1 // Copyright 2019 The Go Authors. 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 proto
6 7 import (
8 "google.golang.org/protobuf/reflect/protoreflect"
9 )
10 11 // SetDefaults sets unpopulated scalar fields to their default values.
12 // Fields within a oneof are not set even if they have a default value.
13 // SetDefaults is recursively called upon any populated message fields.
14 func SetDefaults(m Message) {
15 if m != nil {
16 setDefaults(MessageReflect(m))
17 }
18 }
19 20 func setDefaults(m protoreflect.Message) {
21 fds := m.Descriptor().Fields()
22 for i := 0; i < fds.Len(); i++ {
23 fd := fds.Get(i)
24 if !m.Has(fd) {
25 if fd.HasDefault() && fd.ContainingOneof() == nil {
26 v := fd.Default()
27 if fd.Kind() == protoreflect.BytesKind {
28 v = protoreflect.ValueOf(append([]byte(nil), v.Bytes()...)) // copy the default bytes
29 }
30 m.Set(fd, v)
31 }
32 continue
33 }
34 }
35 36 m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
37 switch {
38 // Handle singular message.
39 case fd.Cardinality() != protoreflect.Repeated:
40 if fd.Message() != nil {
41 setDefaults(m.Get(fd).Message())
42 }
43 // Handle list of messages.
44 case fd.IsList():
45 if fd.Message() != nil {
46 ls := m.Get(fd).List()
47 for i := 0; i < ls.Len(); i++ {
48 setDefaults(ls.Get(i).Message())
49 }
50 }
51 // Handle map of messages.
52 case fd.IsMap():
53 if fd.MapValue().Message() != nil {
54 ms := m.Get(fd).Map()
55 ms.Range(func(_ protoreflect.MapKey, v protoreflect.Value) bool {
56 setDefaults(v.Message())
57 return true
58 })
59 }
60 }
61 return true
62 })
63 }
64