How to get protobuf enum as string?

The EnumDescriptor and EnumValueDescriptor classes can be used for this kind of manipulation, and the
the generated .pb.h and .pb.cc names are easy enough to read, so you can look through them to get details on the functions they offer.

In this particular case, the following should work (untested):

std::string requestTypeString = MyMessage_RequestType_Name(requestType);