Question

我现在正在使用request节点包连接到API，制作一个节点应用程序。但是，当我发出API请求时，确定username和password的有效性的函数未按预期返回true。

到目前为止，这是我的代码：

const request = require("request")
const API_URL = <the_api_url>

const isValidLogin = (username, password) => {
    let success = false;
    let options = {
        url: API_URL,
        method: 'GET',
        auth: {
            user: username,
            pass: password
        }
    }
    request(options, (error, response, body) => {
        console.log(response.statusCode);
        if (error) {
            console.log(error)
        }
        if (response.statusCode == 200) {
            success = true;
        }
        else {
            success = false
        }
    })
    console.log(success)
    return success;
}

当我将无效的username和password传递到isValidLogin()时，它正确地返回false。我确实注意到response.statusCode是200，这意味着success是true，但是它没有按预期工作。

Answer 1

request()函数是异步的，这基本上意味着request()函数调用的结果将在将来返回。对于这种request()方法，将来会通过回调（即您正在测试statusCode的地方）返回结果。

要基于对success的调用正确返回request()结果，您需要执行以下两项操作之一：

将isValidLogin()定义为异步函数/返回将来会解决的承诺：

    /* Add asnyc means this function is now asynchronous */
    const isValidLogin = async (username, password) => {
        let success = false;
        let options = {
            url: API_URL,
            method: 'GET',
            auth: {
                user: username,
                pass: password
            }
        }

        /* return the result of the request when the request
        has completed */
        return await (new Promise(resolve, reject) => {
            request(options, (error, response, body) => {

                if (response.statusCode == 200) {
                    resolve(true);
                }
                else {
                    resolve(false);
                }
            });
        });
    }

    /* Requires the surrounding function to be async */
    const success = await isValidLogin('john', 'password');

或在isValidLogin完成后将回调传递给success，并以request()结果进行调用：


    /* onComplete is the added callback that is fired when request() completes */
    const isValidLogin = (username, password, onComplete) => {
        let success = false;
        let options = {
            url: API_URL,
            method: 'GET',
            auth: {
                user: username,
                pass: password
            }
        }
        request(options, (error, response, body) => {
            console.log(response.statusCode);
            if (error) {
                console.log(error)
            }
            if (response.statusCode == 200) {
                onComplete(true);
            }
            else {
                onComplete(false)
            }
        });
    }

    /* Usage example */
    isValidLogin('john', 'password', (success) => {
        console.log(`the request completed in the future 
                     and the result was ${success}`)
    })

请求的Javascript函数未返回正确值

1 个答案: