Maybe/app/controllers/transactions/merchants_controller.rb

class Transactions::MerchantsController < ApplicationController
  before_action :set_merchant, only: %i[ edit update destroy ]

  def index
    @merchants = Current.family.transaction_merchants
  end

  def new
    @merchant = Transaction::Merchant.new
  end

  def create
    if Current.family.transaction_merchants.create(merchant_params)
      redirect_to transactions_merchants_path, notice: t(".success")
    else
      render transactions_merchants_path, status: :unprocessable_entity, notice: t(".error")
    end
  end

  def edit
  end

  def update
    if @merchant.update(merchant_params)
      redirect_to transactions_merchants_path, notice: t(".success")
    else
      render transactions_merchants_path, status: :unprocessable_entity, notice: t(".error")
    end
  end

  def destroy
    @merchant.destroy!
    redirect_to transactions_merchants_path, notice: t(".success")
  end

  private

  def set_merchant
    @merchant = Current.family.transaction_merchants.find(params[:id])
  end

  def merchant_params
    params.require(:transaction_merchant).permit(:name, :color)
  end
end