Get message from FieldDescriptor in protobuf

问题

In protobuf (C#) I want to print all fields inside different messages and submessages. How can I get message type and send to function again (recursive walking to lowest child)? More specific: What I must do, that fieldDescriptor is send like a message? I search solution, which is change "???".

private void PrintAllReportableFieldsinMessage(Google.Protobuf.IMessage message)
{
    foreach (var fieldDescriptor in message.Descriptor.Fields.InFieldNumberOrder())
    {
        if (fieldDescriptor.FieldType == Google.Protobuf.Reflection.FieldType.Message)
        {
            PrintAllReportableFieldsinMessage(???); // What can I send here?
        }
        else
        {
            Google.Protobuf.Reflection.FieldOptions options = fieldDescriptor.GetOptions();
            if (options != null && options.GetExtension(HelloworldExtensions.Reportable))
            {
                var fieldValue = fieldDescriptor.Accessor.GetValue(message);
                var fieldName = fieldDescriptor.Name;
                Dispatcher.Invoke(() =>
                {
                    lReadableResult.Content += fieldName + ":" + fieldValue + "|";
                });
            }
        }
    }
}

回答1:

I found a solition. HasValue return false, if any values inside submessage are not set. Then I must create a new Imessage which have all default values. So then this code works for printing all field names in all messages and submessages.

private void PrintAllReportableFieldsinMessage(Google.Protobuf.IMessage message)
{
    foreach (var fieldDescriptor in message.Descriptor.Fields.InFieldNumberOrder())
    {
        if (fieldDescriptor.FieldType == Google.Protobuf.Reflection.FieldType.Message)
        {
            if (fieldDescriptor.Accessor.HasValue(message))
            {
                IMessage submessage = fieldDescriptor.Accessor.GetValue(message) as IMessage;
                PrintAllReportableFieldsinMessage(submessage);
            }
            else {
                IMessage cleanSubmessage = fieldDescriptor.MessageType.Parser.ParseFrom(ByteString.Empty);
                PrintAllReportableFieldsinMessage(cleanSubmessage);
            }
        }
        else
        {
            Google.Protobuf.Reflection.FieldOptions options = fieldDescriptor.GetOptions();
            if (options != null && options.GetExtension(HelloworldExtensions.Reportable))
            {
                var fieldValue = fieldDescriptor.Accessor.GetValue(message);
                var fieldName = fieldDescriptor.Name;
                Dispatcher.Invoke(() =>
                {
                    lReadableResult.Content += fieldName + ":" + fieldValue + "|";
                });
            }
        }
    }
}

来源：https://stackoverflow.com/questions/64391067/get-message-from-fielddescriptor-in-protobuf