Using Promises in SQL query? - mysql

Question

I have an API call that requires some information to be fetched from MySQL database in order to fulfill the request. The problem is, NodeJS won't wait for query response and I have tried to solve this with Promises. Here is my code:
app.post('/placeOrder', async function (req, res) {
console.log(req.body.orderInfo);
var username = decryptAccessToken(req.body.AuthToken);
console.log(username);
var firstQuery = await fetchCustomerInfo(username, req.body.orderInfo);
con.query("INSERT INTO Orders SET ?", firstQuery, function (err, response) {
if (!err) {
console.log("Order successfully placed");
res.send("Order successfully placed");
} else {
console.log(err);
}
});
});
async function fetchCustomerInfo(username, orderInfo) {
return new Promise((resolve, reject) => {
con.query("SELECT FirstName, LastName, Address, Email, Phone FROM Customers WHERE Email=?", username, function (err, response) {
var createOrder = {
FirstName: response.FirstName,
LastName: response.LastName,
Address: response.Address,
Email: response.Email,
Phone: response.Phone,
ProductInfoJSON: orderInfo
}
console.log(createOrder);
resolve(createOrder);
})
})
}
This fetchCustomerInfo function will just return Promise object and that will trigger SQL syntax error, because that is not expected database input. What I'm doing wrong? Any advise is highly appreciated.
Update: SQL error has been solved with Murat's answer, but database query still returns undefined. I have made sure that the query works in console when used manually.

Answer 1

Try this:
app.post('/placeOrder', async function (req, res) {
var username = decryptAccessToken(req.body.AuthToken);
console.log(username);
var firstQuery = await fetchCustomerInfo(username, req.body.orderInfo);
con.query("INSERT INTO Orders SET ?", firstQuery, function (err, response) {
if (!err) {
console.log("Order successfully placed");
res.status(200).send("Order successfully placed");
} else {
console.log(err);
res.status(500).send("Error!");
}
});
});
function fetchCustomerInfo(username, orderInfo) {
return new Promise((resolve, reject) => {
con.query("SELECT FirstName, LastName, Address, Email, Phone FROM Customers WHERE Email=?", username, function (err, response) {
var createOrder = {
FirstName: response.FirstName,
LastName: response.LastName,
Address: response.Address,
Email: response.Email,
Phone: response.Phone,
ProductInfoJSON: orderInfo
}
console.log(createOrder);
resolve(createOrder);
})
})
}
Edit:
Since I have not had much experience with the MySql library, I did not check the accuracy of the function while writing the answer. However, the way you use con.query() is wrong. If you look at W3 Schools, this is the right way to use it.
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT * FROM customers", function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});