Add two foreign key columns that reference the same table

Questions & Help Questions
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8

I’m not sure exactly what you mean by “on the same line”, but you treat them as two different associations. For example here are some samples:

defmodule Ex338.Waiver do
  schema "waivers" do
    belongs_to :add_fantasy_player, Ex338.FantasyPlayer
    belongs_to :drop_fantasy_player, Ex338.FantasyPlayer
  end
  
  def query(query) do
    from w in query,
      inner_join: a in assoc(w, :add_fantasy_player),
      inner_join: d in assoc(w, :drop_fantasy_player)
  end

  def preload_assocs(query) do
    from w in query,
      preload: [:add_fantasy_player, :drop_fantasy_player]
  end
end

defmodule Ex338.FantasyPlayer do
  schema "fantasy_players" do
    has_many :waiver_adds, Ex338.Waiver, foreign_key: :add_fantasy_player_id
    has_many :waivers_drops, Ex338.Waiver, foreign_key: :drop_fantasy_player_id
  end

  def waiver_adds(query) do
    from f in query,
      inner_join: w in assoc(f, :waiver_adds),
      preload: [:waiver_adds]
  end
end