Added code for defining SHA attributes

These attributes are stored in binary in the database, but exposed as
strings. This allows one to query/create data using plain SHA1 hashes as
Strings, while storing them more efficiently as binary.

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/gitlab/database/sha_attribute.rb b/lib/gitlab/database/sha_attribute.rb
new file mode 100644
index 00000000000..d9400e04b83
--- /dev/null
+++ b/lib/gitlab/database/sha_attribute.rb
@@ -0,0 +1,34 @@
+module Gitlab
+  module Database
+    BINARY_TYPE = if Gitlab::Database.postgresql?
+                    # PostgreSQL defines its own class with slightly different
+                    # behaviour from the default Binary type.
+                    ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Bytea
+                  else
+                    ActiveRecord::Type::Binary
+                  end
+
+    # Class for casting binary data to hexadecimal SHA1 hashes (and vice-versa).
+    #
+    # Using ShaAttribute allows you to store SHA1 values as binary while still
+    # using them as if they were stored as string values. This gives you the
+    # ease of use of string values, but without the storage overhead.
+    class ShaAttribute < BINARY_TYPE
+      PACK_FORMAT = 'H*'.freeze
+
+      # Casts binary data to a SHA1 in hexadecimal.
+      def type_cast_from_database(value)
+        value = super
+
+        value ? value.unpack(PACK_FORMAT)[0] : nil
+      end
+
+      # Casts a SHA1 in hexadecimal to the proper binary format.
+      def type_cast_for_database(value)
+        arg = value ? [value].pack(PACK_FORMAT) : nil
+
+        super(arg)
+      end
+    end
+  end
+end