在 Rocket 中返回 HTTP 状态不是 200 的 JSON [英] Return JSON with an HTTP status other than 200 in Rocket

问题描述

我希望我的 Rocket API 有这样的路由:

I want my Rocket API to have a route like this:

#[post("create/thing", format = "application/json", data="<thing>")]

当客户端发送 { "name": "mything";}，一切都应该没问题，我知道该怎么做，但是当它发送 { "name": "foo";} 它应该响应如下:

When the client sends { "name": "mything" }, everything should be alright and I know how to do that, but when it sends { "name": "foo" } it should respond with something like this:

HTTP/1.1 422 Unprocessable Entity
Content-Type: application/json

{
  "errors": [
    {
      "status": "422",
      "title":  "Invalid thing name",
      "detail": "The name for a thing must be at least 4 characters long."
    }
  ]
}

如何在 Rocket 中使用 JSON 对象和不同于 200 的 HTTP 状态代码之类的结果进行响应?

How do I respond with a result like a JSON object and a HTTP status code different than 200 in Rocket?

这是我目前尝试过的:

• impl FromRequest 用于我的 Thing 类型.这让我可以选择一个状态代码，因为我可以编写自己的 from_request 函数，但我不能返回任何其他内容.
• 注册一个错误捕捉器，如this example，但这样我只能对一个没有上下文的 HTTP 状态代码做出反应.我有太多的失败模式，无法为每个模式保留一个 HTTP 状态代码.

• impl FromRequest for my Thing type. This lets me choose a status code as I can write my own from_request function, but I can't return anything else.
• Registering an error catcher like in this example, but this way I only can react to one HTTP status code without context. I have too many failure modes to reserve one HTTP status code for each.

推荐答案

在@hellow 的帮助下，我想通了.解决方案是为新结构 ApiResponse 实现 Responder 特征，该结构包含状态代码以及 Json.这样我就可以做我想做的事:

With @hellow's help, I figured it out. The solution is to implement the Responder trait for a new struct ApiResponse, which contains a status code as well the Json. This way I can do exactly what I wanted:

#[post("/create/thing", format = "application/json", data = "<thing>")]
fn put(thing: Json<Thing>) -> ApiResponse {
    let thing: Thing = thing.into_inner();
    match thing.name.len() {
        0...3 => ApiResponse {
            json: json!({"error": {"short": "Invalid Name", "long": "A thing must have a name that is at least 3 characters long"}}),
            status: Status::UnprocessableEntity,
        },
        _ => ApiResponse {
            json: json!({"status": "success"}),
            status: Status::Ok,
        },
    }
}

完整代码如下:

#![feature(proc_macro_hygiene)]
#![feature(decl_macro)]

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

use rocket::http::{ContentType, Status};
use rocket::request::Request;
use rocket::response;
use rocket::response::{Responder, Response};
use rocket_contrib::json::{Json, JsonValue};

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

#[derive(Debug)]
struct ApiResponse {
    json: JsonValue,
    status: Status,
}

impl<'r> Responder<'r> for ApiResponse {
    fn respond_to(self, req: &Request) -> response::Result<'r> {
        Response::build_from(self.json.respond_to(&req).unwrap())
            .status(self.status)
            .header(ContentType::JSON)
            .ok()
    }
}

#[post("/create/thing", format = "application/json", data = "<thing>")]
fn put(thing: Json<Thing>) -> ApiResponse {
    let thing: Thing = thing.into_inner();
    match thing.name.len() {
        0...3 => ApiResponse {
            json: json!({"error": {"short": "Invalid Name", "long": "A thing must have a name that is at least 3 characters long"}}),
            status: Status::UnprocessableEntity,
        },
        _ => ApiResponse {
            json: json!({"status": "success"}),
            status: Status::Ok,
        },
    }
}

fn main() {
    rocket::ignite().mount("/", routes![put]).launch();
}

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