refactor: common ifaces

interfaces/12-marshaler/timestamp.go

@@ -0,0 +1,57 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"strconv"
+	"time"
+)
+
+type timestamp struct {
+	time.Time
+}
+
+func (ts timestamp) String() string {
+	if ts.IsZero() {
+		return "unknown"
+	}
+
+	// Mon Jan 2 15:04:05 -0700 MST 2006
+	const layout = "2006/01"
+	return ts.Format(layout)
+}
+
+// timestamp knows how to decode itself from json.
+// UnmarshalJSON is an implementation of the json.Unmarshaler interface.
+// json.Unmarshal and json.Decode call this method.
+func (ts *timestamp) UnmarshalJSON(data []byte) error {
+	*ts = toTimestamp(string(data))
+	return nil
+}
+
+// timestamp knows how to encode itself to json.
+// MarshalJSON is an implementation of the json.Marshaler interface.
+// json.Marshal and json.Encode call this method.
+func (ts timestamp) MarshalJSON() (out []byte, err error) {
+	// return ts.Time.MarshalJSON()
+	return strconv.AppendInt(out, ts.Unix(), 10), nil
+}
+
+func toTimestamp(v interface{}) (ts timestamp) {
+	var t int
+
+	switch v := v.(type) {
+	case int:
+		t = v
+	case string:
+		t, _ = strconv.Atoi(v)
+	}
+
+	ts.Time = time.Unix(int64(t), 0)
+	return ts
+}