当我尝试插入数据库时​​。我未定义＆＃39;所有行的值

Question

我想保存我的输出返回数据库的这个json数组。但是，我真的不知道如何使用nodejs将其转换为字符串。当我尝试插入数据库时​​。我未定义＆＃39;所有行的值。 有什么选择？我想要一个json文件文件作为输出，以及想要在mysql db中插入值。请帮忙。感谢

var express = require('express');
var fs = require('fs');
var mysql = require('mysql');
var request = require('request');
var cheerio = require('cheerio');
var bodyParser = require('body-parser');
var app     = express();

var output;
app.use(bodyParser.json())

app.get('/scrape', function(req, res){
    url = 'https://raitalumni.dypatil.edu/events/?tag=live';

    request(url, function(error, response, html){
        if(!error){
            var $ = cheerio.load(html);
            var json = {
                            title : [],
                            date  : [],
                            month : [],
                            venue : [],
                            link : []
                       };
             output = {
                            events : []
                         };

            $('p.event_name').each(function(){
                json.title.push($(this).text());
            });




            $('p.calendar_date').each(function(){
                json.date.push($(this).text());
            });

            $('span.calendar_month').each(function(){
                json.month.push($(this).text());
            });


            //var fulldate = $('p.calendar_date').concat($('p.calendar_day')).text();
            //console.log('all records: ' + fulldate);

            $('p.event_venue').each(function(){
                json.venue.push($(this).text());
            });

        // var title = $('p.event_name').each(function(){$(this).text()});



            for(var i=0; i<json.title.length; i++){
                output.events[i] = {
                    title : json.title[i],
                    date : json.date[i],
                    month : json.month[i],
                    venue : json.venue[i],
                    link : url
                }
            }

         var connection = mysql.createConnection({
        host: '127.0.0.1',
        port: 3306,
        user: 'root',
        password: '',
        database: 'raithub'
    });


connection.connect(function(error){
   if(!!error){
      console.log('Error');
   }else{
      console.log('Connected to the database!');
   }
});



       var scrape = JSON.stringify(output, null, 4);
       //var obj = JSON.parse(output);
       //console.log(obj);

           var query = connection.query("INSERT INTO scrapped_data (title,date,month,venue,link) VALUES ('" + output.title + "', '" + output.date + "', '" + output.month + "', '" + output.venue + "', '" + output.link + "');", scrape, function(err, result) {
     if(err) throw err;
     console.log('data inserted');
});


            fs.writeFile('output4.json', JSON.stringify(output, null, 4), function(err){
                console.log('File successfully written! - Check your project directory for the output.json file');
            })

            res.send('Check your console!')         
        }
        else {
            console.log("Network Error, please try again later")
        }
    })
})
app.listen('8000')
console.log('Server running on port 8081');
exports = module.exports = app;     

output.json：

{
    "events": [
        {
            "title": "Convocation 2017",
            "date": "25",
            "month": "Feb",
            "venue": "Venue: Ramrao Adik Institute of Technology, Nerul",
            "link": "https://raitalumni.dypatil.edu/events/?tag=live"
        },
        {
            "title": "RAIT Alumni Meet 2017",
            "date": "18",
            "month": "Feb",
            "venue": "Venue: Ramrao Adik Institute of Technology, Nerul",
            "link": "https://raitalumni.dypatil.edu/events/?tag=live"
        }
    ]
}

Answer 1

我认为我发现了你的问题。 在这些行中，您将创建一个事件数组，这些事件是输出对象的一部分。

for (var i = 0; i < json.title.length; i++) {
                output.events[i] = {
                    title: json.title[i],
                    date: json.date[i],
                    month: json.month[i],
                    venue: json.venue[i],
                    link: url
                }
            }

因此，在您的数据库插入中，您应该将output.title更改为output.events[i].title，依此类推：

for (let i = 0; i < json.title.length; ++i)
var query = connection.query("INSERT INTO scrapped_data (title,date,month,venue,link) VALUES ('" + output.events[i].title + "', '" + output.events[i].date + "', '" + output.events[i].month + "', '" + output.events[i].venue + "', '" + output.events[i].link + "');", scrape, function(err, result) {
    if (err) throw err;
    console.log('data inserted');
});

我还会将第二个json.title.length中的for更改为output.events.length。 您必须逐行插入这些事件。这就是你未定义的原因，因为output没有title属性。