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null.go (2461B)

      1 // Copyright 2021 Google Inc.  All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 package uuid
      6 
      7 import (
      8 	"bytes"
      9 	"database/sql/driver"
     10 	"encoding/json"
     11 	"fmt"
     12 )
     13 
     14 var jsonNull = []byte("null")
     15 
     16 // NullUUID represents a UUID that may be null.
     17 // NullUUID implements the SQL driver.Scanner interface so
     18 // it can be used as a scan destination:
     19 //
     20 //  var u uuid.NullUUID
     21 //  err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&u)
     22 //  ...
     23 //  if u.Valid {
     24 //     // use u.UUID
     25 //  } else {
     26 //     // NULL value
     27 //  }
     28 //
     29 type NullUUID struct {
     30 	UUID  UUID
     31 	Valid bool // Valid is true if UUID is not NULL
     32 }
     33 
     34 // Scan implements the SQL driver.Scanner interface.
     35 func (nu *NullUUID) Scan(value interface{}) error {
     36 	if value == nil {
     37 		nu.UUID, nu.Valid = Nil, false
     38 		return nil
     39 	}
     40 
     41 	err := nu.UUID.Scan(value)
     42 	if err != nil {
     43 		nu.Valid = false
     44 		return err
     45 	}
     46 
     47 	nu.Valid = true
     48 	return nil
     49 }
     50 
     51 // Value implements the driver Valuer interface.
     52 func (nu NullUUID) Value() (driver.Value, error) {
     53 	if !nu.Valid {
     54 		return nil, nil
     55 	}
     56 	// Delegate to UUID Value function
     57 	return nu.UUID.Value()
     58 }
     59 
     60 // MarshalBinary implements encoding.BinaryMarshaler.
     61 func (nu NullUUID) MarshalBinary() ([]byte, error) {
     62 	if nu.Valid {
     63 		return nu.UUID[:], nil
     64 	}
     65 
     66 	return []byte(nil), nil
     67 }
     68 
     69 // UnmarshalBinary implements encoding.BinaryUnmarshaler.
     70 func (nu *NullUUID) UnmarshalBinary(data []byte) error {
     71 	if len(data) != 16 {
     72 		return fmt.Errorf("invalid UUID (got %d bytes)", len(data))
     73 	}
     74 	copy(nu.UUID[:], data)
     75 	nu.Valid = true
     76 	return nil
     77 }
     78 
     79 // MarshalText implements encoding.TextMarshaler.
     80 func (nu NullUUID) MarshalText() ([]byte, error) {
     81 	if nu.Valid {
     82 		return nu.UUID.MarshalText()
     83 	}
     84 
     85 	return jsonNull, nil
     86 }
     87 
     88 // UnmarshalText implements encoding.TextUnmarshaler.
     89 func (nu *NullUUID) UnmarshalText(data []byte) error {
     90 	id, err := ParseBytes(data)
     91 	if err != nil {
     92 		nu.Valid = false
     93 		return err
     94 	}
     95 	nu.UUID = id
     96 	nu.Valid = true
     97 	return nil
     98 }
     99 
    100 // MarshalJSON implements json.Marshaler.
    101 func (nu NullUUID) MarshalJSON() ([]byte, error) {
    102 	if nu.Valid {
    103 		return json.Marshal(nu.UUID)
    104 	}
    105 
    106 	return jsonNull, nil
    107 }
    108 
    109 // UnmarshalJSON implements json.Unmarshaler.
    110 func (nu *NullUUID) UnmarshalJSON(data []byte) error {
    111 	if bytes.Equal(data, jsonNull) {
    112 		*nu = NullUUID{}
    113 		return nil // valid null UUID
    114 	}
    115 	err := json.Unmarshal(data, &nu.UUID)
    116 	nu.Valid = err == nil
    117 	return err
    118 }