CORS 策略已阻止从 '' from origin '' 获取数据：请求的资源上不存在 'Access-Control-Allow-Origin' 标头

I have this api (method get) that is connected to a lambda function that does a simple select from a database, if i test the endpoint with postman with a null body it does work (if i understood, postman is not under the same CORS policy), as well as typing the endpoint on the browser.

但是当我尝试从简单的 js 中获取数据时，我收到错误： 从源“http://localhost”获取“...”的访问已被 CORS 策略阻止：请求的资源上不存在“Access-Control-Allow-Origin”标头。如果不透明响应满足您的需求，请将请求模式设置为“no-cors”以在禁用 CORS 的情况下获取资源。

I enabled CORS in API Gateway, both with the Enable CORS option and with the Enable API Gateway CORS when creating a new resource

If i test my endpoint with gateway, i also get that Allow-content-allow-origin : * is in my response header :

我应该怎么做才能解决这个问题？

这是 JS 获取：

    console.log("pre fetch");

Show();
console.log("post fetch");
function Show(){
fetch("...").then(onResponse);//.then(onJson);
}
function onResponse(response){
    console.log(response);
    return response.json();
}

我删除了 onJson 以避免混淆，但即使如此，它仍然存在同样的问题。

尝试将其也包含在您的函数中，就像这样， 我希望这会起作用：

const headers = {'Content-Type':'application/json',
                    'Access-Control-Allow-Origin':'*',
                    'Access-Control-Allow-Methods':'POST,PATCH,OPTIONS'}
const response = {
    statusCode: 200,
    headers:headers,
    body: JSON.stringify(X),
};
return response;

Here X是您想要返回的响应。