Is there a print_r or var_dump equivalent in Ruby / Ruby on Rails?

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In views:

include DebugHelper


...your code...


debug(object)

In controllers, models, and other code:

puts YAML::dump(object)

Source

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最佳答案

The .inspect method of any object should format is correctly for display, just do..

<%= theobject.inspect %>

The .methods method may also be of use:

<%= theobject.methods.inspect %>

It may help to put that in <pre> tags, depending on the data

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If you just want the relevant data to be displayed to stdout (the terminal output if you're running from the command line), you can use p some_object.

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In a view you can use <%= debug(yourobject) %> which will generate a YAML view of your data. If you want something in your log you should use logger.debug yourobject.inspect.

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You can also use YAML::dump shorthand (y) under Rails console:

>> y User.first
--- !ruby/object:User
attributes:
created_at: 2009-05-24 20:16:11.099441
updated_at: 2009-05-26 22:46:29.501245
current_login_ip: 127.0.0.1
id: "1"
current_login_at: 2009-05-24 20:20:46.627254
login_count: "1"
last_login_ip:
last_login_at:
login: admin
attributes_cache: {}


=> nil
>>

If you want to just preview some string contents, try using raise (for example in models, controllers or some other inaccessible place). You get the backtrace for free:)

>> raise Rails.root
RuntimeError: /home/marcin/work/github/project1
from (irb):17
>>

I also really encourage you to try ruby-debug:

It's incredibly helpful!

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I use this :)

require 'yaml'


module AppHelpers
module Debug
module VarDump


class << self


def dump(dump_object, file_path)
File.open file_path, "a+" do |log_file|
current_date = Time.new.to_s + "\n" + YAML::dump(dump_object) + "\n"
log_file.puts current_date
log_file.close
end
end


end


end
end
end

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Lately I'm using awesome_print's ap method which works on the console as well as in views.

The type-specific colored output really makes a difference if you need to visually scan for String or Numeric objects (Although I had to tweak my stylesheet a little bit in order to get a polished look)

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Recently I have become a fan of PRY, I've found it incredibly for doing things like inspecting variables, debugging running code and inspecting external code. It might be a little overkill as an answer to this specific question.

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You can use puts some_variable.inspect. Or the shorter version: p some_variable. And for prettier output, you can use the awesome_print gem.

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Prrevious answers are great but if you don't want to use the console (terminal), in Rails you can print the result in the View by using the debug's Helper ActionView::Helpers::DebugHelper

#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)

- !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