Add `ActionController::Parameters#dig`

This method will only be added when used with Ruby 2.3.0 or greater.
This method has the same behavior as `Hash#dig`, except it will convert
hashes to `ActionController::Parameters`, similar to `#[]` and `#fetch`.

1 files changed, 15 insertions, 0 deletions

diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index a01110d474..6d59e32c68 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -430,6 +430,21 @@ module ActionController
       )
     end
 
+    if Hash.method_defined?(:dig)
+      # Extracts the nested parameter from the given +keys+ by calling +dig+
+      # at each step. Returns +nil+ if any intermediate step is +nil+.
+      #
+      # params = ActionController::Parameters.new(foo: { bar: { baz: 1 } })
+      # params.dig(:foo, :bar, :baz) # => 1
+      # params.dig(:foo, :zot, :xyz) # => nil
+      #
+      # params2 = ActionController::Parameters.new(foo: [10, 11, 12])
+      # params2.dig(:foo, 1)
+      def dig(*keys)
+        convert_value_to_parameters(@parameters.dig(*keys))
+      end
+    end
+
     # Returns a new <tt>ActionController::Parameters</tt> instance that
     # includes only the given +keys+. If the given +keys+
     # don't exist, returns an empty hash.