React Native Fetch:第二个承诺挂起 [英] React Native Fetch: second promise hanging

问题描述

React Native的获取存在奇怪的问题. 以前它可以正常工作，不确定我所做的更改，但已停止工作.

Strange problem with React Native's fetch. It was working previously, not sure what I've changed but it's stopped working.

login(data,success,fail){
    console.log('doing fb login');
    fetch(host+'/api/login?credentials='+data.credentials)
        .then( (response) => {
            console.log('got login response');
            return response.json();
        } )
        .then( json => {
            console.log('got login json');
            if(json.result!='fail'){
                success(json);
            } else {
                fail(json);
            }
            return json;
        })
        .catch((error) => {
          console.warn(error);
        });
}

问题是我看到第一条获取登录响应"消息，但随后挂起，直到我按下它触发获取登录json"并按预期继续的屏幕，什么都没有发生.

The issue is I see the first 'got login response' message, but then it just hangs, and nothing happens until I press the screen upon which it fires the 'got login json' and continues as expected.

令人沮丧的是，这种情况一直持续发生，我不明白为什么第二个.then()不能自动触发.

It's frustrating because this is happening consistently and I can't see why the second .then() isn't firing automatically.

非常感谢您的帮助.

发现了类似的问题:可以做什么?会导致本机反应缓慢获取?

似乎已经在查看它: https://github.com/facebook /react-native/issues/6679

此外，只有在启用Chrome调试工具后才能看到该行为...有趣

Also the behaviour is only seen whne the Chrome debug tools are enabled... interesting

推荐答案

response.json() is a promise, not a value. So it won't resolve for you. I would also check result based on response.status instead of json.result because for some case server's response won't convertible to json (401 for example).

.then( (response) => {
   if (response.status >= 200 && response.status < 300) {
      response.json().then((data) => success(data));
   } else {
      fail(response);
   }
})

这篇关于React Native Fetch:第二个承诺挂起的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！