How to generate a random string in Ruby

Another trick that works with Ruby 1.8+ and is fast is:

>> require "openssl"
>> OpenSSL::Random.random_bytes(20).unpack('H*').join
=> "2f3ff53dd712ba2303a573d9f9a8c1dbc1942d28"

It get's you random hex string. Similar way you should be able to generate base64 string ('M*').

If you want a string of specified length, use:


require 'securerandom'
randomstring = SecureRandom.hex(n)

It will generate a random string of length `2n` containing `0-9` and `a-f`

Why not use SecureRandom?

require 'securerandom'
random_string = SecureRandom.hex

# outputs: 5b5cd0da3121fc53b4bc84d0c8af2e81 (i.e. 32 chars of 0..9, a..f)

SecureRandom also has methods for:

- base64
- random_bytes
- random_number

see: [

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This solution needs external dependency, but seems prettier than another.

1. Install gem [faker][1]
2. `Faker::Lorem.characters(10) # => "ang9cbhoa8"`


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10.times do
alphabet = ('a'..'z').to_a
string += alpha[rand(alpha.length)]
end

Ruby 1.9+:

ALPHABET = ('a'..'z').to_a
#=> ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

10.times.map { ALPHABET.sample }.join
#=> "stkbssowre"

# or

10.times.inject('') { |s| s + ALPHABET.sample }
#=> "fdgvacnxhc"

a='';8.times{a<<[*'a'..'z'].sample};p a

or

8.times.collect{[*'a'..'z'].sample}.join

Given:

chars = [*('a'..'z'),*('0'..'9')].flatten

Single expression, can be passed as an argument, allows duplicate characters:

Array.new(len) { chars.sample }.join

Here is a improve of @Travis R answer:

def random_string(length=5)
chars = 'abdefghjkmnpqrstuvwxyzABDEFGHJKLMNPQRSTUVWXYZ'
numbers = '0123456789'
random_s = ''
(length/2).times { random_s << numbers[rand(numbers.size)] }
(length - random_s.length).times { random_s << chars[rand(chars.size)] }
random_s.split('').shuffle.join
end

At @Travis R answer chars and numbers were together, so sometimes `random_string` could return only numbers or only characters. With this improve at least half of `random_string` will be characters and the rest are numbers. Just in case if you need a random string with numbers and characters

Use 'SafeRandom' Gem [GithubLink][1]

It will provide the easiest way to generate random values for Rails2, Rails 3, Rails 4, Rails 5 compatible.

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