With an HTML5 game I am developing at the moment, I get the player's username and ID through a token sent in by the client which are all stored in a database. Everything was working perfectly up until I had to actually set the values for the player.
I've been searching all over the internet for similar problems that I am facing, and have come up with nothing. I am not sure if this is a variable scope problem or if I am taking the wrong approach to doing this.
Anyways, here's both the socket.player and getUserSession function
var newUserID;
var newUsersName;
socket.player = {
id: newUserID,
x: randomInt(100,400),
y: randomInt(100,400),
username: newUsersName
}
function getUserSession(sessionKey, callback){
var sql = "SELECT * FROM game_sessions WHERE unique_key=? AND still_active=?";
var stillActive = 1;
var returnData = [];
db.query(sql, [sessionKey, stillActive], function(err, result){
if (err){
throw err;
}
var numFound = result.length;
if (numFound == 1) {
//session was found
var userID = result[0].user_id;
returnData.push(result[0].user_id);
var sql2 = "SELECT * FROM users WHERE id=?";
db.query(sql2, [userID], function(err, result){
if (err){
throw err;
}
var uName = result[0].username;
returnData.push(result[0].username);
return callback(returnData);
});
}
});
}
And the callback function:
getUserSession(data.token, function(result){
newUserID = result[0];
newUsersName = result[1];
socket.broadcast.emit('newclient',socket.player);
});
I would do something like this:
function sqlQuery(sql, params) {
return new Promise((resolve, reject) => {
db.query(sql, params, function(err, result) {
if (err) {
return reject(err);
}
return resolve(result);
});
});
}
function getUserSession(sessionKey, callback){
const sql = "SELECT * FROM game_sessions WHERE unique_key=? AND still_active=?";
const stillActive = 1;
let returnData = [];
try {
return sqlQuery(sql, [sessionKey, stillActive])
.then(result => {
if (result.length === 1) {
//session was found
const userID = result[0].user_id;
returnData.push(result[0].user_id);
const sql2 = "SELECT * FROM users WHERE id=?";
return sqlQuery(sql2, [userID])
.then(result => {
const uName = result[0].username;
returnData.push(result[0].username);
return callback(returnData);
})
}
})
} catch (err) {
//handle err
}
}
Edit: if the callback function being passed in is an aync function, you'll probably need to modify the above snippet to await it.
Related
I am trying to run a query to get some data from a table, then use that array of data to get some data from another table to then return it as JSON.
I have been trying for a while but I cannot seem to figure out async and await. Right now it does sort of work but doesn't wait for my second query in the for loop to finish before returning data.
app.get("/get-top-trending", (request, response) => {
const req = request.query
let query = 'SELECT Ticker, Mentions FROM trend_data ORDER BY Date DESC, ' + req.by + ' DESC LIMIT 3';
let returnData = {};
cryptoDB.query(query, (err, tickers) => {
if (err) throw err;
getData(tickers).then(function() {
response.send(returnData)
});
});
async function getData(tickers) {
for (let i = 0; i < tickers.length; i++) {
cryptoDB.query('SELECT HistoricalJSON FROM historical_trend_data WHERE Ticker=? LIMIT 1', [tickers[i]['Ticker']], (err, rows2) => {
if (err) throw err;
returnData[tickers[i]['Ticker']] = rows2[0]['HistoricalJSON'];
});
}
}
});
I assume that something has to be done in the getData async function, however I am not particularly sure how to implement a working solution. I have tried promises but they don't seem to work the way that I expect.
Any guidance would be appreciated.
first solution:
app.get("/get-top-trending", (request, response) => {
const req = request.query
let query = 'SELECT Ticker, Mentions FROM trend_data ORDER BY Date DESC, ' + req.by + ' DESC LIMIT 3';
cryptoDB.query(query, (err, tickers) => {
if (err) throw err;
getData(tickers).then(function (returnData) {
response.send(returnData)
});
});
async function getData(tickers) {
const returnData = {};
const querys = ((ticker) => {
return new Promise((resolve, reject) => {
cryptoDB.query('SELECT HistoricalJSON FROM historical_trend_data WHERE Ticker=? LIMIT 1', [ticker['Ticker']], (err, rows2) => {
if (err) reject(err);
returnData[ticker['Ticker']] = rows2[0]['HistoricalJSON'];
resolve();
});
})
})
for (let i = 0; i < tickers.length; i++) {
await querys(tickers[i]);
}
return returnData
}
});
second solution:
app.get("/get-top-trending", (request, response) => {
const req = request.query
let query = 'SELECT Ticker, Mentions FROM trend_data ORDER BY Date DESC, ' + req.by + ' DESC LIMIT 3';
cryptoDB.query(query, (err, tickers) => {
if (err) throw err;
getData(tickers).then(function(returnData) {
response.send(returnData)
}).catch(error => throw error);
});
async function getData(tickers) {
let returnData = {};
for (let i = 0; i < tickers.length; i++) {
returnData[tickers[i]['Ticker']] = await getTickerQuery([tickers[i]['Ticker']]);
}
return returnData;
}
function getTickerQuery(ticker) {
return new Promise((resolve, reject) => {
cryptoDB.query('SELECT HistoricalJSON FROM historical_trend_data WHERE Ticker=? LIMIT 1', ticker, (err, rows2) => {
if (err) throw reject(err);
resolve(rows2[0]['HistoricalJSON']);
});
})
}
});
I recommend second solution for readability
Small problem when using POST and adding an INSERT. Works as below, but want to use a callball after the data has been inserted. At the moment the database is being updated. (good) but can't use the callback - I would expect this to be just below the throw error. So you could use result.insertId. Any thoughts welcome?
