helpers.go

package middleware

import (
	"context"

	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
)

type (
	// WrappedServerStream overrides the Context() method of the
	// grpc.ServerStream interface.
	WrappedServerStream struct {
		grpc.ServerStream
		ctx context.Context
	}
)

// NewWrappedServerStream returns a new wrapped grpc ServerStream.
func NewWrappedServerStream(ctx context.Context, ss grpc.ServerStream) *WrappedServerStream {
	return &WrappedServerStream{
		ctx:          ctx,
		ServerStream: ss,
	}
}

// Context returns the context for the server stream.
func (w *WrappedServerStream) Context() context.Context {
	return w.ctx
}

// MetadataValue returns the first value for the given metadata key if
// key exists, else returns an empty string.
func MetadataValue(md metadata.MD, key string) string {
	if vals := md.Get(key); len(vals) > 0 {
		return vals[0]
	}
	return ""
}