defaults.go

Documentation: github.com/golang/protobuf/proto

     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
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