Fix to_query with empty arrays too

2 files changed, 8 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/core_ext/object/to_query.rb b/activesupport/lib/active_support/core_ext/object/to_query.rb
index 5d5fcf00e0..37352fa608 100644
--- a/activesupport/lib/active_support/core_ext/object/to_query.rb
+++ b/activesupport/lib/active_support/core_ext/object/to_query.rb
@@ -18,7 +18,12 @@ class Array
   #   ['Rails', 'coding'].to_query('hobbies') # => "hobbies%5B%5D=Rails&hobbies%5B%5D=coding"
   def to_query(key)
     prefix = "#{key}[]"
-    collect { |value| value.to_query(prefix) }.join '&'
+
+    if empty?
+      nil.to_query(prefix)
+    else
+      collect { |value| value.to_query(prefix) }.join '&'
+    end
   end
 end
 
diff --git a/activesupport/test/core_ext/object/to_query_test.rb b/activesupport/test/core_ext/object/to_query_test.rb
index a892471e0f..f887a9e613 100644
--- a/activesupport/test/core_ext/object/to_query_test.rb
+++ b/activesupport/test/core_ext/object/to_query_test.rb
@@ -55,6 +55,8 @@ class ToQueryTest < ActiveSupport::TestCase
       { p: 12, b: { c: false, e: nil, f: '' } }
     assert_query_equal 'b%5Bc%5D=3&b%5Bf%5D=&b%5Bk%5D=',
       { b: { c: 3, k: {}, f: '' } }
+    assert_query_equal 'a%5B%5D=&b=3',
+      {a: [], b: 3}
   end
 
   private