在 NodeJS 中循环后获取新数组值时遇到问题 [英] Having problems getting new Array Value after looping in NodeJS

问题描述

由于我是 NodeJS 的新手，我尝试了几种方法，例如在我的函数上使用 async/await，但是当我尝试打印出数组retrieveValues 时，它似乎总是为空.

As i am new to NodeJS, I have tried several methods such as using async/await on my functions but when i try to print out the array retrieveValues it always seems to be empty.

即使尝试 await 也无济于事，如果我在它推入数组时打印出retrieveValues，它将显示在控制台中，但在我之后执行时不会显示.

Even trying await doesn't help it, if i print out the retrieveValues at the point that it pushes into the array, it will show in the console but not when i do it after.

router.post('/api/retrievefornotifications', (request, response) => {
    var requestBody = request.body;
    var responseCode;
    var teacher = requestBody.teacher;
    var notification = requestBody.notification;

    var emails = helper.findEmailAddresses(notification);

    console.log(emails);

    var retrieveValues = {
        recipients: []
    };

    async function suspended(dataElement) {
        con.query('SELECT COUNT(*) as count_value FROM school.schoolinformation WHERE email = ? AND user_status = ?', [dataElement, 1], function (err, result, fields) {
        // con.query('SELECT COUNT(*) as count_value FROM school.schoolinformation WHERE email = ? AND user_status = ?; SELECT COUNT(*) as count_value2 FROM school.registration_relationship WHERE teacher_email = ? AND student_email = ?', [dataElement, 1, teacher, dataElement], function (err, result, fields) {
            // console.log("dataElements %s", dataElement);
            if (!err) {
                // console.log("Count value 1: %s",result[0][0].count_value);
                // console.log("Count value 2: %s",result[1][0].count_value2);
                // var suspended = result[0][0].count_value;
                // var registerWithTeacher = result[1][0].count_value;

                // console.log(result);
                var suspended = result[0].count_value;
                // Does such an email exist? (0 - NOT SUSPENDED, 1 - SUSPENDED) - suspended
                // If 1 means it is a registered pair - registerWithTeacher
                // has been mentioned in notification
                // Is registered with the teacher
                if (suspended == 0) {
                    console.log("pushing %s", dataElement);
                    retrieveValues.recipients.push(dataElement);
                }
                else {
                    responseCode = 500;
                    helper.writeResponse(responseCode, response, 0);
                }
            }
            else {
                responseCode = 204;
                helper.writeResponse(responseCode, response, 0);
            }
        });
    }

    console.log(retrieveValues);
    response.end();

})

推荐答案

也许你可以试试下面的代码:

Maybe you can try this code below:

router.post('/api/retrievefornotifications', (request, response) => {
    var requestBody = request.body;
    var responseCode;
    var teacher = requestBody.teacher;
    var notification = requestBody.notification;

    var emails = helper.findEmailAddresses(notification);

    console.log(emails);

    var retrieveValues = {
        recipients: []
    };

      const result = new Promise((resolve, reject) => {  con.query('SELECT COUNT(*) as count_value FROM school.schoolinformation WHERE email = ? AND user_status = ?', [dataElement, 1], function (err, result, fields) {
        // con.query('SELECT COUNT(*) as count_value FROM school.schoolinformation WHERE email = ? AND user_status = ?; SELECT COUNT(*) as count_value2 FROM school.registration_relationship WHERE teacher_email = ? AND student_email = ?', [dataElement, 1, teacher, dataElement], function (err, result, fields) {
            // console.log("dataElements %s", dataElement);
            if (!err) {
                // console.log("Count value 1: %s",result[0][0].count_value);
                // console.log("Count value 2: %s",result[1][0].count_value2);
                // var suspended = result[0][0].count_value;
                // var registerWithTeacher = result[1][0].count_value;

                // console.log(result);
                var suspended = result[0].count_value;
                // Does such an email exist? (0 - NOT SUSPENDED, 1 - SUSPENDED) - suspended
                // If 1 means it is a registered pair - registerWithTeacher
                // has been mentioned in notification
                // Is registered with the teacher
                if (suspended == 0) {
                    console.log("pushing %s", dataElement);
                    resolve(dataElement);
                }
                else {
                    responseCode = 500;
                    helper.writeResponse(responseCode, response, 0);
                }
            }
            else {
                responseCode = 204;
                helper.writeResponse(responseCode, response, 0);
            }
        });

    // do some stuff here
    console.log(await result);

    retrieveValues.recipients.push(await result);
    console.log(retrieveValues);
    response.end();

});

});

希望能帮到你.

这篇关于在 NodeJS 中循环后获取新数组值时遇到问题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！