:id/items

I cannot figure out this for the life of me. If I can get some direction in this issue, I would greatly appreciate it! Thanks in advance for all of your help.

I have seen the use of :through which I believe I would have to use here.

You should either use `has many :through` or `has_and_belongs_to_many` relation. — samuil, Nov 23 '12 at 14:30

score 1 · Answer 1 · answered Nov 23 '12 at 14:56

1

If I understood your question correctly, here you can write something like this in Event model.

class Event
  def items
    category.items
  end
end

then in controller,

@event = Event.find(params[:id])
@items = @event.try(:items)

answered Nov 23 '12 at 14:56

Santosh

1,251
9
15

Make sure to double to check to see if the `category` association exists before calling the `items` attribute. – matsko Nov 23 '12 at 15:04

244an · Answer 2 · 2012-11-23T15:25:29.260

0

If one Category can have many Events I think you must add event_id in Item to be able to know exactly what Items that has been on exactly one Event. (And in that case add relations for that).

Or join table between Event and Item and has_and_belongs_to_many if one Item can be on many Events

EDIT:

If it's like that, add table events_items, relation has_and_belongs_to_many :items (in Event and :events in Item), and read documentation for has_and_belongs_to_many.

Otherwise, if you are looking for Items that has been on a certain Event you will find all Items that have been on all Events that has the same Category as the Event you are investigating.

edited Nov 23 '12 at 15:25

answered Nov 23 '12 at 15:04

244an

1,579
11
15

I am really confused. An `Item` can be at an `Event`. An `Item` is like a speaker or microphone used at said `Event`. So we have multiple `Item` at an `Event`. The `Event` is over and the items return back to where they are stored. However, if I view the event, I can see the items that were apart of that `Event`. The `Event` table has `:name, :location_id, :event_date, :category_id`. So HOW do I associate MULTIPLE `Item` at different `Events`? – Turp Nov 23 '12 at 15:18
I changed in my suggestion, hope that answer your question. – 244an Nov 23 '12 at 15:24

score 0 · Answer 3 · answered Nov 23 '12 at 15:06

0

I think that what you would want to do is:

class Item < ActiveRecord::Base
    belongs_to :event
end

and for Events:

class Event < ActiveRecord::Base
    has_many :items
end

Then you should be able to view the items for an event by calling:

@event = Event.find_by_id(:id)
@event.items.all

answered Nov 23 '12 at 15:06

allareri

173
2
7

1

I am really confused. An `Item` can be at an `Event`. An `Item` is like a speaker or microphone used at said `Event`. So we have multiple `Item` at an `Event`. The `Event` is over and the items return back to where they are stored. However, if I view the event, I can see the items that were apart of that `Event`. The `Event` table has `:name, :location_id, :event_date, :category_id`. So HOW do I associate MULTIPLE `Item` at different `Events`? – Turp Nov 23 '12 at 15:16

Ruby on Rails Relationships for Two Models

3 Answers3