If/Else block not working in Javascript

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I’m starting in Javascript and I’m creating a Whatsapp bot on Node.js and any block if that I put does not work and always goes to else.

It works that way:

  • Get the message;
  • Query the Sqlite database and check whether the number of the sender of the message is in the database and increases a variable (cnt);
  • A block if checks whether the variable cnt is greater than 0, if no, it means that the number is not in the bank and adds it.

The problem is that the block if doesn’t work, always returning else.

I’ve tried to use if (+cnt > +0), I tried using an array, putting all the numbers on it and using a arr.includes(message.author), but I get the same mistake, nothing I put in if works.

Am I forgetting something? It has to do with the database?

function start(client) {
  client.onMessage(async message => {
    db.serialize(function() {
      var cnt = 0
      db.each(`SELECT phone as phone, xp as xp, admin as admin, lastmsg as lastmsg, msgcount as msgcount FROM users`, (err, row) => {
        if (err) {
          console.error(err.message); 
        }
        if (Object.is(row.phone, message.author)) {
          cnt++;
        }
        console.log(message.author + " - " + row.phone + " - " + cnt)
      })
      if (+cnt > +0) {
        console.log(`Usuario ${message.author} já existe na database.`);
      }
      else 
      {
        db.serialize(function() {
          db.run(`INSERT INTO users (phone,xp,admin,lastmsg,msgcount) VALUES ("${message.author}",0,0,0,0)`);
          console.log(`Usuário ${message.author} adicionado a database.`);
        })
      }
    });
  });
}
javascript node.js sqlite if

  • I believe that db.each is an asynchronous function, so this if/else below should be within the function of callback.

  • if (+cnt > +0) - you don’t need those + (this is a way to convert strings to numbers, but both cnt how much 0 are already numbers, so this + is really unnecessary there)

1 answer

1


Surely the db.each(...) method is an asynchronous function, since it queries the database and needs it to respond, if/Else would have to be within this callback function or you can use the async/await Javascript, very common in Nodejs.

Example with if/Else inside callback function:

function start(client) {
  client.onMessage(async message => {
    db.serialize(function () {
    var cnt = 0
    db.each(`SELECT phone as phone, xp as xp, admin as admin, lastmsg as lastmsg, msgcount as msgcount FROM users`, (err, row) => {
    if (err) {
      console.error(err.message);
    }
    if (Object.is(row.phone, message.author)) {
      cnt++;
    }

    if (cnt > 0) {
      console.log(`Usuario ${message.author} já existe na database.`);
    } else {
      addContato(message.author);
    }

    console.log(message.author + " - " + row.phone + " - " + cnt)
   });
  });
 });
}

function addContato(autor) {
 db.serialize(function () {
  db.run(`INSERT INTO users (phone,xp,admin,lastmsg,msgcount) VALUES ("${autor}",0,0,0,0)`);
  console.log(`Usuário ${autor} adicionado a database.`);
 });
}

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