Ruby-on-rails 如何在 Rails 中打印出对象的内容以便于调试？
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How do I print out the contents of an object in Rails for easy debugging?
提问by cjm2671
I think I'm trying to get the PHP equivalent of print_r()(print human-readable); at present the raw output is:
我想我正在尝试获得相当于print_r()（打印人类可读）的 PHP ；目前原始输出是：
ActiveRecord::Relation:0x10355d1c0
What should I do?
我该怎么办？
回答by jerhinesmith
I generally first try .inspect, if that doesn't give me what I want, I'll switch to .to_yaml.
我通常先尝试.inspect，如果那不能给我想要的，我会切换到.to_yaml.
class User
attr_accessor :name, :age
end
user = User.new
user.name = "John Smith"
user.age = 30
puts user.inspect
#=> #<User:0x423270c @name="John Smith", @age=30>
puts user.to_yaml
#=> --- !ruby/object:User
#=> age: 30
#=> name: John Smith
Hope that helps.
希望有帮助。
回答by Chris Ledet
define the to_s method in your model. For example
在模型中定义 to_s 方法。例如
class Person < ActiveRecord::Base
def to_s
"Name:#{self.name} Age:#{self.age} Weight: #{self.weight}"
end
end
Then when you go to print it with #puts it will display that string with those variables.
然后，当您使用 #puts 打印它时，它将显示带有这些变量的字符串。
回答by ljouglar
回答by Papouche Guinslyzinho
In Rails you can print the result in the View by using the debug' Helper ActionView::Helpers::DebugHelper
在 Rails 中，您可以使用调试的 Helper ActionView::Helpers::DebugHelper在视图中打印结果
#app/view/controllers/post_controller.rb
def index
@posts = Post.all
end
#app/view/posts/index.html.erb
<%= debug(@posts) %>
#start your server
rails -s
results (in browser)
结果（在浏览器中）
- !ruby/object:Post
raw_attributes:
id: 2
title: My Second Post
body: Welcome! This is another example post
published_at: '2015-10-19 23:00:43.469520'
created_at: '2015-10-20 00:00:43.470739'
updated_at: '2015-10-20 00:00:43.470739'
attributes: !ruby/object:ActiveRecord::AttributeSet
attributes: !ruby/object:ActiveRecord::LazyAttributeHash
types: &5
id: &2 !ruby/object:ActiveRecord::Type::Integer
precision:
scale:
limit:
range: !ruby/range
begin: -2147483648
end: 2147483648
excl: true
title: &3 !ruby/object:ActiveRecord::Type::String
precision:
scale:
limit:
body: &4 !ruby/object:ActiveRecord::Type::Text
precision:
scale:
limit:
published_at: !ruby/object:ActiveRecord::AttributeMethods::TimeZoneConversion::TimeZoneConverter
subtype: &1 !ruby/object:ActiveRecord::Type::DateTime
precision:
scale:
limit:
created_at: !ruby/object:ActiveRecord::AttributeMethods::TimeZoneConversion::TimeZoneConverter
subtype: *1
updated_at: !ruby/object:ActiveRecord::AttributeMethods::TimeZoneConversion::TimeZoneConverter
subtype: *1
回答by William Hampshire
.inspectis what you're looking for, it's way easier IMO than .to_yaml!
.inspect就是您要找的东西，IMO 比.to_yaml!
user = User.new
user.name = "will"
user.email = "[email protected]"
user.inspect
#<name: "will", email: "[email protected]">
回答by zee
pp does the job too, no gem requiring is required.
pp 也可以完成这项工作，不需要 gem。
@a = Accrual.first ; pp @a
#<Accrual:0x007ff521e5ba50
id: 4,
year: 2018,
Jan: #<BigDecimal:7ff521e58f08,'0.11E2',9(27)>,
Feb: #<BigDecimal:7ff521e585d0,'0.88E2',9(27)>,
Mar: #<BigDecimal:7ff521e58030,'0.0',9(27)>,
Apr: #<BigDecimal:7ff521e53698,'0.88E2',9(27)>,
May: #<BigDecimal:7ff521e52fb8,'0.8E1',9(27)>,
June: #<BigDecimal:7ff521e52900,'0.8E1',9(27)>,
July: #<BigDecimal:7ff521e51ff0,'0.8E1',9(27)>,
Aug: #<BigDecimal:7ff521e51bb8,'0.88E2',9(27)>,
Sep: #<BigDecimal:7ff521e512f8,'0.88E2',9(27)>,
Oct: #<BigDecimal:7ff521e506c8,'0.0',9(27)>,
Nov: #<BigDecimal:7ff521e43d38,'0.888E3',9(27)>,
Dec: #<BigDecimal:7ff521e43478,'0.0',9(27)>,
You can also print two instances of an object:
您还可以打印一个对象的两个实例：
pp( Accrual.first , Accrual.second)
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回答by thisismydesign
inspectis great but sometimes not good enough. E.g. BigDecimalprints like this: #<BigDecimal:7ff49f5478b0,'0.1E2',9(18)>.
inspect很棒，但有时还不够好。例如，BigDecimal打印这样的：#<BigDecimal:7ff49f5478b0,'0.1E2',9(18)>。
To have full control over what's printed you could redefine to_sor inspectmethods. Or create your own one to not confuse future devs too much.
要完全控制打印的内容，您可以重新定义to_s或inspect方法。或者创建自己的一个，以免混淆未来的开发人员。
class Something < ApplicationRecord
def to_s
attributes.map{ |k, v| { k => v.to_s } }.inject(:merge)
end
end
This will apply a method (i.e. to_s) to all attributes. This example will get rid of the ugly BigDecimals.
这将对to_s所有属性应用一个方法（即）。这个例子将摆脱丑陋的BigDecimals.
You can also redefine a handful of attributes only:
您还可以仅重新定义少数属性：
def to_s
attributes.merge({ my_attribute: my_attribute.to_s })
end
You can also create a mix of the two or somehowadd associations.
您还可以创建两者的混合或以某种方式添加关联。
回答by Andrew
You need to use debug(@var). It's exactly like "print_r".
您需要使用debug(@var). 它就像“print_r”。
