强制rails（控制台和服务器）错误默认完整显示？

Question

我经常需要查看与ROLLBACKs 相关的各种数据库相关的错误消息，类似于here：

project = Project.find 118
project.assign_attributes(featured: true)
project.valid?
project.errors.full_messages

简单地附加.errors.full_messages 并不太费力，但是，当我们还没有实例化某个对象（在本例中为project）时，它变得更加乏味，因为必须实例化一个对象，这涉及更改代码（只需查看错误消息）。

例子：

User.create(name: "john", email: "john@gmail.com", .... etc)

必须重构为类似

user = User.new(name: "john", email: "john@gmail.com", .... etc)
user.save

# then type

user.errors.full_messages

所有这些都是为了简单地看到一条错误消息。

问题

是否有某种方法可以让错误消息总是显示（完整），而无需专门使用 .errors.full_messages 之类的东西来请求它们？ （在 Rails 控制台和服务器中）

我会尝试任何事情 - 全局设置、宝石、黑客 - 不惜一切

Answer 1

使用 bang (!)。

在需要很多东西（包括标题）的模型上，create 失败并触发您的回滚：

> Post.create(title: nil)
   (0.1ms)  BEGIN
  Post Exists (0.2ms)  SELECT  1 AS one FROM "posts" WHERE "posts"."slug" IS NULL LIMIT $1  [["LIMIT", 1]]
   (0.1ms)  ROLLBACK
=> #<Post:0x007fa44c934fc0
 id: nil,
 developer_id: nil,
 body: nil,
 created_at: nil,
 updated_at: nil,
 channel_id: nil,
 title: nil,
 slug: nil,
 likes: 1,
 tweeted: false,
 published_at: nil,
 max_likes: 1>

随着一声巨响，创建快速失败并引发RecordInvalid 错误：

> Post.create!(title: nil)
   (0.1ms)  BEGIN
  Post Exists (0.2ms)  SELECT  1 AS one FROM "posts" WHERE "posts"."slug" IS NULL LIMIT $1  [["LIMIT", 1]]
   (0.1ms)  ROLLBACK
ActiveRecord::RecordInvalid: Validation failed: Body can't be blank, Channel can't be blank, Developer can't be blank, Title can't be blank
from /Users/dev/.asdf/installs/ruby/2.3.3/lib/ruby/gems/2.3.0/gems/activerecord-5.0.1/lib/active_record/validations.rb:78:in `raise_validation_error'

要在 OP 上进行构建，可以使用 update_attributes 和 update_attributes! 来产生两种行为：

> Post.first.update_attributes(title: nil)
  Post Load (0.2ms)  SELECT  "posts".* FROM "posts" ORDER BY "posts"."id" ASC LIMIT $1  [["LIMIT", 1]]
   (0.1ms)  BEGIN
  Developer Load (0.2ms)  SELECT  "developers".* FROM "developers" WHERE "developers"."id" = $1 LIMIT $2  [["id", 4], ["LIMIT", 1]]
  Post Exists (0.2ms)  SELECT  1 AS one FROM "posts" WHERE "posts"."slug" = $1 AND ("posts"."id" != $2) LIMIT $3  [["slug", "81e668bc4e"], ["id", 1], ["LIMIT", 1]]
   (0.1ms)  ROLLBACK
=> false

> Post.first.update_attributes!(title: nil)
  Post Load (0.2ms)  SELECT  "posts".* FROM "posts" ORDER BY "posts"."id" ASC LIMIT $1  [["LIMIT", 1]]
   (0.1ms)  BEGIN
  Developer Load (0.2ms)  SELECT  "developers".* FROM "developers" WHERE "developers"."id" = $1 LIMIT $2  [["id", 4], ["LIMIT", 1]]
  Post Exists (0.2ms)  SELECT  1 AS one FROM "posts" WHERE "posts"."slug" = $1 AND ("posts"."id" != $2) LIMIT $3  [["slug", "81e668bc4e"], ["id", 1], ["LIMIT", 1]]
   (0.1ms)  ROLLBACK
ActiveRecord::RecordInvalid: Validation failed: Title can't be blank
from /Users/dev/.asdf/installs/ruby/2.3.3/lib/ruby/gems/2.3.0/gems/activerecord-5.0.1/lib/active_record/validations.rb:78:in `raise_validation_error'

什么是!？

! 在 Ruby 中通常意味着该方法将修改它所调用的对象。但是，ActiveRecord 有不同的约定； ! 方法“更严格，因为它们会引发异常。”

create docs validation docs