Function Example_formatText

reflect/protorange/example_test.go:107–228

Implement a basic text formatter by ranging through all populated values in a message in depth-first order.

()

// Implement a basic text formatter by ranging through all populated values
// in a message in depth-first order.
func Example_formatText() {
	m := &newspb.Article{
		Author:  "Brad Fitzpatrick",
		Date:    timestamppb.New(time.Date(2018, time.February, 16, 0, 0, 0, 0, time.UTC)),
		Title:   "Go 1.10 is released",
		Content: "Happy Friday, happy weekend! Today the Go team is happy to announce the release of Go 1.10...",
		Status:  newspb.Article_PUBLISHED,
		Tags:    []string{"go1.10", "release"},
		Attachments: []*anypb.Any{{
			TypeUrl: "google.golang.org.KeyValueAttachment",
			Value: mustMarshal(&newspb.KeyValueAttachment{
				Name: "checksums.txt",
				Data: map[string]string{
					"go1.10.src.tar.gz":         "07cbb9d0091b846c6aea40bf5bc0cea7",
					"go1.10.darwin-amd64.pkg":   "cbb38bb6ff6ea86279e01745984445bf",
					"go1.10.linux-amd64.tar.gz": "6b3d0e4a5c77352cf4275573817f7566",
					"go1.10.windows-amd64.msi":  "57bda02030f58f5d2bf71943e1390123",
				},
			}),
		}},
	}

	// Print a message in a humanly readable format.
	var indent []byte
	protorange.Options{
		Stable: true,
	}.Range(m.ProtoReflect(),
		func(p protopath.Values) error {
			// Print the key.
			var fd protoreflect.FieldDescriptor
			last := p.Index(-1)
			beforeLast := p.Index(-2)
			switch last.Step.Kind() {
			case protopath.FieldAccessStep:
				fd = last.Step.FieldDescriptor()
				fmt.Printf("%s%s: ", indent, fd.Name())
			case protopath.ListIndexStep:
				fd = beforeLast.Step.FieldDescriptor() // lists always appear in the context of a repeated field
				fmt.Printf("%s%d: ", indent, last.Step.ListIndex())
			case protopath.MapIndexStep:
				fd = beforeLast.Step.FieldDescriptor() // maps always appear in the context of a repeated field
				fmt.Printf("%s%v: ", indent, last.Step.MapIndex().Interface())
			case protopath.AnyExpandStep:
				fmt.Printf("%s[%v]: ", indent, last.Value.Message().Descriptor().FullName())
			case protopath.UnknownAccessStep:
				fmt.Printf("%s?: ", indent)
			}

			// Starting printing the value.
			switch v := last.Value.Interface().(type) {
			case protoreflect.Message:
				fmt.Printf("{\n")
				indent = append(indent, '\t')
			case protoreflect.List:
				fmt.Printf("[\n")
				indent = append(indent, '\t')
			case protoreflect.Map:
				fmt.Printf("{\n")