router.post('/group/:id', function(req, res) {
var idToken = req.params.id;
admin.auth().verifyIdToken(idToken).then(function(decodedToken) {
var userID = decodedToken.uid;
var name = encrypt(req.body.group);
getID(userID, function(result){
var ID = result;
var post = {ID:ID, name:name};
db.query('INSERT INTO cu_groups SET ?', post, function (error, results, fields) {
if (error)throw error;
//*** when I add response here get 502 bad gateway error.
});
res.sendStatus(200);
}); // depends on getID
// admin.auth cat
}).catch(function(error) {
res.sendStatus(error);
});
});
try this way :
router.post('/group/:id', function(req, res) {
var idToken = req.params.id;
admin.auth().verifyIdToken(idToken).then(function(decodedToken) {
var userID = decodedToken.uid;
var name = encrypt(req.body.group);
getID(userID, function(result){
var ID = result;
var post = {ID:ID, name:name};
db.query('INSERT INTO cu_groups SET ?', post, function (error, results, fields) {
if(error){
return res.status(500).send(error);
}
if(!error && results){
return res.status(200).send(results);
}
});
});
}).catch(function(error) {
return res.status(500).send(error);
});
});
if you want to use callback then ,create a separate function like :
var insertData = function(query,data,callback){
db.query(query, data, function (error, results, fields) {
if(error){callback(error,null);}
if(!error && results){callback(null,results);}
});
});
and call this way inside getID :
getID(userID, function(result){
var ID = result;
var post = {ID:ID, name:name};
insertData('INSERT INTO cu_groups SET ?', post, function (error,data){
if(error){
return res.status(500).send(error);
}
if(data){
return res.status(200).send(data);
}
});
});
Working code below many thanks to Saurabh Mistry. I removed the SET post and added the table fields and values explicity.
router.post('/group/:id', function(req, res) {
var idToken = req.params.id;
admin.auth().verifyIdToken(idToken).then(function(decodedToken) {
var userID = decodedToken.uid;
var name = encrypt(req.body.group);
getID(userID, function(result){
var ID = result;
// query
let query = "INSERT INTO cu_groups (ID, name) VALUES('" + ID + "','" + name + "')";
// execute query
db.query(query, (error, result) => {
if(error){
return res.status(500).send(error);
}
if(!error && result ){
return res.send(result);
}
});
}); // depends on getID
// admin.auth cat
}).catch(function(error) {
return res.status(500).send(error);
});
});
I want to return database value in node js and pass as a variable in ejs file.
Bellow is the code, Which I used. it did not return value.
function getExternalLocation(cb) {
mssql.connect(msSqlSettings, function (err ) {
if (err) {
cb(err);
}
var getQuery = "SELECT [Title] FROM [dbo].[StyleTemplates] " ;
//console.log(getQuery);
var request = new mssql.Request();
// query to the database and get the data
request.query(getQuery, function (err, rows) {
mssql.close();
cb(err, rows);
});
});
}
exports.eejsBlock_editbarMenuLeft = function (hook_name, args, cb) {
var userData = getExternalLocation(args, function(err, rows) {});
args.content = args.content + eejs.require(
'ep_resources/templates/editbarButtons.ejs', {
userData: userData
});
return cb();
})
userData did not return any value.
var userData = getExternalLocation(args, function(err, rows) {});
I don't think userData will get right data in async function, there is no await, so you can try to get data in callback.
getExternalLocation(args, function(err, rows) {
var userData = rows;
args.content = args.content + eejs.require(
'ep_resources/templates/editbarButtons.ejs', {
userData: userData
});
});
I want to separate the code for executing mysql query in Node, so I am trying to use the Revealing Module pattern here
/* pool -create connection pool mysql*/
var sqlQuery = function (sqlString) {
var _result = pool.getConnection(function (err, connection) {
/* error handling*/
connection.query(sqlString, function (err, rows) {
console.log(this.sql);
if (!err) {
return _result = rows; <============
}
connection.release();
});
return;
});
console.log(_result);
return { recordSet : _result }
};
module.exports = sqlQuery;
How can I return rows to my app.js. the code below for calling sqlQuery is not working
var SqlQuery = require(./path/to/sqlQueryFile);
var rows = SqlQuery('pass sql here').recordSet;
console.log(row);
res.json(rows);
Your code is asynchronous, but you're calling it synchronously.
