Add embedded field support to dynamic.Marshal. (#1001)

This commit fixes a bug in dynamic.Marshal where embedded fields
were not dealt with correctly.

Signed-off-by: Eric Chlebek <eric@sensu.io>

Author: echlebek

CHANGELOG.md

@@ -26,6 +26,9 @@ in `sensuctl` with optional timezone. Stores the field as unix epoch time.
 ### Fixed
  - Fixed required flags in `sensuctl` so requirements are enforced.
 
+### Fixed
+- Add support for embedded fields to dynamic.Marshal.
+
 ## [2.0.0-alpha.16] - 2018-02-07
 ### Added
 - Add an e2e test for proxy check requests.

types/dynamic/encoding.go

@@ -150,6 +150,21 @@ func getJSONFields(v reflect.Value, addressOfAttrs *byte) map[string]structField
 				continue
 			}
 		}
+		// if the field is embedded, flatten it out
+		if sf.Field.Anonymous {
+			var attrAddr *byte
+			if x, ok := sf.Value.Interface().(AttrGetter); ok {
+				attrs := x.GetExtendedAttributes()
+				if len(attrs) > 0 {
+					attrAddr = &attrs[0]
+				}
+			}
+			fields := getJSONFields(sf.Value, attrAddr)
+			for k, v := range fields {
+				result[k] = v
+			}
+			continue
+		}
 		// sf is a valid JSON field.
 		result[sf.JSONName] = sf
 	}

types/dynamic/encoding_test.go

@@ -147,3 +147,44 @@ func TestGetJSONStructField(t *testing.T) {
 	assert.Equal("validEmpty", field.JSONName)
 	assert.Equal(false, field.OmitEmpty)
 }
+
+type Embedded struct {
+	Bar   string `json:"bar"`
+	Attrs []byte `json:"-"`
+}
+
+func (e *Embedded) GetExtendedAttributes() []byte {
+	return e.Attrs
+}
+
+func (e *Embedded) SetExtendedAttributes(b []byte) {
+	e.Attrs = b
+}
+
+type EmbeddedTest struct {
+	Foo string `json:"foo"`
+	Embedded
+	Baz string `json:"baz"`
+}
+
+func TestMarshalUnmarshalEmbedded(t *testing.T) {
+	test := &EmbeddedTest{
+		Foo: "foo",
+		Embedded: Embedded{
+			Bar: "bar",
+		},
+		Baz: "baz",
+	}
+
+	require.NoError(t, SetField(test, "extended", true))
+
+	b, err := Marshal(test)
+	require.NoError(t, err)
+
+	assert.JSONEq(t, `{"bar":"bar","baz":"baz","foo":"foo","extended":true}`, string(b))
+
+	var result EmbeddedTest
+	require.NoError(t, Unmarshal(b, &result))
+
+	require.Equal(t, test, &result)
+}