beego | performance web framework for the Go programming language | REST library

To make sure that JSON does not contain unexpected fields you can use Decoder from "encoding/json" package and it's method DisallowUnknownFields. See example here https://play.golang.org/p/bif833qxytE

Note that to json.NewDecoder takes io.Reader as an input. You can create io.Reader from []byte by using bytes.NewReader

Another topic is making sure that JSON contains all fields that are expected (OR these fields are in certain format). The answer to how make it work with "encoding/json" package is to implement custom UnmarshalJSON for the struct, can be found here. But I would not suggest using this approach for such task, because basically this is a validation of an input and I would rather use validation packages for this not to mix responsibilities. The most common one is go-playground/validator.v9 where you should look for required tag. Validation cases are discussed here.

Im answering my own question as I believe Ive found a way and it might help someone else too - apparently it was just a matter of looking harder for existing plugins. I found that this plugin : https://github.com/sergeylanzman/newrelic_beego does exactly what I needed.

If we observe the code, it the author has created 3 methods -

1. StartTransaction
2. NameTransaction
3. EndTransaction

and is inserting these as filters in the Beego environment. Under the hood the author has used the official Newrelic Go Agent (https://github.com/newrelic/go-agent) and is using Transactions to report APM data.

Here is the sample code from the plugin which registers the 3 filters -