Rust Web 全栈开发之 Web Service 中的错误处理

Rust Web 全栈开发之 Web Service 中的错误处理Web Service 中的统一错误处理Actix Web Service 自定义错误类型 -> 自定义错误转为 HTTP Response

• 数据库
  • 数据库错误
• 串行化
  • serde 错误
• I/O 操作
  • I/O 错误
• Actix-Web 库
  • Actix 错误
• 用户非法输入
  • 用户非法输入错误

Actix-Web 的错误处理

• 编程语言常用的两种错误处理方式：
  • 异常
  • 返回值（ Rust 使用这种）
• Rust 希望开发者显式的处理错误，因此，可能出错的函数返回Result 枚举类型，其定义如下：

enum Result {  Ok(T),Err(E),}

例子

use std::num::ParseIntError;fn main() {  let result = square("25");  println!("{:?}", result);}fn square(val: &str) -> Result {  match val.parse::() {    Ok(num) => Ok(num.pow(2)),    Err(e) => Err(3),  }}

? 运算符

• 在某函数中使用 ? 运算符，该运算符尝试从 Result 中获取值：
  • 如果不成功，它就会接收 Error ，中止函数执行，并把错误传播到调用该函数的函数。

use std::num::ParseIntError;fn main() {  let result = square("25");  println!("{:?}", result);}fn square(val: &str) -> Result {  let num = val.parse::()?;  Ok(num ^ 2)}

自定义错误类型

• 创建一个自定义错误类型，它可以是多种错误类型的抽象。
• 例如：

#[derive(Debug)]pub enum MyError {  ParseError,IOError,}

Actix-Web 把错误转化为 HTTP Response

• Actix-Web 定义了一个通用的错误类型（ struct ）：actix_web::error::Error
  • 它实现了 std::error::Error 这个 trait
• 任何实现了标准库 Error trait 的类型，都可以通过 ? 运算符，转化为 Actix 的 Error 类型
• Actix 的 Error 类型会自动的转化为 HTTP Response ，返回给客户端。
• ResponseError trait ：任何实现该 trait 的错误均可转化为HTTP Response 消息。
• 内置的实现： Actix-Web 对于常见错误有内置的实现，例如：
• Rust 标准 I/O 错误
• Serde 错误
• Web 错误，例如： ProtocolError 、 Utf8Error 、 ParseError 等等
• 其它错误类型：内置实现不可用时，需要自定义实现错误到 HTTP Response 的转换

创建自定义错误处理器

1. 创建一个自定义错误类型
2. 实现 From trait ，用于把其它错误类型转化为该类型
3. 为自定义错误类型实现 ResponseError trait
4. 在 handler 里返回自定义错误类型
5. Actix 会把错误转化为 HTTP 响应

项目目录

ws on  main [✘!?] via ? 1.67.1 via ? base ➜ tree -a -I target .├── .env├── .git├── .gitignore├── Cargo.lock├── Cargo.toml├── README.md└── webservice    ├── Cargo.toml    └── src        ├── bin        │   ├── server1.rs        │   └── teacher-service.rs        ├── db_access.rs        ├── errors.rs        ├── handlers.rs        ├── main.rs        ├── models.rs        ├── routers.rs        └── state.rs40 directories, 47 filesws on  main [✘!?] via ? 1.67.1 via ? base 

webservice/src/errors.rs

use actix_web::{error, http::StatusCode, HttpResponse, Result};use serde::Serialize;use sqlx::error::Error as SQLxError;use std::fmt;#[derive(Debug, Serialize)]pub enum MyError {    DBError(String),    ActixError(String),    NotFound(String),}#[derive(Debug, Serialize)]pub struct MyErrorResponse {    error_message: String,}impl MyError {    fn error_response(&self) -> String {        match self {            MyError::DBError(msg) => {                println!("Database error occurred: {:?}", msg);                "Database error".into()            }            MyError::ActixError(msg) => {                println!("Server error occurred: {:?}", msg);                "Internal server error".into()            }            MyError::NotFound(msg) => {                println!("Not found error occurred: {:?}", msg);                msg.into()            }        }    }}impl error::ResponseError for MyError {    fn status_code(&self) -> StatusCode {        match self {            MyError::DBError(msg) | MyError::ActixError(msg) => StatusCode::INTERNAL_SERVER_ERROR,            MyError::NotFound(msg) => StatusCode::NOT_FOUND,        }    }    fn error_response(&self) -> HttpResponse {        HttpResponse::build(self.status_code()).json(MyErrorResponse {            error_message: self.error_response(),        })    }}impl fmt::Display for MyError {    fn fmt(&self, f: &mut fmt::Formatter) -> Result {        write!(f, "{}", self)    }}impl From for MyError {    fn from(err: actix_web::error::Error) -> Self {        MyError::ActixError(err.to_string())    }}impl From for MyError {    fn from(err: SQLxError) -> Self {        MyError::DBError(err.to_string())    }}

