Resync

README.md

@@ -17,6 +17,8 @@ In Go, variables declared without an explicit initial value are given their zero
 
 ## Marshalling/Unmarshalling JSON
 
+**Note:** v0.6.0 introduces a potential breaking change to anyone depending on marshalling non-present values to their zero values instead of null. See: [#9](https://github.com/markphelps/optional/pull/9) for more context.
+
 Option types also marshal to/from JSON as you would expect:
 
 ### Marshalling
@@ -165,3 +167,7 @@ See [example_test.go](example_test.go) and the [documentation](http://godoc.org/
 1. Commit your changes (`git commit -am 'Add some feature'`)
 1. Push to the branch (`git push origin my-new-feature`)
 1. Create a new Pull Request
+
+### Golden Files
+
+If changing the API you may need to update the [golden files](https://medium.com/soon-london/testing-with-golden-files-in-go-7fccc71c43d3) for your tests to pass by running `go test ./cmd/optional/... -update`.

cmd/optional/main.go

@@ -183,11 +183,16 @@ func ({{ .VariableName }} {{ .OutputName }}) MarshalJSON() ([]byte, error) {
 	if {{ .VariableName }}.Present() {
 		return json.Marshal({{ .VariableName }}.value)
 	}
-	var zero {{ .TypeName }}
-	return json.Marshal(zero)
+	return json.Marshal(nil)
 }
 
 func ({{ .VariableName }} *{{ .OutputName }}) UnmarshalJSON(data []byte) error {
+
+	if string(data) == "null" {
+		{{ .VariableName }}.value = nil
+		return nil
+	}
+
 	var value {{ .TypeName }}
 
 	if err := json.Unmarshal(data, &value); err != nil {

example_test.go

@@ -99,7 +99,8 @@ func Example_set() {
 
 func Example_marshalJSON() {
 	type example struct {
-		Field *optional.String `json:"field,omitempty"`
+		Field    *optional.String `json:"field,omitempty"`
+		FieldTwo *optional.String `json:"field_two"`
 	}
 
 	var values = []optional.String{
@@ -110,28 +111,35 @@ func Example_marshalJSON() {
 
 	for _, v := range values {
 		out, _ := json.Marshal(&example{
-			Field: &v,
+			Field:    &v,
+			FieldTwo: &v,
 		})
 		fmt.Println(string(out))
 	}
 
+	out, _ := json.Marshal(&example{})
+	fmt.Println(string(out))
+
 	// Output:
-	// {"field":"foo"}
-	// {"field":""}
-	// {"field":"bar"}
+	// {"field":"foo","field_two":"foo"}
+	// {"field":"","field_two":""}
+	// {"field":"bar","field_two":"bar"}
+	// {"field_two":null}
 }
 
 func Example_unmarshalJSON() {
 	var values = []string{
-		`{"field":"foo"}`,
-		`{"field":""}`,
-		`{"field":"bar"}`,
+		`{"field":"foo","field_two":"foo"}`,
+		`{"field":"","field_two":""}`,
+		`{"field":"null","field_two":"null"}`,
+		`{"field":"bar","field_two":"bar"}`,
 		"{}",
 	}
 
 	for _, v := range values {
 		var o = &struct {
-			Field optional.String `json:"field,omitempty"`
+			Field    optional.String `json:"field,omitempty"`
+			FieldTwo optional.String `json:"field_two"`
 		}{}
 
 		if err := json.Unmarshal([]byte(v), o); err != nil {
@@ -141,10 +149,18 @@ func Example_unmarshalJSON() {
 		o.Field.If(func(s string) {
 			fmt.Println(s)
 		})
+
+		o.FieldTwo.If(func(s string) {
+			fmt.Println(s)
+		})
 	}
 
 	// Output:
 	// foo
+	// foo
+	//
+
 	//
 	// bar
+	// bar
 }