How to get HTTP headers in custom Marshaller?

[tymbaca]

📚 Documentation

I want to send data from client in multipart/form-data. And I want to parse it into proto-object with custom Marshaller.

mux := runtime.NewServeMux(
	runtime.WithMarshalerOption("multipart/form-data", mymarshaller.MyMarshaller{...}),
)

But to parse multipart/form-data I need to know the boundary, which is specified inside of Content-Type header: multipart/form-data; boundary=<BOUNDARY>

Inside of NewDecoder(r io.Reader) runtime.Decoder method I get io.Reader with only request body. At the same time, in debugger I see that io.Reader's underlying byte buffer contains the whole request (with headers), but the offset is set right before the body.

Is there any options to get r io.Reader with headers?

[johanbrandhorst]

You won't be able to pass headers into the marshaler, but you can combine a custom marshaler with a forwardResponseOption as described in #4483 (comment).