webservice/src/bin/teacher-service.rs

use actix_web::{web, App, HttpServer};use dotenv::dotenv;use sqlx::postgres::PgPoolOptions;use std::env;use std::io;use std::sync::Mutex;#[path = "../db_access.rs"]mod db_access;#[path = "../errors.rs"]mod errors;#[path = "../handlers.rs"]mod handlers;#[path = "../models.rs"]mod models;#[path = "../routers.rs"]mod routers;#[path = "../state.rs"]mod state;use routers::*;use state::AppState;#[actix_rt::main]async fn main() -> io::Result {    dotenv().ok();    let database_url = env::var("DATABASE_URL").expect("DATABASE_URL is not set.");    let db_pool = PgPoolOptions::new().connect(&database_url).await.unwrap();    let shared_data = web::Data::new(AppState {        health_check_response: "I'm Ok.".to_string(),        visit_count: Mutex::new(0),        // courses: Mutex::new(vec![]),        db: db_pool,    });    let app = move || {        App::new()            .app_data(shared_data.clone())            .configure(general_routes)            .configure(course_routes) // 路由注册    };    HttpServer::new(app).bind("127.0.0.1:3000")?.run().await}

webservice/src/db_access.rs

use super::errors::MyError;use super::models::*;use chrono::NaiveDateTime;use sqlx::postgres::PgPool;pub async fn get_courses_for_teacher_db(    pool: &PgPool,    teacher_id: i32,) -> Result<Vec, MyError> {    let rows = sqlx::query!(        r#"SELECT id, teacher_id, name, time FROM course WHERE teacher_id = $1"#,        teacher_id    )    .fetch_all(pool)    .await?;    let courses: Vec = rows        .iter()        .map(|row| Course {            id: Some(row.id),            teacher_id: row.teacher_id,            name: row.name.clone(),            time: Some(NaiveDateTime::from(row.time.unwrap())),        })        .collect();    match courses.len() {        0 => Err(MyError::NotFound("Courses not found teacher".into())),        _ => Ok(courses),    }}pub async fn get_courses_detail_db(pool: &PgPool, teacher_id: i32, course_id: i32) -> Course {    let row = sqlx::query!(        r#"SELECT id, teacher_id, name, time FROM course WHERE teacher_id = $1 and id = $2"#,        teacher_id,        course_id    )    .fetch_one(pool)    .await    .unwrap();    Course {        id: Some(row.id),        teacher_id: row.teacher_id,        name: row.name.clone(),        time: Some(NaiveDateTime::from(row.time.unwrap())),    }}pub async fn post_new_course_db(pool: &PgPool, new_course: Course) -> Course {    let row = sqlx::query!(        r#"INSERT INTO course (id, teacher_id, name) VALUES ($1, $2, $3)        RETURNING id, teacher_id, name, time"#,        new_course.id,        new_course.teacher_id,        new_course.name    )    .fetch_one(pool)    .await    .unwrap();    Course {        id: Some(row.id),        teacher_id: row.teacher_id,        name: row.name.clone(),        time: Some(NaiveDateTime::from(row.time.unwrap())),    }}

