Javascript 在NodeJS中循环后获取新数组值时遇到问题
由于我是NodeJS新手,我尝试了几种方法,比如在函数上使用async/await,但是当我尝试打印数组retrievevalue时,它似乎总是空的 即使尝试等待也无济于事,如果我在它推入数组的点打印retrieveValues,它将在控制台中显示,但在之后执行时不会显示Javascript 在NodeJS中循环后获取新数组值时遇到问题,javascript,node.js,npm,Javascript,Node.js,Npm,由于我是NodeJS新手,我尝试了几种方法,比如在函数上使用async/await,但是当我尝试打印数组retrievevalue时,它似乎总是空的 即使尝试等待也无济于事,如果我在它推入数组的点打印retrieveValues,它将在控制台中显示,但在之后执行时不会显示 router.post('/api/retrievefornotifications', (request, response) => { var requestBody = request.body;
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();
})
最后一个
console.log
在按下之前运行。
您将函数作为回调传递,因此它将在操作结束后运行。
我稍微清理了一下您的代码并移动了控制台.log
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: []
};
con.query('SELECT COUNT(*) as count_value FROM school.schoolinformation WHERE email = ? AND user_status = ?', [dataElement, 1], function (err, result, fields) {
if (!err) {
var suspended = result[0].count_value;
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();
});
})最后一个
控制台.log
在按下之前运行。
您将函数作为回调传递,因此它将在操作结束后运行。
我稍微清理了一下您的代码并移动了控制台.log
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: []
};
con.query('SELECT COUNT(*) as count_value FROM school.schoolinformation WHERE email = ? AND user_status = ?', [dataElement, 1], function (err, result, fields) {
if (!err) {
var suspended = result[0].count_value;
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();
});
})也许您可以尝试以下代码:
router.post('/api/retrievefornotifications',(请求、响应)=>{
var requestBody=request.body;
var响应码;
var-teacher=requestBody.teacher;
var notification=requestBody.notification;
var emails=helper.findemailaddress(通知);
控制台日志(电子邮件);
var retrieveValues={
收件人:[]
};
const result=new Promise((解析,拒绝)=>{con.query('SELECT COUNT(*)作为school.schoolinformation中的COUNT_值,其中email=?和user_status=?',[dataElement,1],函数(err,result,fields){
//con.query('选择COUNT(*)作为school.school信息中的COUNT_值,其中email=?和user_status=?;选择COUNT(*)作为school.registration关系中的COUNT_值2,其中teacher_email=?和student_email=?,[dataElement,1,teacher,dataElement],函数(err,result,fields){
//日志(“数据元素%s”,数据元素);
如果(!err){
//console.log(“计数值1:%s”,结果[0][0]。计数值);
//console.log(“计数值2:%s”,结果[1][0]。计数值2);
//var suspended=结果[0][0]。计数值;
//var registerWithTeacher=结果[1][0]。计数值;
//控制台日志(结果);
var suspended=结果[0]。计数值;
//是否存在此类电子邮件?(0-未暂停,1-暂停)-暂停
//如果1表示它是一个已注册的对-registerWithTeacher
//已在通知中提及
//他在老师那儿登记了
如果(暂停==0){
console.log(“推送%s”,数据元素);
解析(数据元);
}
否则{
响应代码=500;
writeResponse(responseCode,response,0);
}
}
否则{
响应代码=204;
writeResponse(responseCode,response,0);
}
});
//在这里做些事情
控制台日志(等待结果);
retrieveValues.recipients.push(等待结果);
console.log(retrieveValues);
response.end();
});
});
我希望它能帮助您。也许您可以尝试以下代码:
router.post('/api/retrievefornotifications',(请求、响应)=>{
var requestBody=request.body;
var响应码;
var-teacher=requestBody.teacher;
var notification=requestBody.notification;
var emails=helper.findemailaddress(通知);
控制台日志(电子邮件);
var retrieveValues={
收件人:[]
};
const result=new Promise((解析,拒绝)=>{con.query('SELECT COUNT(*)作为school.schoolinformation中的COUNT_值,其中email=?和user_status=?',[dataElement,1],函数(err,result,fields){
//con.query('选择COUNT(*)作为school.school信息中的COUNT_值,其中email=?和user_status=?;选择COUNT(*)作为school.registration关系中的COUNT_值2,其中teacher_email=?和student_email=?,[dataElement,1,teacher,dataElement],函数(err,result,fields){
//日志(“数据元素%s”,数据元素);
如果(!err){
//console.log(“计数值1:%s”,结果[0][0]。计数值);
//console.log(“计数值2:%s”,结果[1][0]。计数值2);
//var suspended=结果[0][0]。计数值;
//var registerWithTeacher=结果[1][0]。计数值;
//控制台日志(结果);
var suspended=结果[0]。计数值;
//是否存在此类电子邮件?(0-未暂停,1-暂停)-暂停
//如果1表示它是一个已注册的对-registerWithTeacher
//已在通知中提及
//他在老师那儿登记了
如果(暂停==0){
console.log(“推送%s”,数据元素);
解析(数据元);
}
否则{
响应代码=500;
writeResponse(responseCode,response,0);
}
}
否则{
响应代码=204;
writeResponse(responseCode,response,0);
}
});
//在这里做些事情
控制台日志(等待结果);
retrieveValues.recipients.push(等待结果);
console.log(retrieveValues);
response.end();
});
});
我希望它能帮助你。这能回答你的问题吗?这能回答你的问题吗?我真正想做的是用挂起的函数多次查询,并将其添加到retrieveValues数组列表中。你使用什么库进行sql连接?你只能等待
Promise
s。我使用的是MySQL这个模块没有支持承诺。您可以使用其他支持它的,但我相信您可以在没有async/aw的情况下做您想做的事情