使用serde-xml-rs序列化时出现LastElementNameNotAvailable错误求助

在使用serde-xml-rs解析和序列化XML的项目中，XML解析正常，但序列化时抛出LastElementNameNotAvailable错误。相关项目配置、代码及错误输出如下：

Cargo.toml配置 #

[package]
name = "serde_xml_rs_serialization_error"
version = "0.1.0"
edition = "2021"

[dependencies]
serde = { version = "1.0.164", features = ["derive"] }
serde-xml-rs = "0.6.0"

原代码（src/main.rs） #

use serde::{Deserialize, Serialize};

#[derive(Clone, Debug, Deserialize, Serialize)]
struct Types {
    #[serde(rename = "type")]
    types: Vec<Type>,
}

#[derive(Clone, Debug, Deserialize, Serialize)]
struct Type {
    name: String,
}

const XML: &str = r#"<types>
    <type name="first"/>
    <type name="second"/>
</types>"#;

fn main() {
    let types: Types = serde_xml_rs::from_str(XML).expect("Cannot parse XML.");
    dbg!(&types);
    match serde_xml_rs::to_string(&types) {
        Ok(xml) => {
            dbg!(xml);
        }
        Err(error) => {
            dbg!(error);
        }
    };
}

运行错误输出 #

cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.05s
     Running `target\debug\serde_xml_rs_serialization_error.exe`
[src\main.rs:21] &types = Types {
    types: [
        Type {
            name: "first",
        },
        Type {
            name: "second",
        },
    ],
}
[src\main.rs:27] error = Writer {
    source: LastElementNameNotAvailable,
}

原因分析 #

报错核心原因是根结构体Types未指定序列化对应的XML根元素名称。解析XML时，输入的XML有明确的根标签<types>，serde-xml-rs能正确映射到Types结构体；但序列化时，库无法自动推断根元素名称，因此抛出LastElementNameNotAvailable错误。

解决方法 #

给Types结构体添加#[serde(rename = "types")]属性，明确指定其对应的XML根元素名称：

修改后的代码 #

use serde::{Deserialize, Serialize};

#[derive(Clone, Debug, Deserialize, Serialize)]
#[serde(rename = "types")] // 新增该行指定根元素名称
struct Types {
    #[serde(rename = "type")]
    types: Vec<Type>,
}

#[derive(Clone, Debug, Deserialize, Serialize)]
struct Type {
    name: String,
}

const XML: &str = r#"<types>
    <type name="first"/>
    <type name="second"/>
</types>"#;

fn main() {
    let types: Types = serde_xml_rs::from_str(XML).expect("Cannot parse XML.");
    dbg!(&types);
    match serde_xml_rs::to_string(&types) {
        Ok(xml) => {
            dbg!(xml);
        }
        Err(error) => {
            dbg!(error);
        }
    };
}

验证结果 #

修改后运行代码，序列化会成功生成符合预期的XML：

"<types><type name=\"first\"/><type name=\"second\"/></types>"

内容的提问来源于stack exchange，提问作者user3515670