feat: implement an JSON and Text marshal and unmarshal

objectid.go

@@ -6,9 +6,11 @@ import (
 	"crypto/rand"
 	"encoding/binary"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -92,6 +94,40 @@ func (id ID) Count() uint32 {
 // IsZero returns true if the ObjectID is the Nil value.
 func (id ID) IsZero() bool { return id == Nil }
 
+// MarshalText implements the encoding.TextMarshaler interface.
+// This is useful when using the ID as a map key during JSON marshalling.
+func (id ID) MarshalText() ([]byte, error) {
+	return []byte(id.String()), nil
+}
+
+// UnmarshalText implements the encoding.TextUnmarshaler interface.
+// This is useful when using the ID as a map key during JSON unmarshalling.
+func (id *ID) UnmarshalText(b []byte) error {
+	decoded, err := Decode(string(b))
+	if err != nil {
+		return err
+	}
+	*id = decoded
+	return nil
+}
+
+// MarshalJSON implements the json.Marshaler interface.
+func (id ID) MarshalJSON() ([]byte, error) {
+	return json.Marshal(id.String())
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (id *ID) UnmarshalJSON(data []byte) error {
+	// remove the surrounding quotes from the JSON string
+	str := strings.Trim(string(data), "\"")
+	decoded, err := Decode(str)
+	if err != nil {
+		return err
+	}
+	*id = decoded
+	return nil
+}
+
 // Decode decodes the string representation and returns the corresponding ID.
 func Decode(s string) (ID, error) {
 	if len(s) != 24 {

objectid_test.go

@@ -1,6 +1,8 @@
 package objectid_test
 
 import (
+	"bytes"
+	"encoding/json"
 	"github.com/pkg-id/objectid"
 	"strings"
 	"testing"
@@ -75,3 +77,98 @@ func TestDecode(t *testing.T) {
 		t.Fatalf("expec id must be a zero value")
 	}
 }
+
+func TestID_MarshalText(t *testing.T) {
+	// Test valid input
+	id := objectid.New()
+	expectedOutput := []byte(id.String())
+	output, err := id.MarshalText()
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if !bytes.Equal(expectedOutput, output) {
+		t.Errorf("Expected %v but got %v", expectedOutput, output)
+	}
+
+	// Test invalid input
+	id = objectid.ID{}
+	expectedOutput = []byte(id.String())
+	output, err = id.MarshalText()
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if !bytes.Equal(expectedOutput, output) {
+		t.Errorf("Expected %v but got %v", expectedOutput, output)
+	}
+}
+
+func TestID_UnmarshalText(t *testing.T) {
+	// Test valid input
+	id := objectid.New()
+	b := []byte(id.String())
+	expectedOutput := &id
+	err := expectedOutput.UnmarshalText(b)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if *expectedOutput != id {
+		t.Errorf("Expected %v but got %v", id, *expectedOutput)
+	}
+
+	// Test invalid input
+	b = []byte("invalid")
+	expectedOutput = &id
+	err = expectedOutput.UnmarshalText(b)
+	if err == nil {
+		t.Errorf("Expected error but got nil")
+	}
+}
+
+func TestID_MarshalJSON(t *testing.T) {
+	// Test valid input
+	id := objectid.New()
+	expectedOutput, err := json.Marshal(id)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	output, err := id.MarshalJSON()
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if !bytes.Equal(expectedOutput, output) {
+		t.Errorf("Expected %v but got %v", expectedOutput, output)
+	}
+
+	// Test invalid input
+	id = objectid.ID{}
+	expectedOutput, err = json.Marshal(id)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	output, err = id.MarshalJSON()
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if !bytes.Equal(expectedOutput, output) {
+		t.Errorf("Expected %v but got %v", expectedOutput, output)
+	}
+}
+
+func TestID_UnmarshalJSON(t *testing.T) {
+	type Data struct {
+		ID objectid.ID `json:"id"`
+	}
+
+	rawJSON := `{"id":"640c5fe5d243553cda8dde1b"}`
+
+	var obj Data
+	err := json.Unmarshal([]byte(rawJSON), &obj)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	expectedID := "640c5fe5d243553cda8dde1b"
+	if obj.ID.String() != expectedID {
+		t.Errorf("Unexpected ID value: got %s, expected %s", obj.ID, expectedID)
+	}
+}