Multiple nested forms in rails 5

Question

I'm looking into nested attributes and I have a few questions about relationships between models.

Say I have a Show that has_many Seasons. Both Show and Season can have many Actors and Staff. See table example:

When a Show is created, Season accepts the Show association and both Actors and Staff accept both the Show and Season attributes. Would this be a triple nested form?

So my models would look like this?

class Show < ApplicationRecord
  has_many :seasons, dependent: :destroy
  has_many :actors, dependent: :destroy
  has_many :staff, dependent: :destroy

  accepts_nested_attributes_for :seasons, allow_destroy: true
  accepts_nested_attributes_for :actors, allow_destroy: true
  accepts_nested_attributes_for :staff, allow_destroy: true
end

class Season < ApplicationRecord
  belongs_to :show
  has_many :actors, dependent: :destroy
  has_many :staffs, dependent: :destroy

  accepts_nested_attributes_for :actors, allow_destroy: true
  accepts_nested_attributes_for :staff, allow_destroy: true
end

class Actor < ApplicationRecord
  belongs_to :show
  belongs_to :season
end

class Staff < ApplicationRecord
  belongs_to :show
  belongs_to :season
end

And my Show Controller would look like:

class ShowsController < ApplicationController
  def create
   @show.seasons.build
   @show.seasons.build.actors.build
   @show.seasons.build.staffs.build
  end
end

If I understand the problem correctly, when Show is created you also want to create a Season (one) for this Show, and Actors (many) and Staff (many), correct? — Ilya Konyukhov
– Ilya Konyukhov, Commented Oct 20, 2018 at 1:45
Ok, thanks. Your data schema is incorrect then. In code model Actor has many shows and has many seasons. The same for Staff. But above the schema you wrote: Both Show and Season can have many Actors and Staff — Ilya Konyukhov
– Ilya Konyukhov, Commented Oct 20, 2018 at 1:48
Ok. So I have updated my models above. Is this correct? And to build the Actor and Staff nested attributes do I do what's in the Show Controller? — yellowskull
– yellowskull, Commented Oct 20, 2018 at 1:54
Oh, I didn't see your comment and wrote an answer. Yes, now it is correct — Ilya Konyukhov
– Ilya Konyukhov, Commented Oct 20, 2018 at 1:57

Ilya Konyukhov · Accepted Answer · 2018-10-20 02:05:18Z

1

Correct schema is:

class Show < ApplicationRecord
  has_many :seasons, dependent: :destroy
  has_many :actors, dependent: :destroy
  has_many :staff, dependent: :destroy

  accepts_nested_attributes_for :seasons, allow_destroy: true
  accepts_nested_attributes_for :actors, allow_destroy: true
  accepts_nested_attributes_for :staff, allow_destroy: true
end

class Season < ApplicationRecord
  belongs_to :show
end

class Actor < ApplicationRecord
  belongs_to :show
  belongs_to :season
end

class Staff < ApplicationRecord
  belongs_to :show
  belongs_to :season
end

The rule is simple - if table objects has a foreign key subject_id, which links it to table subjects, then model Object may contain belongs_to :subject association.

There is a nice explanation about which relationship to use in your model depending on foreign_key placement.

Off-topic:

I don't know the specifics of your project, but it looks a bit offensive. You create new actors and staff each time a new show is created like they are expendable. I do not want to seem cynical, but the actors and the staff can be reused. If so, it could be reasonable to create has_and_belongs_to_many relationships.

edited Oct 20, 2018 at 2:05

answered Oct 20, 2018 at 1:55

Ilya Konyukhov

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6 Comments

yellowskull Over a year ago

Thanks for the clarification. Appreciate it.

yellowskull Over a year ago

I have another question about these nested forms, similar to this, but with a a trickier outcome if you have the time?

Ilya Konyukhov Over a year ago

Yes, sure, what's the question?

yellowskull Over a year ago

Should I open a new question?

Ilya Konyukhov Over a year ago

No, you can write here. It's more convenient to open a chat, however I cannot find how to do it :(

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