When a Javascript function returns true/false, it can sometimes result in undefined

Question

When a Javascript function returns true/false, it can sometimes result in undefined

Currently, I am facing an issue with my function. Utilizing a MongoDB Database to validate if something exists, the objective is to return false when a data value is true and false otherwise.

Up until this point, everything seems to be functioning correctly. However, the function only returns "undefined". Despite spending over an hour testing various solutions, none have proven successful.

I am hoping that someone could assist me in ensuring the function properly returns true or false.

Note: I even attempted an asynchronous approach without success.

function CheckActiveGamesPlayer1(memberid) {
            console.log("3")
            db.findOne({ GuildID: guild.id, Player1: memberid }, async(err, data) => {
                if (data.Ingame === true) {
                    console.log("4")
                    Embed.setDescription(`<@${memberid}> is in an active game. Can't start the game!`).setColor("RANDOM");
                    channel.send({ embeds: [Embed], ephemeral: true })
                    return false;
                } else {
                    console.log("5")
                    return true;
                }

            })

        }

javascript mongodb function

Answer 1

Answer №1

It seems like the issue lies in the fact that CheckActiveGamesPlayer1 function is not returning anything directly. However, there is a return value within the db.findOne callback.

If you're unsure how to call the CheckActiveGamesPlayer1 function, I recommend wrapping it in a Promise so that you can either use await or .then to handle the response you need.

function CheckActiveGamesPlayer1(memberid) {
  console.log('3');
  return new Promise( (resolve, reject) => {
    db.findOne({ GuildID: guild.id, Player1: memberid }, async (err, data) => {
      if (data.Ingame === true) {
        console.log('4');
        Embed.setDescription(`<@${memberid}> is in an active game. Can't start the game!`).setColor('RANDOM');
        channel.send({ embeds: [Embed], ephemeral: true });
        resolve(false);
      } else {
        console.log('5');
        resolve(true);
      }
    });
  });
}

To retrieve the response from your function, you can use .then.

Example:

CheckActiveGamesPlayers1(1).then( result => console.log(result) );

Alternatively, you can make your CheckActiveGamesPlayer1 function asynchronous and simply await its response.

Example:

async function CheckActiveGamesPlayer1(memberid) { ... }
const result = await CheckActiveGamesPlayers1(1);

If your version of mongo supports promises with db.findOne, you might be able to directly return it instead of using callbacks. Just ensure that db.findOne returns a promise for this to work smoothly.

https://www.mongodb.com/docs/drivers/node/current/usage-examples/findOne/

Answer 2

It seems like the issue lies in the fact that CheckActiveGamesPlayer1 function is not returning anything directly. However, there is a return value within the db.findOne callback.

If you're unsure how to call the CheckActiveGamesPlayer1 function, I recommend wrapping it in a Promise so that you can either use await or .then to handle the response you need.

function CheckActiveGamesPlayer1(memberid) {
  console.log('3');
  return new Promise( (resolve, reject) => {
    db.findOne({ GuildID: guild.id, Player1: memberid }, async (err, data) => {
      if (data.Ingame === true) {
        console.log('4');
        Embed.setDescription(`<@${memberid}> is in an active game. Can't start the game!`).setColor('RANDOM');
        channel.send({ embeds: [Embed], ephemeral: true });
        resolve(false);
      } else {
        console.log('5');
        resolve(true);
      }
    });
  });
}

To retrieve the response from your function, you can use .then.

Example:

CheckActiveGamesPlayers1(1).then( result => console.log(result) );

Alternatively, you can make your CheckActiveGamesPlayer1 function asynchronous and simply await its response.

Example:

async function CheckActiveGamesPlayer1(memberid) { ... }
const result = await CheckActiveGamesPlayers1(1);

If your version of mongo supports promises with db.findOne, you might be able to directly return it instead of using callbacks. Just ensure that db.findOne returns a promise for this to work smoothly.

https://www.mongodb.com/docs/drivers/node/current/usage-examples/findOne/

Answer 3

Answer №2

Consider implementing the following approach. It is likely that db.findOne returns a promise, allowing you to use await db.findOne without needing a callback function. You can then proceed with your code execution as usual after that.

async function VerifyActiveGamesPlayer(memberId) {
    console.log("Checking active games...");
    const gameData = await db.findOne({ UserID: memberId });
    if (gameData.isPlaying === true) {
        console.log("User is currently in an active game.");
        Embed.setDescription(`Player <@${memberId}> is already in a game. Unable to start another one.`).setColor("RED");
        channel.send({ embeds: [Embed], ephemeral: true })
        return false;
    } else {
        console.log("User is not in any active games.");
        return true;
    }
}

Answer 4

Consider implementing the following approach. It is likely that db.findOne returns a promise, allowing you to use await db.findOne without needing a callback function. You can then proceed with your code execution as usual after that.

async function VerifyActiveGamesPlayer(memberId) {
    console.log("Checking active games...");
    const gameData = await db.findOne({ UserID: memberId });
    if (gameData.isPlaying === true) {
        console.log("User is currently in an active game.");
        Embed.setDescription(`Player <@${memberId}> is already in a game. Unable to start another one.`).setColor("RED");
        channel.send({ embeds: [Embed], ephemeral: true })
        return false;
    } else {
        console.log("User is not in any active games.");
        return true;
    }
}

Answer 5

Answer №3

This function is synchronous, meaning it runs before the async callback function is called.

To resolve this issue, consider converting the function to an async function and using the "await" keyword.

Answer 6

This function is synchronous, meaning it runs before the async callback function is called.

To resolve this issue, consider converting the function to an async function and using the "await" keyword.

When a Javascript function returns true/false, it can sometimes result in undefined

Answer №1

Answer №2

Answer №3

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