Question

我正在构建的应用程序包含一个联系表单。播种时会生成一条我不理解的错误消息：

ActiveRecord::StatementInvalid: PG::NotNullViolation: ERROR:  null value in column "name" violates not-null constraint
DETAIL:  Failing row contains (1, null, null, null, 2015-06-06 13:43:12.339477, 2015-06-06 13:43:12.339477).
: INSERT INTO "messages" ("created_at", "updated_at") VALUES ($1, $2) RETURNING "id"

以下是表单的相关代码。如果我从模型文件中删除行attr_accessor :name, :email, :content，它就会成功播种（我不知道为什么这会对播种产生影响）。但即便如此，在开发服务器上，如果我转到联系表单并提交没有任何值，则错误消息似乎无法正常运行。无论错误如何，它只会给出一条错误消息“传递此消息时发生错误”，而对于所有其他形式，错误消息指定了变量和错误类型。可能导致这种行为的原因是什么？

联系表格的模型文件：

class Message < ActiveRecord::Base
  attr_accessor :name, :email, :content
  validates :name,      presence: true,
                        length: { maximum: 255 }
  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-]+(\.[a-z\d\-]+)*\.[a-z]+\z/i
  validates :email,     presence: true,
                        length: { maximum: 255 },
                        format: { with: VALID_EMAIL_REGEX }
  validates :content,   presence: true,
                        length: { maximum: 600 }
end

迁移文件包括：

  t.string :name,       null: false,    limit: 255
  t.string :email,      null: false,    limit: 255
  t.string :content,    null: false,    limit: 600

在我的种子文件中，我有：

Message.create!(email: "example@example.com",
                name:  "Example User",
                content: "This is my message")

更新：关于错误消息，我有以下控制器方法：

  def create
    @message = Message.new(message_params)
    if @message.valid?
      MessageMailer.new_message(@message).deliver_now
      flash[:success] = "Your messages has been sent."
      redirect_to contact_path
    else
      flash[:alert] = "An error occurred while delivering this message."
      render 'new'
    end
  end

我删除了闪光警报线。我有其他正常运行的表单，也没有这一行，虽然这个flash消息可能会覆盖其他更具体的错误消息。删除此行并提交无效信息后，表单只会使无效字段变为红色，但根本不显示任何错误消息。在其他形式中，我会例如得到这些错误消息：

 The form contains 5 errors.
    Email can't be blank
    Email is invalid
    Username can't be blank
    Username is too short (minimum is 6 characters)
    Username is invalid

日志文件是：

Started GET "/contact" for xx.xxx.xx.xxx at 2015-06-06 14:15:43 +0000
  ActiveRecord::SchemaMigration Load (0.5ms)  SELECT "schema_migrations".* FROM "schema_migrations"
Processing by MessagesController#new as HTML
  Rendered messages/new.html.erb within layouts/application (493.2ms)
  Rendered layouts/_shim.html.erb (0.4ms)
  Rendered layouts/_header.html.erb (10.5ms)
  Rendered layouts/_footer.html.erb (0.8ms)
Completed 200 OK in 1454ms (Views: 1429.3ms | ActiveRecord: 3.1ms)

Started POST "/contact" for xx.xxx.xx.xxx at 2015-06-06 14:15:49 +0000
Processing by MessagesController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"zAxxxSKMYKey/jxmqqvxxxr***43g2Ud9r6SQ==", "message"=>{"name"=>"", "email"=>"", "content"=>""}, "commit"=>"Send"}
  Rendered messages/new.html.erb within layouts/application (7.3ms)
  Rendered layouts/_shim.html.erb (0.1ms)
  Rendered layouts/_header.html.erb (3.2ms)
  Rendered layouts/_footer.html.erb (0.3ms)
Completed 200 OK in 849ms (Views: 844.9ms | ActiveRecord: 0.0ms)

Answer 1

添加attr_accessor :name等同于以下代码

def name
  @name
end

def name=(val)
  @name = val
end

因此，如果您的数据库中有一个名为name的列，则不会编写该列。这就是这里发生的事情。由于您将这些列设置为null: false，因此如果postgres为null则会引发错误。

联系表单：种子错误和表单错误消息无法正常工作

1 个答案: