How do I dump an object's fields to the console?
RubyPrintf DebuggingRuby Problem Overview
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.
Ruby Solutions
Solution 1 - Ruby
Possibly:
puts variable.inspect
Solution 2 - Ruby
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"]
Solution 3 - Ruby
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?)
Solution 4 - Ruby
p object
> p(*args) public
>
> For each object, directly writes obj.inspect followed
> by a newline to the program’s standard output.
Solution 5 - Ruby
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(":")}
Solution 6 - Ruby
puts foo.to_json
might come in handy since the json module is loaded by default
Solution 7 - Ruby
If you want to print an already indented JSON:
require 'json'
...
puts JSON.pretty_generate(JSON.parse(object.to_json))
Solution 8 - Ruby
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
Solution 9 - Ruby
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]
Solution 10 - Ruby
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)>
Solution 11 - Ruby
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