Writing data from txt file to database in node js - sql

Question

I read data from a text file:
const byline = require('byline');
const fs = require('fs');
var stream = byline(fs.createReadStream('C:/Users/../test.txt'));
var index = 0;
var headers;
var data = [];
stream.on('data', function(line) {
var currentData;
var entry;
var i;
line = line.toString(); // Convert the buffer stream to a string line
//line = Buffer.from(line, 'latin1').toString();
if (index === 0) {
headers = line.split(/[ ]+/);
} else {
currentData = line.split(/[ ]+/);
entry = {};
for (i = 0; i < headers.length; i++) {
entry[headers[i]] = currentData[i];
}
data.push(entry);
}
index++;
});
stream.on("error", function(err) {
console.log(err);
});
stream.on("end", function() {
console.log(data);
console.log("Done");
});
That works just fine. So now i am trying to write this into a my database. Therefore i implemented this part at the end of the stream, when all of the data has been read.
stream.on("end", function() {
console.log(data);
console.log("Done");
for(h = 0; h < data.length; h++){
let name = data[h].Name;
let id = data[h].ID;
let text = data[h].Text;
let text1 = data[h].Text1;
let text2 = data[h].Text2;
let text3 = data[h].Text3;
Conn.query('INSERT INTO Config SET ? ', { Name: name, ID: id, Text: text, Text1: text1, Text2: text2, Text3: text3}, function (error, result, fields) {
if (error) throw error;
});
}
return res.send({ error: false, data: result, message: 'New configuration has been created.' });
});
But it seems like this does not work. What am i missing?

Answer 1

You can try the following
stream.on("end", function() {
console.log(data);
console.log("Done");
var promises = [];
for (h = 0; h < data.length; h++) {
let name = data[h].Name;
let id = data[h].ID;
let text = data[h].Text;
let text1 = data[h].Text1;
let text2 = data[h].Text2;
let text3 = data[h].Text3;
promises.push(new Promise(function insertIntoDatabase(resolve, reject) {
Conn.query('INSERT INTO Config SET ? ', {
Name: name,
ID: id,
Text: text,
Text1: text1,
Text2: text2,
Text3: text3
}, function(error, result, fields) {
if (error) reject(error);
else resolve();
})
}));
}
Promise.all(promises)
.then(function(data) {
res.send({
error: false,
data: result,
message: 'New configuration has been created.'
});
})
.catch(function(err) {
console.log("Error occured due to : ", err);
res.send({
error: true,
data: null,
message: 'Error during config'
});
});
//It is a bad practise to have a async operation that can throw error inside a synchronous loop
/*
for(h = 0; h < data.length; h++){
let name = data[h].Name;
let id = data[h].ID;
let text = data[h].Text;
let text1 = data[h].Text1;
let text2 = data[h].Text2;
let text3 = data[h].Text3;
Conn.query('INSERT INTO Config SET ? ', { Name: name, ID: id, Text: text, Text1: text1, Text2: text2, Text3: text3}, function (error, result, fields) {
if (error) throw error;
});
}
*/
});