Can't return from a function - mysql

Question

So what i am trying to do is, create a function, use mysql(don't care how, but i found an npm for it so using that for now.) to get information from my database and then feed my json with it. It works fine as long as the console.log() is in the right spot, but i have to return it so i have to move it further down. But when i do that, it won't show in my other file, which i need it to be at.
I have 2 of the basically same script, one is just for another faction.
- So i will only show one, as if i find a solution for one of them, i have a solution for both.
get_ally_online_players: function (guild) {
con.query("SELECT * FROM user_dbs WHERE guild='"+ guild +"'", function (err, result, fields) {
var con2 = mysql.createConnection({
host: result[0].host,
user: result[0].username,
password: result[0].password,
database: result[0].database
})
con2.connect()
con2.query("SELECT * FROM characters WHERE online='1' AND race=1 OR race=3 OR race=4 OR race=7 OR race=11", function (err, result, fields) {
allycount = 0
console.dir(result)
result.forEach(function(result) {
allycount = allycount+1
})
return allycount
});
con2.end()
});
}
Here is where i try to have it:
if(recieved.content === "!status")
{
var horde_players
var ally_players
horde_players == guilddb.get_horde_online_players("585919060722712670")
ally_players == guilddb.get_ally_online_players("585919060722712670")
console.log(guilddb.test())
//console.log(ally_players)
recieved.channel.send(ally_players + " : " + horde_players)
}
I have tried so many things... I've also read that you have to use callbacks since it's apparently going too fast, like it can't query before...
I'd like to stay away from the callback though, since it seems like a hassle to have inside the script. But if it's absolutely necessary, so be it. It returns with "undefined" btw. I have also tried to use promises instead and put a setTimeout function etc.

Answer 1

First of all, sorry about my English.
Actually you are commiting some mistakes.
You where commiting a mistake asigning values to horde_players and ally_players values
if (recieved.content === "!status") {
var horde_players
var ally_players
horde_players = guilddb.get_horde_online_players("585919060722712670")
ally_players = guilddb.get_ally_online_players("585919060722712670")
console.log(guilddb.test())
//console.log(ally_players)
recieved.channel.send(ally_players + " : " + horde_players)
}
With (==) you are comparing values, not setting.
Now lets talk about async operations.
I prepared an example. This is like in your case, you are trying to run two async operations that may finish at different times, but you need both of them finished before running something else. Try to run it:
function async1(id, callback) {
setTimeout(function() {
callback('The user with ' + id + ' is called Sergio');
}, 6000);
}
function async2(id, callback) {
setTimeout(function() {
callback('The user with ' + id + ' is called Jack');
}, 2000);
}
var result1;
var result2;
async1(1, function(result) {
result1 = result;
});
async2(2, function(result) {
result2 = result;
});
console.log('Finished result: ' + result1 + result2); // Finished result: undefined undefined
The finished result was run before finishing both async operations. Bad...
With callbacks, we need to nest the functions (if you had to do more async operations, you could lead into Callback Hell)
function async1(id, callback) {
setTimeout(function() {
callback('The user with ' + id + ' is called Sergio');
}, 6000);
}
function async2(id, callback) {
setTimeout(function() {
callback('The user with ' + id + ' is called Jack');
}, 2000);
}
var result1;
var result2;
async1(1, function(result) {
result1 = result;
async2(2, function(result) {
result2 = result;
console.log('Finished result: ' + result1 + result2); // 'Finished result: The user with 1 is called SergioThe user with 2 is called Jack
});
});
For your case, this would be my solution. Maybe I would improve more things like using const-let and ES6 features (async-await, arrow functions...), passing db connectors trought params... but maybe it's easier to you to understand now
var guilddb = {
get_horde_online_players: function(guild, callback) {
callback('Implement me!');
},
get_ally_online_players: function(guild, callback) {
con.query("SELECT * FROM user_dbs WHERE guild='" + guild + "'", function (err, result, fields) {
var con2 = mysql.createConnection({
host: result[0].host,
user: result[0].username,
password: result[0].password,
database: result[0].database
});
con2.connect();
con2.query("SELECT * FROM characters WHERE online='1' AND race=1 OR race=3 OR race=4 OR race=7 OR race=11", function (err, result, fields) {
var allycount = 0;
console.dir(result);
result.forEach(function(result) {
allycount = allycount+1
});
con2.end();
callback(allycount);
});
});
}
}
if (recieved.content === "!status") {
guilddb.get_horde_online_players("585919060722712670", function(result) {
var horde_players = result;
guilddb.get_ally_online_players("585919060722712670", function(result) {
var ally_players = result;
console.log(guilddb.test());
console.log(ally_players);
recieved.channel.send(ally_players + " : " + horde_players);
});
});
}
Hope it helps.

Answer 2

Your query is asynchronous so the function will implicitly return undefined before the query finishes.
Therefore, you will need to use callbacks or promises.
You can use callbacks like this:
// Accept a callback function as an argument
get_ally_online_players: function (guild, callback) {
con.query("SELECT * FROM user_dbs WHERE guild='"+ guild +"'", function (err, result, fields) {
var con2 = mysql.createConnection({
host: result[0].host,
user: result[0].username,
password: result[0].password,
database: result[0].database
})
con2.connect()
con2.query("SELECT * FROM characters WHERE online='1' AND race=1 OR race=3 OR race=4 OR race=7 OR race=11", function (err, result, fields) {
allycount = 0
console.dir(result)
result.forEach(function(result) {
allycount = allycount+1
})
// Pass the result to the callback function
callback(allycount)
})
con2.end()
})
}
...and then pass a callback function to get_ally_online_players that will receive the data when ready:
if (recieved.content === "!status") {
var horde_players
var ally_players
horde_players = guilddb.get_horde_online_players("585919060722712670")
// Pass a callback function that will receive the data when ready
guilddb.get_ally_online_players("585919060722712670", function(ally_players) {
console.log(ally_players)
recieved.channel.send(ally_players + " : " + horde_players)
})
}
I hope this helps.