如何将对象的字段转储到控制台？

Question

当我运行简单的 Ruby 脚本时，将对象的字段转储到控制台的最简单方法是什么？

我正在寻找类似于 PHP 的 print_r() 的东西，它也适用于数组。

Answer 1

可能：

puts variable.inspect

Answer 2

您可能会发现 methods 方法的用途，它返回对象的方法数组。 它与 print_r 不同，但有时仍然有用。

>> "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"]

Answer 3

to_yaml 方法有时似乎很有用：

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

puts $foo.to_yaml

返回

--- 
:age: 43
:name: Clem

（这是否取决于正在加载的某些 YAML 模块？或者通常可用？）

Answer 4

p object

p 的 Ruby 文档。

p(*args) 公共

对于每个对象，后面直接写obj.inspect
通过程序标准输出的换行符。

Answer 5

如果您只想查找对象中的实例变量，这可能很有用：

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

或者作为复制和粘贴的单行代码：

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

Answer 6

foo.to_json

可能会派上用场，因为默认情况下会加载 json 模块

Answer 7

如果您想打印已经缩进的 JSON：

require 'json'
...
puts JSON.pretty_generate(JSON.parse(object.to_json))

Answer 8

我遇到这个线程是因为我正在寻找类似的东西。 我喜欢这些回复，他们给了我一些想法，所以我测试了 .to_hash 方法，并且对于用例也非常有效。 soo：

object.to_hash

Answer 9

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", "[email protected]", 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] 

Answer 10

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)>

Answer 11

我正在使用自己的解决方案来打印和调试变量 https://github.com/igorkasyanchuk/wrapped_print

您可以简单地调用 user.wp 在日志中查看此变量的值，

而不是：

puts "-"*10
puts user.inspect
puts "-"*10