feat(uuid): Added support for NullUUID (#76)

2 files changed, 358 insertions, 0 deletions

diff --git a/null.go b/null.go
new file mode 100644
index 0000000..95bb632
--- /dev/null
+++ b/null.go
@@ -0,0 +1,120 @@
+// Copyright 2021 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package uuid
+
+import (
+	"bytes"
+	"database/sql/driver"
+	"encoding/json"
+	"fmt"
+)
+
+// NullUUID represents a UUID that may be null.
+// NullUUID implements the Scanner interface so
+// it can be used as a scan destination:
+//
+//  var u uuid.NullUUID
+//  err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&u)
+//  ...
+//  if u.Valid {
+//     // use u.UUID
+//  } else {
+//     // NULL value
+//  }
+//
+type NullUUID struct {
+	UUID  UUID
+	Valid bool // Valid is true if UUID is not NULL
+}
+
+// Scan implements the Scanner interface.
+func (nu *NullUUID) Scan(value interface{}) error {
+	if value == nil {
+		nu.UUID, nu.Valid = Nil, false
+		return nil
+	}
+
+	err := nu.UUID.Scan(value)
+	if err != nil {
+		nu.Valid = false
+		return err
+	}
+
+	nu.Valid = true
+	return nil
+}
+
+// Value implements the driver Valuer interface.
+func (nu NullUUID) Value() (driver.Value, error) {
+	if !nu.Valid {
+		return nil, nil
+	}
+	// Delegate to UUID Value function
+	return nu.UUID.Value()
+}
+
+// MarshalBinary implements encoding.BinaryMarshaler.
+func (nu NullUUID) MarshalBinary() ([]byte, error) {
+	if nu.Valid {
+		return nu.UUID[:], nil
+	}
+
+	return []byte(nil), nil
+}
+
+// UnmarshalBinary implements encoding.BinaryUnmarshaler.
+func (nu *NullUUID) UnmarshalBinary(data []byte) error {
+	if len(data) != 16 {
+		return fmt.Errorf("invalid UUID (got %d bytes)", len(data))
+	}
+	copy(nu.UUID[:], data)
+	nu.Valid = true
+	return nil
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (nu NullUUID) MarshalText() ([]byte, error) {
+	if nu.Valid {
+		return nu.UUID.MarshalText()
+	}
+
+	return []byte{110, 117, 108, 108}, nil
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (nu *NullUUID) UnmarshalText(data []byte) error {
+	id, err := ParseBytes(data)
+	if err != nil {
+		nu.Valid = false
+		return err
+	}
+	nu.UUID = id
+	nu.Valid = true
+	return nil
+}
+
+// MarshalJSON implements json.Marshaler.
+func (nu NullUUID) MarshalJSON() ([]byte, error) {
+	if nu.Valid {
+		return json.Marshal(nu.UUID)
+	}
+
+	return json.Marshal(nil)
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (nu *NullUUID) UnmarshalJSON(data []byte) error {
+	null := []byte{110, 117, 108, 108}
+	if bytes.Equal(data, null) {
+		return nil // valid null UUID
+	}
+
+	var u UUID
+	// tossing as we know u is valid
+	_ = json.Unmarshal(data, &u)
+	nu.Valid = true
+	nu.UUID = u
+	return nil
+}
diff --git a/null_test.go b/null_test.go
new file mode 100644
index 0000000..b1988a4
--- /dev/null
+++ b/null_test.go
@@ -0,0 +1,238 @@
+// Copyright 2021 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package uuid
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"testing"
+)
+
+func TestNullUUIDScan(t *testing.T) {
+	var u UUID
+	var nu NullUUID
+
+	uNilErr := u.Scan(nil)
+	nuNilErr := nu.Scan(nil)
+	if uNilErr != nil &&
+		nuNilErr != nil &&
+		uNilErr.Error() != nuNilErr.Error() {
+		t.Errorf("expected errors to be equal, got %s, %s", uNilErr, nuNilErr)
+	}
+
+	uInvalidStringErr := u.Scan("test")
+	nuInvalidStringErr := nu.Scan("test")
+	if uInvalidStringErr != nil &&
+		nuInvalidStringErr != nil &&
+		uInvalidStringErr.Error() != nuInvalidStringErr.Error() {
+		t.Errorf("expected errors to be equal, got %s, %s", uInvalidStringErr, nuInvalidStringErr)
+	}
+
+	valid := "12345678-abcd-1234-abcd-0123456789ab"
+	uValidErr := u.Scan(valid)
+	nuValidErr := nu.Scan(valid)
+	if uValidErr != nuValidErr {
+		t.Errorf("expected errors to be equal, got %s, %s", uValidErr, nuValidErr)
+	}
+}
+
+func TestNullUUIDValue(t *testing.T) {
+	var u UUID
+	var nu NullUUID
+
+	nuValue, nuErr := nu.Value()
+	if nuErr != nil {
+		t.Errorf("expected nil err, got err %s", nuErr)
+	}
+	if nuValue != nil {
+		t.Errorf("expected nil value, got non-nil %s", nuValue)
+	}
+
+	u = MustParse("12345678-abcd-1234-abcd-0123456789ab")
+	nu = NullUUID{
+		UUID:  MustParse("12345678-abcd-1234-abcd-0123456789ab"),
+		Valid: true,
+	}
+
+	uValue, uErr := u.Value()
+	nuValue, nuErr = nu.Value()
+	if uErr != nil {
