Rust中TOML反序列化遇缺失字段与类型不匹配错误排查

尝试将TOML配置文件读取到自定义的Rust配置结构体时，遇到序列化错误无法定位。先后使用config-rs（crate名为config）和toml包进行反序列化，均出现错误：

• 初始错误：missing field: parent_url
• 更新TOML文件后错误：invalid type: map, expected a sequence

已知错误来自serde::deserialize，但无法确定代码问题。创建test_conf Cargo项目，复制以下文件即可复现问题。

src/main.rs #

pub mod configuration;

use toml::de::Error;
use configuration::config::Setting;
use configuration::test_model::TestConfig;

fn main() -> Result<(), Error> {

    let path = String::from("test.toml");
    // let content = std::fs::read_to_string(&path);
    // match content {
    //     Ok(s) => {
    //         let config: TestConfig = toml::from_str(&s)?;
    //     },
    //     Err(e) => {
    //         panic!("failed: {}", e);
    //     }
    // }
    let site = Setting::new(path);

    Ok(())
}

src/configuration/config.rs #

use config::{Config, File, FileFormat};
use std::string::String;
use crate::configuration::test_model::TestConfig;

pub struct Setting
{
    pub config_path: String,
    configs: TestConfig,
}

impl Setting
{
    pub fn new(config_file: String) -> Self {
        let parent = "src/configuration";
        let config_file_path = [parent, config_file.as_str()].join("/");

        let config_map: TestConfig = Setting::build_configs(config_file_path.clone());

        Setting {
            config_path: config_file_path,
            configs: config_map,
        }
    }

    // internal functions

    fn build_configs(config_path: String) -> TestConfig
    // where
    //     T: Setup,
    {
        let config_parser = Config::builder()
            .add_source(File::new(&config_path, FileFormat::Toml))
            .build();

        match config_parser {
            Ok(parser) => {
                let conf = parser.try_deserialize::<TestConfig>();
                match conf {
                    Ok(settings) => return settings,
                    Err(ce) => {
                        eprintln!("configuration parsing error: {}", ce);
                        std::process::exit(1);
                    }
                }
            }
            Err(ce) => {
                eprintln!("Building configuration parser failed: {}", ce);
                std::process::exit(1);
            }
        }
    }
}

src/configuration/test_model.rs #

use serde::{Serialize, Deserialize};
use std::vec::Vec;

#[derive(Serialize, Deserialize, Debug)]
pub struct TestConfig {
    pub parent_url: String,
    pub parent_folder: String,
    pub headers: Vec<Header>,
    pub things: Vec<Thing>,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct Header {
    pub header_name: String,
    pub header_value: String,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct Thing {
    pub base_name: String,
    pub place: String,
    pub requests: Vec<Request>,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct Request {
    pub name: String,
    pub item_name: String,
    pub payload: Payload,
}

#[derive(Serialize, Deserialize, Debug)]
#[allow(non_snake_case)]
pub struct Payload {
    pub lists: String,
    pub fields: String,
    pub hasOption: String,
    pub limit: String,
}

src/configuration/test.toml #

parent_url = "initial url"
parent_folder = "/home/some/path"
[headers]
[headers.accept]
header_name = "accept"
header_value = "application/json"
[headers.encoding]
header_name = "accept-encoding"
header_value = "gzip, deflate, br, zstd"
[headers.language]
header_name = "accept-language"
header_value = "en-GB;q=0.5"
[headers.referer]
header_name = "referer"
header_value = "www.com"
[headers.agent]
header_name = "user-agent"
header_value = "Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/127.0"
[headers.authority]
header_name = "authority"
header_value = "www.com"
[thing]
base_name = "base_url"
place = "test_folder"
[[thing.requests]]
name = "test_name_one"
item_name = "local_test_one_file.json"
[thing.requests.payload]
lists = "test"
fields = "symbol,symbolName"
hasOption = "true"
limit = "100"
[[thing.requests]]
name = "test_name_two"
item_name = "local_test_two_file.json"
[thing.requests.payload]
lists = "test"
fields = "symbol,symbolName"
hasOption = "true"
limit = "100"

src/configuration/model.rs #

pub mod config;
pub mod test_model;

Cargo.toml #

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

[[bin]]
name = "test_conf"
test = false
bench = false

[dependencies]
reqwest = { version = "0.12.5", features = ["blocking", "gzip", "json", "cookies"] }
tokio = { version = "1.38.0", features = ["full"] }
futures = { version = "0.3.30", features = ["executor"] }
reqwest_cookie_store = "0.8.0"
serde = { version = "1.0.203", features = ["derive"] }
serde_json = { version = "1.0.117" }
urlencoding = { version = "2.1.3" }
config = { version = "0.14.0", features = ["toml", "ini"]}
toml = { version = "0.8.14" }

内容的提问来源于stack exchange，提问作者stucash