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// Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
//
// Based on gopkg.in/mgo.v2/bson by Gustavo Niemeyer
// See THIRD-PARTY-NOTICES for original license terms.
package bson
import (
"bytes"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
)
// ErrInvalidHex indicates that a hex string cannot be converted to an ObjectID.
var ErrInvalidHex = errors.New("the provided hex string is not a valid ObjectID")
// ObjectID is the BSON ObjectID type.
type ObjectID [12]byte
// NilObjectID is the zero value for ObjectID.
var NilObjectID ObjectID
// Hex returns the hex encoding of the ObjectID as a string.
func (id ObjectID) Hex() string {
return hex.EncodeToString(id[:])
}
func (id ObjectID) String() string {
return fmt.Sprintf("ObjectID(%q)", id.Hex())
}
// IsZero returns true if id is the empty ObjectID.
func (id ObjectID) IsZero() bool {
return bytes.Equal(id[:], NilObjectID[:])
}
// ObjectIDFromHex creates a new ObjectID from a hex string. It returns an error if the hex string is not a
// valid ObjectID.
func ObjectIDFromHex(s string) (ObjectID, error) {
b, err := hex.DecodeString(s)
if err != nil {
return NilObjectID, err
}
if len(b) != 12 {
return NilObjectID, ErrInvalidHex
}
var oid [12]byte
copy(oid[:], b[:])
return oid, nil
}
// MarshalJSON returns the ObjectID as a string
func (id ObjectID) MarshalJSON() ([]byte, error) {
return json.Marshal(id.Hex())
}
// UnmarshalJSON populates the byte slice with the ObjectID. If the byte slice is 24 bytes long, it
// will be populated with the hex representation of the ObjectID. If the byte slice is twelve bytes
// long, it will be populated with the BSON representation of the ObjectID. This method also accepts empty strings and
// decodes them as NilObjectID. For any other inputs, an error will be returned.
func (id *ObjectID) UnmarshalJSON(b []byte) error {
// Ignore "null" to keep parity with the standard library. Decoding a JSON null into a non-pointer ObjectID field
// will leave the field unchanged. For pointer values, encoding/json will set the pointer to nil and will not
// enter the UnmarshalJSON hook.
if string(b) == "null" {
return nil
}
var err error
switch len(b) {
case 12:
copy(id[:], b)
default:
// Extended JSON
var res interface{}
err := json.Unmarshal(b, &res)
if err != nil {
return err
}
str, ok := res.(string)
if !ok {
m, ok := res.(map[string]interface{})
if !ok {
return errors.New("not an extended JSON ObjectID")
}
oid, ok := m["$oid"]
if !ok {
return errors.New("not an extended JSON ObjectID")
}
str, ok = oid.(string)
if !ok {
return errors.New("not an extended JSON ObjectID")
}
}
// An empty string is not a valid ObjectID, but we treat it as a special value that decodes as NilObjectID.
if len(str) == 0 {
copy(id[:], NilObjectID[:])
return nil
}
if len(str) != 24 {
return fmt.Errorf("cannot unmarshal into an ObjectID, the length must be 24 but it is %d", len(str))
}
_, err = hex.Decode(id[:], []byte(str))
if err != nil {
return err
}
}
return err
}
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