Ruby On Rails - Rake task to check for missing foreign keys

check_keys.rake

namespace :db do
  desc "Check for missing foreign keys and generate migration commands"
  task check_keys: :environment do |_task, _args|
    Rails.application.eager_load!
    schema = ApplicationRecord.connection
    missing_foreign_keys = []

    puts ApplicationRecord.descendants
    # Loop through each ActiveRecord model
    ApplicationRecord.descendants.each do |model|
      puts "iterating on #{model}"
      next if model.abstract_class? || !model.table_exists?

      # Check for belongs_to associations
      model.reflect_on_all_associations(:belongs_to).each do |assoc|
        next if assoc.polymorphic?
        puts "checking #{model}.#{assoc.name}"
        foreign_key = assoc.foreign_key
        target_table = assoc.klass.table_name

        # Check if the foreign key exists in the database schema
        foreign_key_exists = schema.foreign_keys(model.table_name).any? { |fk| fk.options[:column] == foreign_key }

        # Check if the column is an integer to suggest a bigint conversion
        column_type = model.columns_hash[foreign_key]&.sql_type

        unless foreign_key_exists
          if column_type == "integer"
            missing_foreign_keys << "  # Change column type to bigint before adding foreign key:\n" \
              "  change_column :#{model.table_name}, :#{foreign_key}, :bigint\n"
          end
          missing_foreign_keys << "  add_foreign_key :#{model.table_name}, :#{target_table}, column: :#{foreign_key}"
        end
      end
    end

    if missing_foreign_keys.empty?
      puts "No missing foreign keys found."
    else
      puts "Add these commands to a migration:\n\n"
      puts missing_foreign_keys.join("\n")
    end
  end
end