+		t.Errorf("expected nil err, got err %s", uErr)
+	}
+	if nuErr != nil {
+		t.Errorf("expected nil err, got err %s", nuErr)
+	}
+	if uValue != nuValue {
+		t.Errorf("expected uuid %s and nulluuid %s to be equal ", uValue, nuValue)
+	}
+}
+
+func TestNullUUIDMarshalText(t *testing.T) {
+	tests := []struct {
+		nullUUID NullUUID
+	}{
+		{
+			nullUUID: NullUUID{},
+		},
+		{
+			nullUUID: NullUUID{
+				UUID:  MustParse("12345678-abcd-1234-abcd-0123456789ab"),
+				Valid: true,
+			},
+		},
+	}
+	for _, test := range tests {
+		var uText []byte
+		var uErr error
+		nuText, nuErr := test.nullUUID.MarshalText()
+		if test.nullUUID.Valid {
+			uText, uErr = test.nullUUID.UUID.MarshalText()
+		} else {
+			uText = []byte("null")
+		}
+		if nuErr != uErr {
+			t.Errorf("expected error %e, got %e", nuErr, uErr)
+		}
+		if !bytes.Equal(nuText, uText) {
+			t.Errorf("expected text data %s, got %s", string(nuText), string(uText))
+		}
+	}
+}
+
+func TestNullUUIDUnmarshalText(t *testing.T) {
+	tests := []struct {
+		nullUUID NullUUID
+	}{
+		{
+			nullUUID: NullUUID{},
+		},
+		{
+			nullUUID: NullUUID{
+				UUID:  MustParse("12345678-abcd-1234-abcd-0123456789ab"),
+				Valid: true,
+			},
+		},
+	}
+	for _, test := range tests {
+		var uText []byte
+		var uErr error
+		nuText, nuErr := test.nullUUID.MarshalText()
+		if test.nullUUID.Valid {
+			uText, uErr = test.nullUUID.UUID.MarshalText()
+		} else {
+			uText = []byte("null")
+		}
+		if nuErr != uErr {
+			t.Errorf("expected error %e, got %e", nuErr, uErr)
+		}
+		if !bytes.Equal(nuText, uText) {
+			t.Errorf("expected text data %s, got %s", string(nuText), string(uText))
+		}
+	}
+}
+
+func TestNullUUIDMarshalBinary(t *testing.T) {
+	tests := []struct {
+		nullUUID NullUUID
+	}{
+		{
+			nullUUID: NullUUID{},
+		},
+		{
+			nullUUID: NullUUID{
+				UUID:  MustParse("12345678-abcd-1234-abcd-0123456789ab"),
+				Valid: true,
+			},
+		},
+	}
+	for _, test := range tests {
+		var uBinary []byte
+		var uErr error
+		nuBinary, nuErr := test.nullUUID.MarshalBinary()
+		if test.nullUUID.Valid {
+			uBinary, uErr = test.nullUUID.UUID.MarshalBinary()
+		} else {
+			uBinary = []byte(nil)
+		}
+		if nuErr != uErr {
+			t.Errorf("expected error %e, got %e", nuErr, uErr)
+		}
+		if !bytes.Equal(nuBinary, uBinary) {
+			t.Errorf("expected binary data %s, got %s", string(nuBinary), string(uBinary))
+		}
+	}
+}
+
+func TestNullUUIDMarshalJSON(t *testing.T) {
+	jsonNull, _ := json.Marshal(nil)
+	jsonUUID, _ := json.Marshal(MustParse("12345678-abcd-1234-abcd-0123456789ab"))
+	tests := []struct {
+		nullUUID    NullUUID
+		expected    []byte
+		expectedErr error
+	}{
+		{
+			nullUUID:    NullUUID{},
+			expected:    jsonNull,
+			expectedErr: nil,
+		},
+		{
+			nullUUID: NullUUID{
+				UUID:  MustParse(string(jsonUUID)),
+				Valid: true,
+			},
+			expected:    []byte(`"12345678-abcd-1234-abcd-0123456789ab"`),
+			expectedErr: nil,
+		},
+	}
+	for _, test := range tests {
+		data, err := json.Marshal(&test.nullUUID)
+		if err != test.expectedErr {
+			t.Errorf("expected error %e, got %e", test.expectedErr, err)
+		}
+		if !bytes.Equal(data, test.expected) {
+			t.Errorf("expected json data %s, got %s", string(test.expected), string(data))
+		}
+	}
+}
+
+func TestNullUUIDUnmarshalJSON(t *testing.T) {
+	jsonNull, _ := json.Marshal(nil)
+	jsonUUID, _ := json.Marshal(MustParse("12345678-abcd-1234-abcd-0123456789ab"))
+
+	var nu NullUUID
+	err := json.Unmarshal(jsonNull, &nu)
+	if err != nil || nu.Valid {
+		t.Errorf("expected nil when unmarshaling null, got %s", err)
+	}
+	err = json.Unmarshal(jsonUUID, &nu)
+	if err != nil || !nu.Valid {
+		t.Errorf("expected nil when unmarshaling null, got %s", err)
+	}
+}
+
+func TestConformance(t *testing.T) {
+	input := []byte(`"12345678-abcd-1234-abcd-0123456789ab"`)
+	var n NullUUID
+	var u UUID
+
+	err := json.Unmarshal(input, &n)
+	fmt.Printf("Unmarshal NullUUID: %+v %v\n", n, err)
+	err = json.Unmarshal(input, &u)
+	fmt.Printf("Unmarshal UUID: %+v %v\n", u, err)
+
+	n = NullUUID{}
+	data, err := json.Marshal(&n)
+	fmt.Printf("Marshal Empty NullUUID %s %v\n", data, err)
+
+	n.Valid = true
+	n.UUID = u
+	data, err = json.Marshal(&n)
+	fmt.Printf("Marshal Filled NullUUID %s %v\n", data, err)
+
+	data, err = json.Marshal(&u)
+	fmt.Printf("Marshal UUID: %s %v\n", data, err)
+}