Return a hash rather than array from fetch_multi

The current implementation of `fetch_multi` returns an array and has no
means to easily backtrack which names yielded which results. By changing
the return value to a Hash we retain the name information. Hash#values
can be used on the response if only the values are needed.

1 files changed, 5 insertions, 6 deletions

diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index 2b7f5943b5..a627fa8651 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -357,20 +357,19 @@ module ActiveSupport
       #
       # Options are passed to the underlying cache implementation.
       #
-      # Returns an array with the data for each of the names. For example:
+      # Returns a hash with the data for each of the names. For example:
       #
       #   cache.write("bim", "bam")
-      #   cache.fetch_multi("bim", "boom") {|key| key * 2 }
-      #   # => ["bam", "boomboom"]
+      #   cache.fetch_multi("bim", "boom") { |key| key * 2 }
+      #   # => { "bam" => "bam", "boom" => "boomboom" }
       #
       def fetch_multi(*names)
         options = names.extract_options!
         options = merged_options(options)
-
         results = read_multi(*names, options)
 
-        names.map do |name|
-          results.fetch(name) do
+        names.each_with_object({}) do |name, memo|
+          memo[name] = results.fetch(name) do
             value = yield name
             write(name, value, options)
             value