diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index 452809a689ebe..31b36eedb0c4a 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -276,15 +276,14 @@ def local?
       LOCALHOST =~ remote_addr && LOCALHOST =~ remote_ip
     end
 
-    protected
-
     # Remove nils from the params hash
     def deep_munge(hash)
-      hash.each_value do |v|
+      hash.each do |k, v|
         case v
         when Array
           v.grep(Hash) { |x| deep_munge(x) }
           v.compact!
+          hash[k] = nil if v.empty?
         when Hash
           deep_munge(v)
         end
@@ -293,6 +292,8 @@ def deep_munge(hash)
       hash
     end
 
+    protected
+
     def parse_query(qs)
       deep_munge(super)
     end
diff --git a/actionpack/lib/action_dispatch/middleware/params_parser.rb b/actionpack/lib/action_dispatch/middleware/params_parser.rb
index 2c98ca03a86d1..951f28f535119 100644
--- a/actionpack/lib/action_dispatch/middleware/params_parser.rb
+++ b/actionpack/lib/action_dispatch/middleware/params_parser.rb
@@ -47,12 +47,12 @@ def parse_formatted_parameters(env)
         when Proc
           strategy.call(request.raw_post)
         when :xml_simple, :xml_node
-          data = Hash.from_xml(request.raw_post) || {}
+          data = request.deep_munge(Hash.from_xml(request.body.read) || {})
           data.with_indifferent_access
         when :yaml
           YAML.load(request.raw_post)
         when :json
-          data = ActiveSupport::JSON.decode(request.raw_post)
+          data = request.deep_munge ActiveSupport::JSON.decode(request.body)
           data = {:_json => data} unless data.is_a?(Hash)
           data.with_indifferent_access
         else
diff --git a/actionpack/test/dispatch/request/json_params_parsing_test.rb b/actionpack/test/dispatch/request/json_params_parsing_test.rb
index c0c3147e3731a..2c4a6c2147f0c 100644
--- a/actionpack/test/dispatch/request/json_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/json_params_parsing_test.rb
@@ -30,6 +30,21 @@ def teardown
     )
   end
 
+  test "nils are stripped from collections" do
+    assert_parses(
+      {"person" => nil},
+      "{\"person\":[null]}", { 'CONTENT_TYPE' => 'application/json' }
+    )
+    assert_parses(
+      {"person" => ['foo']},
+      "{\"person\":[\"foo\",null]}", { 'CONTENT_TYPE' => 'application/json' }
+    )
+    assert_parses(
+      {"person" => nil},
+      "{\"person\":[null, null]}", { 'CONTENT_TYPE' => 'application/json' }
+    )
+  end
+
   test "logs error if parsing unsuccessful" do
     with_test_routing do
       output = StringIO.new
diff --git a/actionpack/test/dispatch/request/xml_params_parsing_test.rb b/actionpack/test/dispatch/request/xml_params_parsing_test.rb
index cb68667002d96..f13b64a3c7f37 100644
--- a/actionpack/test/dispatch/request/xml_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/xml_params_parsing_test.rb
@@ -30,6 +30,23 @@ def call(env)
     assert_equal "<ok>bar</ok>", resp.body
   end
 
+  def assert_parses(expected, xml)
+    with_test_routing do
+      post "/parse", xml, default_headers
+      assert_response :ok
+      assert_equal(expected, TestController.last_request_parameters)
+    end
+  end
+
+  test "nils are stripped from collections" do
+    assert_parses(
+      {"hash" => { "person" => nil} },
+      "<hash><person type=\"array\"><person nil=\"true\"/></person></hash>")
+    assert_parses(
+      {"hash" => { "person" => ['foo']} },
+      "<hash><person type=\"array\"><person>foo</person><person nil=\"true\"/></person>\n</hash>")
+  end
+
   test "parses hash params" do
     with_test_routing do
       xml = "<person><name>David</name></person>"
diff --git a/activerecord/test/cases/relation/where_test.rb b/activerecord/test/cases/relation/where_test.rb
index 297e8653084fc..d1c3690478148 100644
--- a/activerecord/test/cases/relation/where_test.rb
+++ b/activerecord/test/cases/relation/where_test.rb
@@ -90,6 +90,12 @@ def test_where_with_blank_conditions
       [[], {}, nil, ""].each do |blank|
         assert_equal 4, Edge.where(blank).order("sink_id").to_a.size
       end
+    def test_where_with_table_name_and_empty_array
+      assert_equal 0, Post.where(:id => []).count
+    end
+
+    def test_where_with_empty_hash_and_no_foreign_key
+      assert_equal 0, Edge.where(:sink => {}).count
     end
   end
 end