298

When I'm running a simple Ruby script, what's the easiest way to dump an object's fields to the console?

I'm looking for something similar to PHP's print_r() that will work with arrays as well.

4

11 回答 11

462

Possibly:

puts variable.inspect
于 2008-12-09T23:08:27.030 回答
57

You might find a use for the methods method which returns an array of methods for an object. It's not the same as print_r, but still useful at times.

>> "Hello".methods.sort
=> ["%", "*", "+", "<", "<<", "<=", "<=>", "==", "===", "=~", ">", ">=", "[]", "[]=", "__id__", "__send__", "all?", "any?", "between?", "capitalize", "capitalize!", "casecmp", "center", "chomp", "chomp!", "chop", "chop!", "class", "clone", "collect", "concat", "count", "crypt", "delete", "delete!", "detect", "display", "downcase", "downcase!", "dump", "dup", "each", "each_byte", "each_line", "each_with_index", "empty?", "entries", "eql?", "equal?", "extend", "find", "find_all", "freeze", "frozen?", "grep", "gsub", "gsub!", "hash", "hex", "id", "include?", "index", "inject", "insert", "inspect", "instance_eval", "instance_of?", "instance_variable_defined?", "instance_variable_get", "instance_variable_set", "instance_variables", "intern", "is_a?", "is_binary_data?", "is_complex_yaml?", "kind_of?", "length", "ljust", "lstrip", "lstrip!", "map", "match", "max", "member?", "method", "methods", "min", "next", "next!", "nil?", "object_id", "oct", "partition", "private_methods", "protected_methods", "public_methods", "reject", "replace", "respond_to?", "reverse", "reverse!", "rindex", "rjust", "rstrip", "rstrip!", "scan", "select", "send", "singleton_methods", "size", "slice", "slice!", "sort", "sort_by", "split", "squeeze", "squeeze!", "strip", "strip!", "sub", "sub!", "succ", "succ!", "sum", "swapcase", "swapcase!", "taguri", "taguri=", "taint", "tainted?", "to_a", "to_f", "to_i", "to_s", "to_str", "to_sym", "to_yaml", "to_yaml_properties", "to_yaml_style", "tr", "tr!", "tr_s", "tr_s!", "type", "unpack", "untaint", "upcase", "upcase!", "upto", "zip"]
于 2008-12-09T23:33:06.140 回答
52

The to_yaml method seems to be useful sometimes:

$foo = {:name => "Clem", :age => 43}

puts $foo.to_yaml

returns

--- 
:age: 43
:name: Clem

(Does this depend on some YAML module being loaded? Or would that typically be available?)

于 2009-10-06T23:54:29.557 回答
33 
p object

Ruby doc for p.

p(*args) public

For each object, directly writes obj.inspect followed by a newline to the program’s standard output.

于 2008-12-10T03:34:19.567 回答
16

If you're looking for just the instance variables in the object, this might be useful:

obj.instance_variables.each do |var|
  puts [var, obj.instance_variable_get(var).inspect].join(":")
end

or as a one-liner for copy and pasting:

obj.instance_variables.each{ |var| puts [var, obj.instance_variable_get(var).inspect].join(":")}
于 2013-01-14T15:23:24.493 回答
10

puts foo.to_json

might come in handy since the json module is loaded by default

于 2010-08-20T09:55:49.170 回答
5

If you want to print an already indented JSON:

require 'json'
...
puts JSON.pretty_generate(JSON.parse(object.to_json))
于 2016-11-17T08:26:35.447 回答
5

I came across this thread because I was looking for something similar. I like the responses and they gave me some ideas so I tested the .to_hash method and worked really well for the use case too. soo:

object.to_hash

于 2017-07-21T13:53:05.997 回答
3 
object.attribute_names

# => ["id", "name", "email", "created_at", "updated_at", "password_digest", "remember_token", "admin", "marketing_permissions", "terms_and_conditions", "disable", "black_list", "zero_cost", "password_reset_token", "password_reset_sent_at"]


object.attributes.values

# => [1, "tom", "tom@tom.com", Tue, 02 Jun 2015 00:16:03 UTC +00:00, Tue, 02 Jun 2015 00:22:35 UTC +00:00, "$2a$10$gUTr3lpHzXvCDhVvizo8Gu/MxiTrazOWmOQqJXMW8gFLvwDftF9Lm", "2dd1829c9fb3af2a36a970acda0efe5c1d471199", true, nil, nil, nil, nil, nil, nil, nil]
于 2015-06-03T21:56:41.547 回答
0

pp File.stat('/tmp')

#<File::Stat
 dev=0x1000004,
 ino=71426291,
 mode=041777 (directory rwxrwxrwt),
 nlink=15,
 uid=0 (root),
 gid=0 (wheel),
 rdev=0x0 (0, 0),
 size=480,
 blksize=4096,
 blocks=0,
 atime=2021-04-20 17:50:33.062419819 +0800 (1618912233),
 mtime=2021-04-21 11:35:32.808546288 +0800 (1618976132),
 ctime=2021-04-21 11:35:32.808546288 +0800 (1618976132)>
于 2021-04-21T03:38:53.553 回答
0

I'm using own solution to print and debug variables is https://github.com/igorkasyanchuk/wrapped_print

you can simply call user.wp to see in the logs a value of this variable

instead of:

puts "-"*10
puts user.inspect
puts "-"*10
于 2021-06-25T06:02:32.193 回答