Microsoft bond c++ runtime deserialization using runtime schema

Question

I could not find anything useful in their docs or examples :( They have docs of how to deserialize schema, and then how to traverse it - that works great. They have also two examples:

1. how to use bond::bonded<void> with runtime schema to convert binary to json
2. how to use bond::bonded<void> with runtime schema and MapTo to parse data into some custom ViewStruct

What I need is: to traverse the bond:bonded<void> to extract fields from it.

In protobuf you have field descriptors (created using FinFieldByName) and then you use them in runtime methods msg->getString, msg->getInt32 to get the typed value.

Answer 1

There's nothing built in that allows you to traverse a bonded<void> and inspect its fields. If you need to do that generically, you'll need to implement a custom transform and then use bond::Apply() to apply the transform to a bonded<void> constructed from a reader and a runtime schema. See in particular the transform and access_control examples for how to start writing a transform.

Bond needs this level of indirection compared to Protocol Buffers because Bond supports pluggable encoding protocols. If you know that you will only have to process a specific protocol, you could use that protocol's reader type with the runtime schema to walk the fields in the payload. See Microsoft Bond deserialization without knowing underlying schema for a C# example of the core of this algorithm.