从用户模型 devise 部分删除可验证选项验证电子邮件地址的存在，唯一性和格式。不过，您必须手动添加自己的密码存在，确认和长度的验证。

I'm using Rails 4.0 and Devise 3.0.0.rc.

I installed Devise with its defaults - i.e. sign up/in using your email address. However, I'd like the users to be able to sign up with a username instead of their email address. I've followed the railscasts in terms of which parameters to change, plus any advice I can find on here for things I might need to change for Rails 4. However, whenever I try to create a new user, I am getting the error 'email can't be blank'. Does anyone have an idea as to what is causing this, and how I can fix it? Thanks!!

Code:

application controller:

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception
  before_filter :configure_permitted_parameters, if: :devise_controller?

  protected

   def configure_permitted_parameters
      devise_parameter_sanitizer.for(:sign_up) { |u| u.permit(:username, :password, :password_confirmation) }
      devise_parameter_sanitizer.for(:sign_in) { |u| u.permit(:username, :password, :remember_me) }
    end
end

Sign in (sign up form is pretty much the same):

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

In devise.rb config:

config.authentication_keys = [ :username ]

users controller:

private
    # Use callbacks to share common setup or constraints between actions.
    def set_user
      @user = User.find(params[:id])
    end

# Never trust parameters from the scary internet, only allow the white list through.
def user_params
  params.require(:user).permit(:first_name, :middle_names, :last_name, :date_of_birth, :gender, :line_1, :line_2, :line_3, :town, :county, :postcode, :contact_number, :email, :username, :password, :password_confirmation, :remember_me)
end

user.rb:

protected

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

Remove validatable from the User model devise section - this option validates the presence, uniqueness and format of the email address. You'll have to manually add your own validations for password presence, confirmation and length, though.