在 Node.js MySQL 中等待查询

Question

When I run this right now the page renders before it can receive the data from MySQL. The loop goes for all the files in a folder and finds that data in the How can I make it wait for the data to be sent before loading the webpage?

app.get('/explore', function(req,res){
  var fileNames = new Array();
    pool.getConnection(function(err, connection) {
      fs.readdirSync('./files').forEach(file => {
        if (err) throw err;
        var requester = "SELECT * FROM files WHERE dbname = '" + file + "'";
        pool.query(requester, function (err, result) {
          if (err) throw err;
          fileNames.push(result[0].name);
        });
        connection.release();
      });
    });
  res.render('explore', { fileNames : fileNames })
});

Answer 1

You can make minor corrections in the code so that it renders as intended.

app.get('/explore', function(req,res){
  var fileNames = new Array();
    pool.getConnection(function(err, connection) {
      fs.readdirSync('./files').forEach(file => {
        if (err) throw err;
        var requester = "SELECT * FROM files WHERE dbname = '" + file + "'";
        pool.query(requester, function (err, result) {
          if (err) throw err;
          fileNames.push(result[0].name);
          res.render('explore', { fileNames : fileNames })
          //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
        });
        connection.release();
      });
    });
});