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ruby-on-railshas-many-polymorphs

Rails combine multiple polymorphic has_many associations


I have a model called Organization that has many teams and has many collaborations. A Collaboration also has many teams. So the team model has a polymorphic association with Organization and Collaboration.

What I would like to do is organization.teams and have that reflect all teams from the organization and all teams from the collaborations a part of the organization.

Tables

*organizations*
id
user_id
title
...

*collaborations*
id
organization_id
title
...

*teams*
id
teamable_id
teamable_type
title
...

Models

class Organization < ApplicationRecord

  has_many :orgaization_teams, as: :teamable, class_name: "Team"
  has_many :collaboration_teams, through: :collaborations, source: :teams, class_name: "Team"

end

class Collaboration < ApplicationRecord

  belongs_to :organization
  has_many :teams, as: :teamable

end

class Team < ApplicationRecord

  belongs_to :teamable, polymorphic: true
  belongs_to :organization, -> { joins(:teams).where(teams: {teamable_type: 'Organization'}) }, foreign_key: 'teamable_id'
  belongs_to :collaboration, -> { joins(:teams).where(teams: {teamable_type: 'Collaboration'}) }, foreign_key: 'teamable_id'

end

Attempts

Attempt #1

class Organization < ApplicationRecord

  has_many :teams, -> { joins(:organization, :collaboration) }, source: :teamable

end

Result: SystemStackError (stack level too deep)

Attempt #2

class Organization < ApplicationRecord

  def teams
    orgaization_teams.or(collaboration_teams)
  end

end

Result: ArgumentError (Relation passed to #or must be structurally compatible. Incompatible values: [:joins])

Potential Solution

I'm considering separating the polymorphic association on Team to organization_id and collaboration_id

So the new table would look like this:

*teams*
id
organization_id
collaboration_id
title
...

Solution

  • I would go with two seperate foreign keys instead:

    class Organization < ApplicationRecord
      has_many :teams
      has_many :collaborations
      has_many :collaboration_teams, 
        through: :collaborations,
        source: :team
    end
    
    class Collaboration < ApplicationRecord
      belongs_to :organization
      has_many :teams
    end
    
    class Team < ApplicationRecord
      belongs_to :team, optional: true
      belongs_to :organization, optional: true
    end
    

    If you want to get teams that directly belong to an or org or a its collaborations you want:

    Team.where(
      organization_id: org.id
    ).or(
      Team.where(
        collaboration_id: org.collaborations
      )
    )
    

    I don't think this can actually be written as an association as its too structurally complex.