Rust 如何正确导入带有：：nested：：json依赖项的serde_

我正试图使用serde_中概述的设置和这里的文档将嵌套的json反序列化到我的结构中：

尝试几次后，Cargo.toml文件如下所示：

[dependencies]
serde = { version = "1.0", features = ["derive"] }
//serde_with = { version = "1.4.0", features = ["..."] } // this doesn't work even though that's what the serde_with README calls for
serde_with = { version = "1.4.0", optional = true }
serde_json = "1.0"

尝试上述操作时，会出现如下错误：

#[serde(default, rename(deserialize = "Plan"), with="serde_with::json::nested")]
                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^ use of undeclared type or module `serde_with`

---

我做错了什么？

在您的示例中，serde_模块不是可选的，必须提供json功能

替换

serde_with={version=1.4.0，optional=true}

与

serde_with={version=1.4.0，features=[json]}

完整示例：

货舱

[dependencies]
serde = { version = "1.0" }
serde_json = "1.0"
serde_derive = "1.0"
serde_with = { version = "1.4.0", features = ["json"]}

梅因

#[macro_use]
extern crate serde_derive;
extern crate serde;
extern crate serde_json;

#[derive(Deserialize, Serialize)]
struct A {
    #[serde(with = "serde_with::json::nested")]
    other_struct: B,
}

#[derive(Deserialize, Serialize)]
struct B {
    value: usize,
}

fn main() {
    let v: A = serde_json::from_str(r#"{"other_struct":"{\"value\":5}"}"#).unwrap();
    assert_eq!(5, v.other_struct.value);
    let x = A {
        other_struct: B { value: 10 },
    };
    assert_eq!(r#"{"other_struct":"{\"value\":10}"}"#, serde_json::to_string(&x).unwrap());
}