node.js 使用Fetch API时如何设置请求头的内容类型
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How to set the content-type of request header when using Fetch APi
提问by user1526912
I am using npm 'isomorphic-fetch' to send requests. The problem I am experiencing is I am unable to set the content-type of the request header.
我正在使用 npm 'isomorphic-fetch' 发送请求。我遇到的问题是我无法设置请求标头的内容类型。
I set a content type of application/json , however the request header are being set to text/plain.
我将内容类型设置为 application/json ，但是请求标头被设置为 text/plain。
import 'isomorphic-fetch';
sendRequest(url, method, body) {
const options = {
method: method,
headers:{'content-type': 'application/json'},
mode: 'no-cors'
};
options.body = JSON.stringify(body);
return fetch(url, options);
}
When I examine the request in my browser the content type is o :
当我在浏览器中检查请求时，内容类型为 o ：
content-type:text/plain;charset=UTF-8
Can anyone explain why I am unable to set this property?
谁能解释为什么我无法设置此属性？
回答by RTS
You need to create a fetch headers object.
您需要创建一个 fetch headers 对象。
sendRequest(url, method, body) {
const options = {
method: method,
headers: new Headers({'content-type': 'application/json'}),
mode: 'no-cors'
};
options.body = JSON.stringify(body);
return fetch(url, options);
}
回答by user1526912
I found the answer after reading the following article:
我在阅读以下文章后找到了答案：
https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#Headers
https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#Headers
GuardSince headers can be sent in requests and received in responses, and have various limitations about what information can and should be mutable, headers objects have a guard property. This is not exposed to the Web, but it affects which mutation operations are allowed on the headers object.
Possible guard values are:
none: default.request: guard for a headers object obtained from a request (Request.headers).request-no-cors: guard for a headers object obtained from a request created withRequest.modeno-cors.response: guard for a Headers obtained from a response (Response.headers).immutable: Mostly used for ServiceWorkers; renders a headers object read-only.Note: You may not append or set a
requestguarded Headers'Content-Lengthheader. Similarly, insertingSet-Cookieinto a response header is not allowed: ServiceWorkers are not allowed to set cookies via synthesized responses.
警卫由于标头可以在请求中发送并在响应中接收，并且对于哪些信息可以和应该是可变的有各种限制，因此标头对象具有保护属性。这不会暴露给 Web，但它会影响 headers 对象上允许进行哪些更改操作。
可能的保护值是：
none： 默认。request: 保护从请求 (Request.headers) 中获得的标头对象。request-no-cors: 保护从使用创建的请求获得的标头对象Request.modeno-cors。response: 保护从响应 (Response.headers) 中获得的 Headers 。immutable: 主要用于 ServiceWorkers；将 headers 对象呈现为只读。注意：您不能附加或设置受
request保护的 HeadersContent-Length标头。同样，Set-Cookie不允许插入响应头：ServiceWorker 不允许通过合成响应设置 cookie。
When the options mode property is set to no-cors the request header values are immutable.
When the options mode property is set to no-cors the request header values are immutable.
Instead I set the mode property to cors.
相反，我将模式属性设置为 cors。