webservice/src/handlers.rs

use super::db_access::*;use super::errors::MyError;use super::state::AppState;use actix_web::{web, HttpResponse};pub async fn health_check_handler(app_state: web::Data) -> HttpResponse {    let health_check_response = &app_state.health_check_response;    let mut visit_count = app_state.visit_count.lock().unwrap();    let response = format!("{} {} times", health_check_response, visit_count);    *visit_count += 1;    HttpResponse::Ok().json(&response)}use super::models::Course;pub async fn new_course(    new_course: web::Json,    app_state: web::Data,) -> HttpResponse {    let course = post_new_course_db(&app_state.db, new_course.into()).await;    HttpResponse::Ok().json(course)}pub async fn get_courses_for_tescher(    app_state: web::Data,    params: web::Path,) -> Result {    let teacher_id = i32::try_from(params.into_inner()).unwrap();    get_courses_for_teacher_db(&app_state.db, teacher_id)        .await        .map(|courses| HttpResponse::Ok().json(courses))}pub async fn get_courses_detail(    app_state: web::Data,    params: web::Path,) -> HttpResponse {    let teacher_id = i32::try_from(params.0).unwrap();    let course_id = i32::try_from(params.1).unwrap();    let course = get_courses_detail_db(&app_state.db, teacher_id, course_id).await;    HttpResponse::Ok().json(course)}#[cfg(test)]mod tests {    use super::*;    use actix_web::http::StatusCode;    use dotenv::dotenv;    use sqlx::postgres::PgPoolOptions;    use std::env;    use std::sync::Mutex;    #[actix_rt::test] // 异步测试    async fn post_course_test() {        dotenv().ok();        let db_url = env::var("DATABASE_URL").expect("DATABASE_URL is not set");        let db_pool = PgPoolOptions::new().connect(&db_url).await.unwrap();        let app_state: web::Data = web::Data::new(AppState {            health_check_response: "".to_string(),            visit_count: Mutex::new(0),            db: db_pool,        });        let course = web::Json(Course {            teacher_id: 1,            name: "Test course".into(),            id: Some(3), // serial            time: None,        });        let resp = new_course(course, app_state).await;        assert_eq!(resp.status(), StatusCode::OK);    }    #[actix_rt::test]    async fn get_all_courses_success() {        dotenv().ok();        let db_url = env::var("DATABASE_URL").expect("DATABASE_URL is not set");        let db_pool = PgPoolOptions::new().connect(&db_url).await.unwrap();        let app_state: web::Data = web::Data::new(AppState {            health_check_response: "".to_string(),            visit_count: Mutex::new(0),            db: db_pool,        });        let teacher_id: web::Path = web::Path::from(1);        let resp = get_courses_for_tescher(app_state, teacher_id)            .await            .unwrap();        assert_eq!(resp.status(), StatusCode::OK);    }    #[actix_rt::test]    async fn get_one_course_success() {        dotenv().ok();        let db_url = env::var("DATABASE_URL").expect("DATABASE_URL is not set");        let db_pool = PgPoolOptions::new().connect(&db_url).await.unwrap();        let app_state: web::Data = web::Data::new(AppState {            health_check_response: "".to_string(),            visit_count: Mutex::new(0),            db: db_pool,        });        let params: web::Path = web::Path::from((1, 1));        let resp = get_courses_detail(app_state, params).await;        assert_eq!(resp.status(), StatusCode::OK);    }}

测试

ws on  main via ? 1.67.1 via ? base ➜ cargo test --bin teacher-service get_all_courses_success   Compiling webservice v0.1.0 (/Users/qiaopengjun/rust/ws/webservice)warning: unused variable: `msg`  --> webservice/src/bin/../errors.rs:39:30   |39 |             MyError::DBError(msg) | MyError::ActixError(msg) => StatusCode::INTERNAL_SERVER_ERROR,   |                              ^^^                        ^^^   |   = note: `#[warn(unused_variables)]` on by defaulthelp: if this is intentional, prefix it with an underscore   |39 |             MyError::DBError(_msg) | MyError::ActixError(_msg) => StatusCode::INTERNAL_SERVER_ERROR,   |                              ~~~~                        ~~~~warning: unused variable: `msg`  --> webservice/src/bin/../errors.rs:40:31   |40 |             MyError::NotFound(msg) => StatusCode::NOT_FOUND,   |                               ^^^ help: if this is intentional, prefix it with an underscore: `_msg`warning: `webservice` (bin "teacher-service" test) generated 2 warnings (run `cargo fix --bin "teacher-service" --tests` to apply 2 suggestions)    Finished test [unoptimized + debuginfo] target(s) in 1.55s     Running unittests src/bin/teacher-service.rs (target/debug/deps/teacher_service-32d6a48d6ee3c4b4)running 1 testtest handlers::tests::get_all_courses_success ... oktest result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 2 filtered out; finished in 0.01sws on  main [✘!?] via ? 1.67.1 via ? base took 2.1s ➜ 

