patientslikeme / migration_helpers

I found the following modification to add_foreign_key very useful:

def add_foreign_key(table, column, target_table, options = {})

    o = {
      :target_column => "id",
      :constraint_name => "#{table.to_s}_#{target_table.to_s}_fkey",
      :on_delete => nil
    }.merge(options)

    delete_action = "NO ACTION"
    if o[:on_delete] == :restrict
      delete_action = "RESTRICT"
    elsif o[:on_delete] == :cascade
      delete_action = "CASCADE"
    else
      raise "unexpected value for :on_delete! permitted: nil, :restrict, :cascade"
    end
    execute "ALTER TABLE #{table.to_s} ADD CONSTRAINT #{o[:constraint_name].to_s} FOREIGN KEY (#{column.to_s}) REFERENCES #{target_table.to_s} (#{o[:target_column].to_s}) ON DELETE #{delete_action};"
  end