timeutil: time.Duration json helper

timeutil/duration.go

@@ -0,0 +1,36 @@
+package timeutil
+
+import (
+	"encoding/json"
+	"errors"
+	"time"
+)
+
+type Duration struct {
+	time.Duration
+}
+
+func (d Duration) MarshalJSON() ([]byte, error) {
+	return json.Marshal(time.Duration(d.Duration).String())
+}
+
+func (d *Duration) UnmarshalJSON(b []byte) error {
+	var v interface{}
+	if err := json.Unmarshal(b, &v); err != nil {
+		return err
+	}
+	switch value := v.(type) {
+	case float64:
+		*d = Duration{time.Duration(value)}
+		return nil
+	case string:
+		tmp, err := time.ParseDuration(value)
+		if err != nil {
+			return err
+		}
+		*d = Duration{tmp}
+		return nil
+	default:
+		return errors.New("invalid duration")
+	}
+}

timeutil/duration_test.go

@@ -0,0 +1,22 @@
+package timeutil
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestDuration(t *testing.T) {
+	js := []byte(`{"foo": "30s"}`)
+
+	foo := struct{ Foo Duration }{}
+
+	err := json.Unmarshal(js, &foo)
+	if err != nil {
+		t.Fatalf("could not unmarshal %q: %s", js, err)
+	}
+
+	if foo.Foo.Seconds() != 30 {
+		t.Fatalf("parsed time.Duration wasn't 30 seconds: %s", foo.Foo)
+	}
+
+}