webservice/src/db_access.rs

use super::errors::MyError;use super::models::*;use chrono::NaiveDateTime;use sqlx::postgres::PgPool;pub async fn get_courses_for_teacher_db(    pool: &PgPool,    teacher_id: i32,) -> Result<Vec, MyError> {    let rows = sqlx::query!(        r#"SELECT id, teacher_id, name, time FROM course WHERE teacher_id = $1"#,        teacher_id    )    .fetch_all(pool)    .await?;    let courses: Vec = rows        .iter()        .map(|row| Course {            id: Some(row.id),            teacher_id: row.teacher_id,            name: row.name.clone(),            time: Some(NaiveDateTime::from(row.time.unwrap())),        })        .collect();    match courses.len() {        0 => Err(MyError::NotFound("Courses not found teacher".into())),        _ => Ok(courses),    }}pub async fn get_courses_detail_db(    pool: &PgPool,    teacher_id: i32,    course_id: i32,) -> Result {    let row = sqlx::query!(        r#"SELECT id, teacher_id, name, time FROM course WHERE teacher_id = $1 and id = $2"#,        teacher_id,        course_id    )    .fetch_one(pool)    .await;    if let Ok(row) = row {        Ok(Course {            id: Some(row.id),            teacher_id: row.teacher_id,            name: row.name.clone(),            time: Some(NaiveDateTime::from(row.time.unwrap())),        })    } else {        Err(MyError::NotFound("Course Id not found".into()))    }}pub async fn post_new_course_db(pool: &PgPool, new_course: Course) -> Result {    let row = sqlx::query!(        r#"INSERT INTO course (id, teacher_id, name) VALUES ($1, $2, $3)        RETURNING id, teacher_id, name, time"#,        new_course.id,        new_course.teacher_id,        new_course.name    )    .fetch_one(pool)    .await?;    Ok(Course {        id: Some(row.id),        teacher_id: row.teacher_id,        name: row.name.clone(),        time: Some(NaiveDateTime::from(row.time.unwrap())),    })}

webservice/src/handlers.rs

use super::db_access::*;use super::errors::MyError;use super::state::AppState;use actix_web::{web, HttpResponse};pub async fn health_check_handler(app_state: web::Data) -> HttpResponse {    let health_check_response = &app_state.health_check_response;    let mut visit_count = app_state.visit_count.lock().unwrap();    let response = format!("{} {} times", health_check_response, visit_count);    *visit_count += 1;    HttpResponse::Ok().json(&response)}use super::models::Course;pub async fn new_course(    new_course: web::Json,    app_state: web::Data,) -> Result {    post_new_course_db(&app_state.db, new_course.into())        .await        .map(|course| HttpResponse::Ok().json(course))}pub async fn get_courses_for_tescher(    app_state: web::Data,    params: web::Path,) -> Result {    let teacher_id = i32::try_from(params.into_inner()).unwrap();    get_courses_for_teacher_db(&app_state.db, teacher_id)        .await        .map(|courses| HttpResponse::Ok().json(courses))}pub async fn get_courses_detail(    app_state: web::Data,    params: web::Path,) -> Result {    let teacher_id = i32::try_from(params.0).unwrap();    let course_id = i32::try_from(params.1).unwrap();    get_courses_detail_db(&app_state.db, teacher_id, course_id)        .await        .map(|course| HttpResponse::Ok().json(course))}#[cfg(test)]mod tests {    use super::*;    use actix_web::http::StatusCode;    use dotenv::dotenv;    use sqlx::postgres::PgPoolOptions;    use std::env;    use std::sync::Mutex;    #[ignore]    #[actix_rt::test] // 异步测试    async fn post_course_test() {        dotenv().ok();        let db_url = env::var("DATABASE_URL").expect("DATABASE_URL is not set");        let db_pool = PgPoolOptions::new().connect(&db_url).await.unwrap();        let app_state: web::Data = web::Data::new(AppState {            health_check_response: "".to_string(),            visit_count: Mutex::new(0),            db: db_pool,        });        let course = web::Json(Course {            teacher_id: 1,            name: "Test course".into(),            id: Some(5), // serial            time: None,        });        let resp = new_course(course, app_state).await.unwrap();        assert_eq!(resp.status(), StatusCode::OK);    }    #[actix_rt::test]    async fn get_all_courses_success() {        dotenv().ok();        let db_url = env::var("DATABASE_URL").expect("DATABASE_URL is not set");        let db_pool = PgPoolOptions::new().connect(&db_url).await.unwrap();        let app_state: web::Data = web::Data::new(AppState {            health_check_response: "".to_string(),            visit_count: Mutex::new(0),            db: db_pool,        });        let teacher_id: web::Path = web::Path::from(1);        let resp = get_courses_for_tescher(app_state, teacher_id)            .await            .unwrap();        assert_eq!(resp.status(), StatusCode::OK);    }    #[actix_rt::test]    async fn get_one_course_success() {        dotenv().ok();        let db_url = env::var("DATABASE_URL").expect("DATABASE_URL is not set");        let db_pool = PgPoolOptions::new().connect(&db_url).await.unwrap();        let app_state: web::Data = web::Data::new(AppState {            health_check_response: "".to_string(),            visit_count: Mutex::new(0),            db: db_pool,        });        let params: web::Path = web::Path::from((1, 1));        let resp = get_courses_detail(app_state, params).await.unwrap();        assert_eq!(resp.status(), StatusCode::OK);    }}

测试

ws on  main [✘!?] via ? 1.67.1 via ? base took 2.1s ➜ cargo test --bin teacher-service                              Compiling webservice v0.1.0 (/Users/qiaopengjun/rust/ws/webservice)warning: unused variable: `msg`  --> webservice/src/bin/../errors.rs:39:30   |39 |             MyError::DBError(msg) | MyError::ActixError(msg) => StatusCode::INTERNAL_SERVER_ERROR,   |                              ^^^                        ^^^   |   = note: `#[warn(unused_variables)]` on by defaulthelp: if this is intentional, prefix it with an underscore   |39 |             MyError::DBError(_msg) | MyError::ActixError(_msg) => StatusCode::INTERNAL_SERVER_ERROR,   |                              ~~~~                        ~~~~warning: unused variable: `msg`  --> webservice/src/bin/../errors.rs:40:31   |40 |             MyError::NotFound(msg) => StatusCode::NOT_FOUND,   |                               ^^^ help: if this is intentional, prefix it with an underscore: `_msg`warning: `webservice` (bin "teacher-service" test) generated 2 warnings (run `cargo fix --bin "teacher-service" --tests` to apply 2 suggestions)    Finished test [unoptimized + debuginfo] target(s) in 1.27s     Running unittests src/bin/teacher-service.rs (target/debug/deps/teacher_service-32d6a48d6ee3c4b4)running 3 teststest handlers::tests::get_one_course_success ... oktest handlers::tests::get_all_courses_success ... oktest handlers::tests::post_course_test ... oktest result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.02sws on  main [✘!?] via ? 1.67.1 via ? base ➜ ws on  main [✘!?] via ? 1.67.1 via ? base ➜ cargo test --bin teacher-service                           Compiling webservice v0.1.0 (/Users/qiaopengjun/rust/ws/webservice)warning: unused variable: `msg`  --> webservice/src/bin/../errors.rs:39:30   |39 |             MyError::DBError(msg) | MyError::ActixError(msg) => StatusCode::INTERNAL_SERVER_ERROR,   |                              ^^^                        ^^^   |   = note: `#[warn(unused_variables)]` on by defaulthelp: if this is intentional, prefix it with an underscore   |39 |             MyError::DBError(_msg) | MyError::ActixError(_msg) => StatusCode::INTERNAL_SERVER_ERROR,   |                              ~~~~                        ~~~~warning: unused variable: `msg`  --> webservice/src/bin/../errors.rs:40:31   |40 |             MyError::NotFound(msg) => StatusCode::NOT_FOUND,   |                               ^^^ help: if this is intentional, prefix it with an underscore: `_msg`warning: `webservice` (bin "teacher-service" test) generated 2 warnings (run `cargo fix --bin "teacher-service" --tests` to apply 2 suggestions)    Finished test [unoptimized + debuginfo] target(s) in 0.71s     Running unittests src/bin/teacher-service.rs (target/debug/deps/teacher_service-32d6a48d6ee3c4b4)running 3 teststest handlers::tests::post_course_test ... ignoredtest handlers::tests::get_one_course_success ... oktest handlers::tests::get_all_courses_success ... oktest result: ok. 2 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0.01sws on  main [✘!?] via ? 1.67.1 via ? base ➜ 

本文来自博客园，作者：QIAOPENGJUN，转载请注明原文链接：https://www.cnblogs.com/QiaoPengjun/p/17445127.html