反应本机提取不调用然后捕获 [英] react native fetch not calling then or catch
问题描述
我正在使用fetch在react-native中进行一些API调用,有时随机地fetch不会触发对服务器的请求,并且不会调用我的then或except块.这是随机发生的,我认为可能是比赛条件或类似情况.在一次这样的请求失败之后,对同一个API的请求永远不会被触发,直到我重新加载该应用程序为止.任何想法如何追究其背后的原因.我使用的代码如下.
I am using fetch to make some API calls in react-native, sometimes randomly the fetch does not fire requests to server and my then or except blocks are not called. This happens randomly, I think there might be a race condition or something similar. After failing requests once like this, the requests to same API never get fired till I reload the app. Any ideas how to trace reason behind this. The code I used is below.
const host = liveBaseHost;
const url = `${host}${route}?observer_id=${user._id}`;
let options = Object.assign({
method: verb
}, params
? {
body: JSON.stringify(params)
}
: null);
options.headers = NimbusApi.headers(user)
return fetch(url, options).then(resp => {
let json = resp.json();
if (resp.ok) {
return json
}
return json.then(err => {
throw err
});
}).then(json => json);
推荐答案
抓取可能会引发错误,并且您尚未添加catch块.试试这个:
Fetch might be throwing an error and you have not added the catch block. Try this:
return fetch(url, options)
.then((resp) => {
if (resp.ok) {
return resp.json()
.then((responseData) => {
return responseData;
});
}
return resp.json()
.then((error) => {
return Promise.reject(error);
});
})
.catch(err => {/* catch the error here */});
请记住,Promise通常具有以下格式:
Remember that Promises usually have this format:
promise(params)
.then(resp => { /* This callback is called is promise is resolved */ },
cause => {/* This callback is called if primise is rejected */})
.catch(error => { /* This callback is called if an unmanaged error is thrown */ });
我以这种方式使用它,因为我之前也遇到过同样的问题.
I'm using it in this way because I faced the same problem before.
让我知道它是否对您有帮助.
Let me know if it helps to you.
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