Use reflection to dump context

[Steve Coffman]

Sometimes for local debugging, using reflection to dump the context is handy:

func printContextInternals(ctx interface{}, inner bool) {
    contextValues := reflect.ValueOf(ctx).Elem()
    contextKeys := reflect.TypeOf(ctx).Elem()

    if !inner {
        fmt.Printf("\nFields for %s.%s\n", contextKeys.PkgPath(), contextKeys.Name())
    }

    if contextKeys.Kind() == reflect.Struct {
        for i := 0; i < contextValues.NumField(); i++ {
            reflectValue := contextValues.Field(i)
            reflectValue = reflect.NewAt(reflectValue.Type(), unsafe.Pointer(reflectValue.UnsafeAddr())).Elem()

            reflectField := contextKeys.Field(i)

            if reflectField.Name == "Context" {
                printContextInternals(reflectValue.Interface(), true)
            } else {
                fmt.Printf("field name: %+v\n", reflectField.Name)
                fmt.Printf("value: %+v\n", reflectValue.Interface())
            }
        }
    } else {
        fmt.Printf("context is empty (int)\n")
    }
}

Thanks for putting all your examples in one central place!