我如何获取Profise对象中从Fetch Api返回的错误值? [英] How can i get errors value inside Promise object which return from Fetch Api?

问题描述

我有这样的提取请求.

fetch(deafaultUrl + '/v1/users/',
        {
            headers: {
                'Content-Type': 'application/json'
            },
            method: "POST",
            body: JSON.stringify(userInfoParams)
        })
        .then(function(response) {
            console.log(response);
            console.log(response.json());

            // not working never go into this function
            response.json().then(function(value) {
                console.log('access promise');
                console.log(value); // "Success"
            });

            if (response.status !== 200 && response.status !== 201) {
                throw new Error("Bad response from server");
            }
        })
        .then(function(json){

            console.log("succeed json re");
            console.log(json);
            dispatch(update_user(json));

        }) 

所以当我控制台这个console.log(response.json());

我明白了

但是Promise功能似乎无法锻炼.

But it seems like Promise function doesnot workout.

那么我该如何在[[PromiseValue]]内部获取错误对象?

So how can i get errors Object inside [[PromiseValue]]?

谢谢！

推荐答案

要从诺言中获取错误，您可以这样做:

To get the error from the promise, you can do it like this:

promise.then(function(data) {
  }, function(error) {...}

OR

要获得承诺错误，您还可以使用.catch()块

To got promise error you can also use .catch() block

 .then(){...}
 .catch(){..}

永远不要去这部分，因为服务器已经发送了响应

Never going to this part because server already sent the response

.then(function(response) {
            console.log(response);
            console.log(response.json());

            // not working never go into this function
            response.json().then(function(value) {
                console.log('access promise');
                console.log(value); // "Success"
            });

您可以通过以下方式编写代码:

You can write your code in this way:

fetch(deafaultUrl + '/v1/users/', {
        headers: {
            'Content-Type': 'application/json'
        },
        method: "POST",
        body: JSON.stringify(userInfoParams)
    })
    .then(function(response) {
        // if request is successful
    }
    .catch(err){
         // if got error
     }
    });

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