5 files changed, 105 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index 6a07a73d94..27c2a8db36 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -744,6 +744,18 @@ module ActionController
     end
     alias_method :delete_if, :reject!
 
+    # Returns a new instance of <tt>ActionController::Parameters</tt> without the blank values.
+    # Uses Object#blank? for determining if a value is blank.
+    def compact_blank
+      reject { |_k, v| v.blank? }
+    end
+
+    # Removes all blank values in place and returns self.
+    # Uses Object#blank? for determining if a value is blank.
+    def compact_blank!
+      reject! { |_k, v| v.blank? }
+    end
+
     # Returns values that were assigned to the given +keys+. Note that all the
     # +Hash+ objects will be converted to <tt>ActionController::Parameters</tt>.
     def values_at(*keys)
diff --git a/actionpack/test/controller/parameters/mutators_test.rb b/actionpack/test/controller/parameters/mutators_test.rb
index 31ee7964f5..ffffd2996f 100644
--- a/actionpack/test/controller/parameters/mutators_test.rb
+++ b/actionpack/test/controller/parameters/mutators_test.rb
@@ -127,4 +127,22 @@ class ParametersMutatorsTest < ActiveSupport::TestCase
   test "deep_transform_keys! retains unpermitted status" do
     assert_not_predicate @params.deep_transform_keys! { |k| k }, :permitted?
   end
+
+  test "compact_blank retains permitted status" do
+    @params.permit!
+    assert_predicate @params.compact_blank, :permitted?
+  end
+
+  test "compact_blank retains unpermitted status" do
+    assert_not_predicate @params.compact_blank, :permitted?
+  end
+
+  test "compact_blank! retains permitted status" do
+    @params.permit!
+    assert_predicate @params.compact_blank!, :permitted?
+  end
+
+  test "compact_blank! retains unpermitted status" do
+    assert_not_predicate @params.compact_blank!, :permitted?
+  end
 end
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 955eb7eef9..6256fb8c86 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   Add `compact_blank` for those times when you want to remove #blank? values from
+    an Enumerable (also `compact_blank!` on Hash, Array, ActionController::Parameters)
+
+    *Dana Sherson*
+
 *   `delegate_missing_to` would raise a `DelegationError` if the object
     delegated to was `nil`. Now the `allow_nil` option has been added to enable
     the user to specify they want `nil` returned in this case.
diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb
index 4675c41936..728d332306 100644
--- a/activesupport/lib/active_support/core_ext/enumerable.rb
+++ b/activesupport/lib/active_support/core_ext/enumerable.rb
@@ -148,6 +148,41 @@ module Enumerable
       map { |element| element[keys.first] }
     end
   end
+
+  # Returns a new +Array+ without the blank items.
+  # Uses Object#blank? for determining if an item is blank.
+  #
+  #    [1, "", nil, 2, " ", [], {}, false, true].compact_blank
+  #    # =>  [1, 2, true]
+  #
+  #    Set.new([nil, "", 1, 2])
+  #    # => [2, 1] (or [1, 2])
+  #
+  # When called on a +Hash+, returns a new +Hash+ without the blank values.
+  #
+  #    { a: "", b: 1, c: nil, d: [], e: false, f: true }.compact_blank
+  #    #=> { b: 1, f: true }
+  def compact_blank
+    reject(&:blank?)
+  end
+end
+
+class Hash
+  # Hash#reject has its own definition, so this needs one too.
+  def compact_blank #:nodoc:
+    reject { |_k, v| v.blank? }
+  end
+
+  # Removes all blank values from the +Hash+ in place and returns self.
+  # Uses Object#blank? for determining if a value is blank.
+  #
+  #    h = { a: "", b: 1, c: nil, d: [], e: false, f: true }
+  #    h.compact_blank!
+  #    # => { b: 1, f: true }
+  def compact_blank!
+    # use delete_if rather than reject! because it always returns self even if nothing changed
+    delete_if { |_k, v| v.blank? }
+  end
 end
 
 class Range #:nodoc:
@@ -185,4 +220,15 @@ class Array #:nodoc:
       super
     end
   end
+
+  # Removes all blank elements from the +Array+ in place and returns self.
+  # Uses Object#blank? for determining if an item is blank.
+  #
+  #    a = [1, "", nil, 2, " ", [], {}, false, true]
+  #    a.compact_blank!
+  #    # =>  [1, 2, true]
+  def compact_blank!
+    # use delete_if rather than reject! because it always returns self even if nothing changed
+    delete_if(&:blank?)
+  end
 end
diff --git a/activesupport/test/core_ext/enumerable_test.rb b/activesupport/test/core_ext/enumerable_test.rb
index 381b5a1f32..a9bf4b82f4 100644
--- a/activesupport/test/core_ext/enumerable_test.rb
+++ b/activesupport/test/core_ext/enumerable_test.rb
@@ -242,4 +242,28 @@ class EnumerableTests < ActiveSupport::TestCase
     ])
     assert_equal [[5, 99], [15, 0], [10, 50]], payments.pluck(:dollars, :cents)
   end
+
+  def test_compact_blank
+    values = GenericEnumerable.new([1, "", nil, 2, " ", [], {}, false, true])
+
+    assert_equal [1, 2, true], values.compact_blank
+  end
+
+  def test_array_compact_blank!
+    values = [1, "", nil, 2, " ", [], {}, false, true]
+    values.compact_blank!
+
+    assert_equal [1, 2, true], values
+  end
+
+  def test_hash_compact_blank
+    values = { a: "", b: 1, c: nil, d: [], e: false, f: true }
+    assert_equal({ b: 1, f: true }, values.compact_blank)
+  end
+
+  def test_hash_compact_blank!
+    values = { a: "", b: 1, c: nil, d: [], e: false, f: true }
+    values.compact_blank!
+    assert_equal({ b: 1, f: true }, values)
+  end
 end