Rails PG:唯一约束的错误表示和处理

Question

我正在使用postgres和design开发Rails 4。我有以下用户模型:

# user model
class User < ActiveRecord::Base
  extend FriendlyId
  friendly_id :username, :use => :slugged
  rolify
  devise :database_authenticatable, :registerable, :recoverable, :rememberable, :trackable
  validates :username, :presence => true, :uniqueness => {:case_sensitive => false}, :length => { :minimum => 3 },
            :format => { :with => /A[A-Z0-9a-zwb -_'!&@#.]+z/i,
              :message => "may contain only alphanumeric characters and common special characters." }
  validates :email, :uniqueness => {:case_sensitive => false}, :presence => true, 
            :format => { :with => Devise.email_regexp, :message => "isn't valid"}
  validates :password, length: { in: 6..128 }, on: :create
  validates :password, length: { in: 6..128 }, on: :update, allow_blank: true
  validates :slug, :presence => true
end

# in schema
create_table "users", force: true do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "username"
    t.string   "slug"
  end
  add_index "users", ["email"], name: "index_users_on_email", unique: true
  add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
  add_index "users", ["slug"], name: "index_users_on_slug", unique: true
  add_index "users", ["username"], name: "index_users_on_username", unique: true

字段email和username是users表的唯一索引。我的用户注册视图是从设计中创建的。例如，我创建了一个测试帐户，用户名为"test"，电子邮件为"[e-mail]"，密码为"123456"。我退出并尝试用相同的信息注册。我期望:唯一性验证触发并呈现在注册表单旁边的错误列表上，但我得到了一个完整的页面错误:

错误:重复键值违反唯一约束"index_users_on_email"DETAIL: Key (email)=([e-mail])已经存在。

我怎么能让这个错误冒泡到Rails，并显示为友好的单行错误，如"电子邮件已经注册了一个帐户"旁边的注册表单，而不是被捕获与一个大的Rails错误页面?

Answer 1

我已经发现了问题。插件friendly_id结果不那么友好。它破坏唯一性验证并导致500个内部服务器错误。我已经把它从我的申请中删除了。考虑在Stringex库中使用ActsAsUrl之类的东西。我已经删除了

  extend FriendlyId
  friendly_id :username_copy, :use => :slugged

，我现在使用

acts_as_url :username, :sync_url => true, :url_attribute => :slug

生成友好的url。