Make Active Storage blob keys lowercase

Accommodate case-insensitive filesystems and database collations.

2 files changed, 43 insertions, 3 deletions

diff --git a/activesupport/lib/active_support/core_ext/securerandom.rb b/activesupport/lib/active_support/core_ext/securerandom.rb
index b4a491f5fd..ef812f7e1a 100644
--- a/activesupport/lib/active_support/core_ext/securerandom.rb
+++ b/activesupport/lib/active_support/core_ext/securerandom.rb
@@ -4,17 +4,18 @@ require "securerandom"
 
 module SecureRandom
   BASE58_ALPHABET = ("0".."9").to_a + ("A".."Z").to_a + ("a".."z").to_a - ["0", "O", "I", "l"]
+  BASE36_ALPHABET = ("0".."9").to_a + ("a".."z").to_a
+
   # SecureRandom.base58 generates a random base58 string.
   #
-  # The argument _n_ specifies the length, of the random string to be generated.
+  # The argument _n_ specifies the length of the random string to be generated.
   #
   # If _n_ is not specified or is +nil+, 16 is assumed. It may be larger in the future.
   #
-  # The result may contain alphanumeric characters except 0, O, I and l
+  # The result may contain alphanumeric characters except 0, O, I and l.
   #
   #   p SecureRandom.base58 # => "4kUgL2pdQMSCQtjE"
   #   p SecureRandom.base58(24) # => "77TMHrHJFvFDwodq8w7Ev2m7"
-  #
   def self.base58(n = 16)
     SecureRandom.random_bytes(n).unpack("C*").map do |byte|
       idx = byte % 64
@@ -22,4 +23,23 @@ module SecureRandom
       BASE58_ALPHABET[idx]
     end.join
   end
+
+  # SecureRandom.base36 generates a random base36 string in lowercase.
+  #
+  # The argument _n_ specifies the length of the random string to be generated.
+  #
+  # If _n_ is not specified or is +nil+, 16 is assumed. It may be larger in the future.
+  # This method can be used over +base58+ if a deterministic case key is necessary.
+  #
+  # The result will contain alphanumeric characters in lowercase.
+  #
+  #   p SecureRandom.base36 # => "4kugl2pdqmscqtje"
+  #   p SecureRandom.base36(24) # => "77tmhrhjfvfdwodq8w7ev2m7"
+  def self.base36(n = 16)
+    SecureRandom.random_bytes(n).unpack("C*").map do |byte|
+      idx = byte % 64
+      idx = SecureRandom.random_number(36) if idx >= 36
+      BASE36_ALPHABET[idx]
+    end.join
+  end
 end
diff --git a/activesupport/test/core_ext/secure_random_test.rb b/activesupport/test/core_ext/secure_random_test.rb
index 7067fb524c..88c8a37c5d 100644
--- a/activesupport/test/core_ext/secure_random_test.rb
+++ b/activesupport/test/core_ext/secure_random_test.rb
@@ -19,4 +19,24 @@ class SecureRandomTest < ActiveSupport::TestCase
     assert_not_equal s1, s2
     assert_equal 24, s1.length
   end
+
+  def test_base36_lowercase
+    s1 = SecureRandom.base36
+    s2 = SecureRandom.base36
+
+    assert_not_equal s1, s2
+    assert_equal 16, s1.length
+    assert_match(/^[a-z0-9]+$/, s1)
+    assert_match(/^[a-z0-9]+$/, s2)
+  end
+
+  def test_base36_with_length
+    s1 = SecureRandom.base36(24)
+    s2 = SecureRandom.base36(24)
+
+    assert_not_equal s1, s2
+    assert_equal 24, s1.length
+    assert_match(/^[a-z0-9]+$/, s1)
+    assert_match(/^[a-z0-9]+$/, s2)
+  end
 end