如何从 fetch API 返回 json 响应
我有这样的功能:
check_auth(){
fetch(Urls.check_auth(), {
credentials: 'include',
method: 'GET'
}).then(response => {
if(response.ok) return response.json();
}).then(json => {
return json.user_logged_in;
});
}
然后我尝试这样做:
if(this.check_auth()){
// do stuff
} else {
// do other stuff
}
但是，this.check_auth() 总是 undefined.
我在这里缺少什么?我认为在 fetch 的 then() 中是 resolved Promise 对象的位置，因此我认为当用户登录时我会得到 true在.但事实并非如此.
What am I missing here? I thought that within fetch's then() was where the resolved Promise object was therefore I thought that I'd get true when the user was logged in. But this is not the case.
任何帮助将不胜感激.
推荐答案
使用回调
check_auth(callback){
fetch(Urls.check_auth(), {
credentials: 'include',
method: 'GET'
}).then(response => {
if(response.ok) return response.json();
}).then(json => {
callback(json.user_logged_in);
});
}
check_auth(function(data) {
//processing the data
console.log(d);
});
在 React 中它应该更容易处理，您可以调用 fetch 并更新状态，因为每次使用 setState 更新状态时都会调用渲染方法，您可以使用状态进行渲染
In React it should be easier to handle, You can call a fetch and update the state, since on every update of state using setState the render method is called you can use the state to render
check_auth = () =>{
fetch(Urls.check_auth(), {
credentials: 'include',
method: 'GET'
}).then(response => {
if(response.ok) return response.json();
}).then(json => {
this.setState({Result: json.user_logged_in});
});
}
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