Rails路由到用户名而不是id

def to_param
  username
end

validates :username, presence: true, uniqueness: true

def self.find_by_username(username)
  where("LOWER(username) = ?", username.downcase).first
end

before_action :convert_username_to_lowercase

def convert_username_to_lowercase
  params[:id] = params[:id].downcase if params[:controller] == 'users' && params[:action] == 'show'
end

<%= link_to user.username, user_path(user.username) %>