From 7b8f571756792ed2296a766c70af4ddf69082099 Mon Sep 17 00:00:00 2001
From: Ewout <e@ewout.name>
Date: Tue, 20 Feb 2018 16:58:58 +0100
Subject: Ruby JSON encoding omits zero-length repeated fields by default.

This makes it behave the same way as the other implementations.
It is also nice to always encode an empty message as {}.
---
 ruby/ext/google/protobuf_c/encode_decode.c | 4 +++-
 ruby/tests/basic.rb                        | 4 ++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/ruby/ext/google/protobuf_c/encode_decode.c b/ruby/ext/google/protobuf_c/encode_decode.c
index 12080d03..8c6ded64 100644
--- a/ruby/ext/google/protobuf_c/encode_decode.c
+++ b/ruby/ext/google/protobuf_c/encode_decode.c
@@ -963,13 +963,15 @@ static void putary(VALUE ary, const upb_fielddef *f, upb_sink *sink,
 
   if (ary == Qnil) return;
 
+  size = NUM2INT(RepeatedField_length(ary));
+  if (size == 0 && !emit_defaults) return;
+
   upb_sink_startseq(sink, getsel(f, UPB_HANDLER_STARTSEQ), &subsink);
 
   if (upb_fielddef_isprimitive(f)) {
     sel = getsel(f, upb_handlers_getprimitivehandlertype(f));
   }
 
-  size = NUM2INT(RepeatedField_length(ary));
   for (int i = 0; i < size; i++) {
     void* memory = RepeatedField_index_native(ary, i);
     switch (type) {
diff --git a/ruby/tests/basic.rb b/ruby/tests/basic.rb
index ad34d53d..cadb1380 100644
--- a/ruby/tests/basic.rb
+++ b/ruby/tests/basic.rb
@@ -1259,6 +1259,10 @@ module BasicTest
       Foo.encode_json(Foo.new(bar: bar, baz: [baz1, baz2]))
     end
 
+    def test_json_empty
+      assert TestMessage.encode_json(TestMessage.new) == '{}'
+    end
+
     def test_json_emit_defaults
       # TODO: Fix JSON in JRuby version.
       return if RUBY_PLATFORM == "java"
-- 
cgit v1.2.3