If you wanted to do it like this, you'll also need to pass a callback to SqlQuery.
/* pool -create connection pool mysql*/
var sqlQuery = function (sqlString, callback) {
var _result = pool.getConnection(function (err, connection) {
/* error handling*/
connection.query(sqlString, function (err, rows) {
console.log(this.sql);
if (!err) {
callback(rows);
}
connection.release();
});
});
};
module.exports = sqlQuery;
And then call it with:
var SqlQuery = require(./path/to/sqlQueryFile);
var rows = SqlQuery('pass sql here', function(recordSet){
console.log(recordSet);
res.json(recordSet);
});
Edit: If you're using newer versions of JavaScript, you have a few more options.
If you have access to Promises, you can do this:
function sqlQuery (sqlString) {
return new Promise((resolve, reject) => {
pool.getConnection(function (err, connection) {
if (err) { return reject(err); } // error handling
connection.query(sqlString, function (err, rows) {
if (err) { return reject(err); }
resolve(rows);
connection.release();
});
});
});
}
module.exports = sqlQuery;
And then you'd use it like:
var SqlQuery = require(./path/to/sqlQueryFile);
SqlQuery('pass sql here')
.then(function(recordSet) {
console.log(recordSet);
res.json(recordSet);
})
.catch(function(err) {
// do your error handling
res.status(500).json({ err: 'Sorry there was an error' });
});
If you're using even newer JavaScript, you can use the async/await syntax (currently available via Babel, and I think in FireFox. Chrome in V55).
var SqlQuery = require(./path/to/sqlQueryFile);
async handleQuery(query) {
try {
var rows = await SqlQuery(query);
res.json(rows);
} catch (e) {
console.log('Error!', e);
}
}
To chain multiple queries together:
async handleQuery(query) {
try {
return await SqlQuery(query);
} catch (e) {
console.log('Error!', e);
}
}
var rows = await handleQuery('select * from tablename');
var rowsToReturn = await handleQuery('select id from another_table where name = "' + rows[0].name + '"');
I need to do this to log into SalesForce Databases and pass a query. Now I will be passing a lot of queries on many routers of express.js and its a real pain to login in every router. Please let me know if you know how I can avoid this.
var conn = new jsforce.Connection({
oauth2 : salesforce_credential.oauth2
});
var username = salesforce_credential.username;
var password = salesforce_credential.password;
// I want to avoid this login on every router
conn.login(username, password, function(err, userInfo) {
if (err) {
return console.error(err);
}
conn.query("SELECT id FROM Sourcing__c WHERE id = 'req.session.ref'",function(err, result) {
if (err) {
return console.error(err);
}
if(result.records.length === 0){
req.session.ref = "";
}
var body = {
"Auth__c": req.user.id,
"Stus__c": "Pending - New Hire",
"Record": "012lvIAC",
"Sourcing__c": req.session.ref
};
conn.sobject("SFDC_Employee__c").create(body, function(err, ret) {
if (err || !ret.success) {
return console.error(err, ret);
}
console.log("Created record id : " + ret.id);
// ...
});
});
});
You may save the login status and check it every time when do a query,
here I add a property on conn (the instance of 'jsforce.Connection'), I'm not sure but I think there may be a method or property that show the login status of the 'conn', you may dig into its documents.
var conn = new jsforce.Connection({
oauth2 : salesforce_credential.oauth2
});
var username = salesforce_credential.username;
var password = salesforce_credential.password;
conn._isLogin = false;
// here in your route handler
if (!conn._isLogin) {
conn.login(username, password, function(err, userInfo) {
if (err) {
return console.error(err);
}
conn._isLogin = true;
doQuery(conn);
});
} else {
doQuery(conn);
}
function doQuery (conn) {
conn.query("SELECT id FROM Sourcing__c WHERE id = 'req.session.ref'",function(err, result) {
if (err) {
return console.error(err);
}
if(result.records.length === 0){
req.session.ref = "";
}
var body = {
"Auth__c": req.user.id,
"Stus__c": "Pending - New Hire",
"Record": "012lvIAC",
"Sourcing__c": req.session.ref
};
conn.sobject("SFDC_Employee__c").create(body, function(err, ret) {
if (err || !ret.success) {
return console.error(err, ret);
}
console.log("Created record id : " + ret.id);
// ...
});
});
}