无法在Express响应中发送对象

Question

I'm trying to send all the data from my database back using res.send, but it's throwing me an error. On my frontend, I'm calling the endpoint select and trying to return all rows and data within the database.

app.get('/select', function (req, res) {
    con.query('SELECT * FROM Contracts', function (err, rows, fields) {

    if (err) {
      console.log(`Error: ${err}`);
    }

    for (var i = 0; i < rows.length; i++) {
      var row = rows[i];
      res.send(row);
    }
  })
});

Answer 1

You should use res.write instead of res.send as the latter terminates the function (nothing after the first use of res.send is executed)

app.get('/select', function (req, res) {
    con.query('SELECT * FROM Contracts', function (err, rows, fields) {

    if (err) {
      console.log(`Error: ${err}`);
    }

    for (var i = 0; i < rows.length; i++) {
      var row = rows[i];
      res.write(row);
    }
    res.end(); //this finally sends the response
  })
});

Or if you want to use res.send send the whole rows array:

app.get('/select', function (req, res) {
    con.query('SELECT * FROM Contracts', function (err, rows, fields) {

    if (err) {
      console.log(`Error: ${err}`);
    }

    res.send(rows);
  })
});