Crate js_option[][src]

This crate provides a type JsOption that is very similar to the standard library’s Option type except that it has three variants:

  • Some(value): Like Option::Some
  • Null: Explicitly not some value
  • Undefined: Implicitly not some value

This type can be useful when you want to deserialize JSON to a Rust struct and not loose information: A regular Option deserializes to None from both an explicit null or a missing field (this is due to special casing of Option in the Deserialize and Serialize derive macros, for other types a missing field will make deserialization fail unless there is a #[serde(skip)], #[serde(skip_deserializing)] or #[serde(default)] attribute).


use js_option::JsOption;
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize)]
struct MyStruct {
    #[serde(default, skip_serializing_if = "JsOption::is_undefined")]
    my_field: JsOption<String>,



An Option-like type with two data-less variants in addition to Some: Null and Undefined.