database row counting with foreach though tables does not add value to variable

Question

this question is sort of an continue from Fetch variable from function into other function (under same function).

Since I created this function, the amount of tables to count is increasing. So I am trying to shorten the code by doing a foreach loop thru an array of table names and then add that count into variable. However the variable that should hold the count stays at 0. When I do a console.log on the returned data from database, then I see the correct database count.

RowDataPacket { c: 8695 } // From database
RowDataPacket { c: 12403 } // From database
0 // Variable that should hold the total count

This is my code so far

socket.on("test", function() {
    setInterval(async function() {
        dbCon.getConnection(function(err, connection) {
            if (err) {
                console.log(err);
                callback(true);
                return;
            }

            var rows = 0;
            var tables = ['logs', 'external_temp'];

            tables.forEach(async element => {
                await new Promise((resolve, reject) => {
                    connection.query("SELECT COUNT(id) AS c FROM `" + element + "`", function(error, result) {
                        if (error) {
                            reject(error);
                        }
                        console.log(result[0]);
                        rows += result[0].c;
                        resolve();
                    });
                })
            });

            var value = (rows).toLocaleString(
                undefined, {
                    minimumFractionDigits: 0
                }
            );

            console.log(value);
            connection.release();
        });
    }, 1000)
});

I am still very much a newbie to javascript and nodejs, so I hope someone can point me into the right direction.

score 0 · Accepted Answer · answered Aug 23 '22 at 10:58

I got it working, by using a let global variable, so now it count into the variable, this is my final code.

    socket.on("db_rows", function() {
        setInterval(async function() {
            dbCon.getConnection(function(err, connection) {
                if (err) {
                    console.log(err);
                    callback(true);
                    return;
                }
                
                const tables = ['logs', 'external_temp'];
                
                tables.forEach(async element => {
                    await new Promise((resolve, reject) => {
                    connection.query("SELECT COUNT(id) AS c FROM `" + element + "`", function(error, result) {
                        if (error) {
                            reject(error);
                        }
                        dbRows += result[0].c;
                        resolve();
                        
                    });
                })
                });
                
                connection.release();
                
                var value = (dbRows).toLocaleString(
                    undefined, {
                        minimumFractionDigits: 0
                    }
                );
                
                dbRows = 0;
    
                io.emit("db_rows", value);
            });
        }, timer_rows)
    });

database row counting with foreach though tables does not add value to variable

1 Answers1