sveltekit 类型错误：不可变

Question

我正在使用 sveltekit 1.0.0-next.483 运行 npm run dev -- --host 使用移动设备连接到端点时出现此错误：

typeError: immutable
    at Headers.append ([..]node_modules/undici/lib/fetch/headers.js:227:13)

此错误仅发生在连接到本地网络 IP 地址的移动设备上。

我的端点：src/routes/gqlendpoint/+server.ts

const base = 'http://localhost:4000/graphql';

export async function POST( opts: { request: Request} ): Promise<Response> {
    
    const { request } = opts;

    const body =  await request.json(); 

    const response = await fetch(base, {
        
        //credentials:"include",

        method: 'POST',
        
        headers: { 'Content-Type': 'application/json' },
        
        body: JSON.stringify(body)
    
    });

    return response;
}

我发现解决这种情况的唯一方法是在里面注释一行代码

node_modules/undici/lib/fetch/headers.js

// 3. If headers’s guard is "immutable", then throw a TypeError.
// 4. Otherwise, if headers’s guard is "request" and name is a
//    forbidden header name, return.
// Note: undici does not implement forbidden header names
if (this[kGuard] === 'immutable') {
  **//throw new TypeError('immutable')**
} else if (this[kGuard] === 'request-no-cors') {
  // 5. Otherwise, if headers’s guard is "request-no-cors":
  // TODO
}

这当然不是一个好的解决方案。

Answer 1

您必须返回新的响应正文以避免此问题，请参阅下面的示例代码。

  return new Response('test example')

代替返回响应；

Answer 2

把这个留给未来的我（和其他人）：

// return res // errors
return new Response(res.body, res) // works

在尝试制作迷你代理时遇到了这个：

const makeProxy: (proxyURL: string) => RequestHandler = proxyURL => async ({params, request}) => {
    let proxyNormalized = (new URL(proxyURL)).toString()
    let pathPos = request.url.indexOf(params.path)
    let requestedPath = request.url.substring(pathPos)
    let url = proxyNormalized + requestedPath

    let headers = Array.from(request.headers.entries()).filter(e => !e[0].startsWith(":"))
    console.log(headers)

    let res = await fetch(url, {
        body: request.body,
        cache: request.cache,
        credentials: request.credentials,
        headers,
        integrity: request.integrity,
        keepalive: request.keepalive,
        method: request.method,
        mode: request.mode,
        redirect: request.redirect,
        referrer: request.referrer,
        referrerPolicy: request.referrerPolicy,
        signal: request.signal,
    })

    // this looks stupid but it doesnt work otherwise
    return new Response(res.body, res)
}