Generate special

CHANGELOG.md

@@ -5,8 +5,13 @@
 - Code re-formatted with clang-format. Thanks goes to BuonOmo for
   suggesting and encouraging the use of a formatter and getting the
   effort started.
+
 - Added support for `GC.compact` on `Oj::Doc`
 
+- Fixed compatibility issue with Rails and the JSON gem that requires
+  a special case when using JSON.generate versus call `to_json` on an
+  object.
+
 ## 3.11.3 - 2021-03-09
 
 - Fixed `respond_to?` method on `Oj::EasyHash`.

ext/oj/dump.c

@@ -599,8 +599,8 @@ void oj_dump_obj_to_json(VALUE obj, Options copts, Out out) {
 void oj_dump_obj_to_json_using_params(VALUE obj, Options copts, Out out, int argc, VALUE *argv) {
     if (0 == out->buf) {
         out->buf = ALLOC_N(char, 4096);
-        out->end = out->buf + 4095 -
-                   BUFFER_EXTRA;  // 1 less than end plus extra for possible errors
+        // 1 less than end plus extra for possible errors
+        out->end       = out->buf + 4095 - BUFFER_EXTRA;
         out->allocated = true;
     }
     out->cur      = out->buf;

ext/oj/mimic_json.c

@@ -384,8 +384,14 @@ static VALUE mimic_generate_core(int argc, VALUE *argv, Options copts) {
         rb_raise(rb_eTypeError, "nil not allowed.");
     }
     */
-    oj_dump_obj_to_json_using_params(*argv, copts, &out, argc - 1, argv + 1);
+    if (1 < argc) {
+        oj_dump_obj_to_json_using_params(*argv, copts, &out, argc - 1, argv + 1);
+    } else {
+        VALUE active_hack[1];
 
+        active_hack[0] = rb_funcall(state_class, oj_new_id, 0);
+        oj_dump_obj_to_json_using_params(*argv, copts, &out, 1, active_hack);
+    }
     if (0 == out.buf) {
         rb_raise(rb_eNoMemError, "Not enough memory.");
     }
@@ -755,7 +761,7 @@ static VALUE mimic_object_to_json(int argc, VALUE *argv, VALUE self) {
     // seem to prefer the option of changing that.
     // oj_dump_obj_to_json(self, &mimic_object_to_json_options, &out);
     oj_dump_obj_to_json_using_params(self, &copts, &out, argc, argv);
-    if (0 == out.buf) {
+    if (NULL == out.buf) {
         rb_raise(rb_eNoMemError, "Not enough memory.");
     }
     rstr = rb_str_new2(out.buf);

ext/oj/oj.h

@@ -247,7 +247,7 @@ extern void oj_parse_options(VALUE ropts, Options copts);
 
 extern void oj_dump_obj_to_json(VALUE obj, Options copts, Out out);
 extern void
-            oj_dump_obj_to_json_using_params(VALUE obj, Options copts, Out out, int argc, VALUE *argv);
+oj_dump_obj_to_json_using_params(VALUE obj, Options copts, Out out, int argc, VALUE *argv);
 extern void oj_write_obj_to_file(VALUE obj, const char *path, Options copts);
 extern void oj_write_obj_to_stream(VALUE obj, VALUE stream, Options copts);
 extern void oj_dump_leaf_to_json(Leaf leaf, Options copts, Out out);