在一个字段Rails中使用2个参数的devise登录

gem 'devise'

rails generate devise:install
rails generate devise User

# config.authentication_keys = [ :email ]

config.authentication_keys = [:username, :email]

attr_accessor :login

def self.find_for_database_authentication(warden_conditions)
  conditions = warden_conditions.dup
  if login = conditions.delete(:login)
    where(conditions.to_h).where(["lower(username) = :value OR lower(email) = :value", { :value => login.downcase }]).first
  else
    where(conditions.to_h).first
  end
end

validate :validate_username

def validate_username
  if User.where(email: username).exists?
    errors.add(:username, :invalid)
  end
end

def login=(login)
  @login = login
end

def login
  @login || self.username || self.email
end

<%= form_for(resource, as: resource_name, url: session_path(resource_name)) do |f| %>
  <div class="field">
    <%= f.label :login %>
    <%= f.text_field :login, autofocus: true %>
  </div>

  <div class="field">
    <%= f.label :password %>
    <%= f.password_field :password, autocomplete: "current-password" %>
  </div>

  <% if devise_mapping.rememberable? -%>
    <div class="field">
      <%= f.check_box :remember_me %>
      <%= f.label :remember_me %>
    </div>
  <% end -%>

  <div class="actions">
    <%= f.submit "Log in" %>
  </div>
<% end %>