Can't return an array. At the exit you need to get each value separately to insert into the database. Maybe somewhere I made a mistake with the callback. Code below.
function executeTest(connection, callback) {
var results = [];
var request = new Request(ted_select, function(error) {
if (error) {
return callback(error);
}
// pass the results array on through the callback
callback(null, results);
});
request.on("row", function(rowObject) {
// populate the results array
results.push(rowObject);
});
connection.execSql(request);
}
function test(callback) {
var connection = new Connection(config);
connection.on('connect', function(err) {
if (err) {
console.log(err);
} else {
console.log('Connect database');
executeTest(connection, function(error, results) {
// here is the results array from the first query
console.log(results);
});
setTimeout(function(){connection.close(console.log('Disconnect database'));},10000);
}
callback(null, results);
});
}
var value = test();
console.log(value);
Thanks.
Related
getting undefined all the time "main.js":
var dbAccess = require('../dao/dbAccess');
dbaInstance = new dbAccess();
var wordPool = dbaInstance.getWordPool();
console.log (wordPool);
and "dbAccess.js" contains:
var DatabaseAccess = function() {}
DatabaseAccess.prototype.getWordPool = function () {
RoundWord.find({},'words decoys', function(err, wordPoolFromDB) {
if (err) throw err;
//console.log(wordPoolFromDB); -working ok
return (wordPoolFromDB);
});
}
module.exports = DatabaseAccess;
why is it not working?
DatabaseAccess.prototype.getWordPool is not returning any result.
Since you are using an asynchronous function, you need do one of these things:
a) Take a callback as parameter and invoke the callback with a result
DatabaseAccess.prototype.getWordPool = function (cb) {
RoundWord.find({}, 'words decoys', function(err, results) {
if (err) {
return cb(err, null);
}
cb(null, results);
});
}
The callback convention is: cb(error, results...)
b) Use promises
DatabaseAccess.prototype.getWordPool = function () {
return RoundWord.find({}, 'words decoys', function (err, results) {
if (err) {
throw err; // however you might want to sanitize it
}
return results;
});
}
To consume this result you will need to do it as a promise
databaseAccess.getWordPool()
.catch(function (err) {
// process the error here
})
.then(function (results) {
// something with results
});
It will work if you change to this:
var dbAccess = require('../dao/dbAccess');
dbaInstance = new dbAccess();
dbaInstance.getWordPool(function(wordPool){console.log (wordPool);});
And:
var DatabaseAccess = function() {}
DatabaseAccess.prototype.getWordPool = function (cb) {
RoundWord.find({},'words decoys', function(err, wordPoolFromDB) {
if (err) throw err;
//console.log(wordPoolFromDB); -working ok
cb(wordPoolFromDB);
});
}
module.exports = DatabaseAccess;
If the function is Asynchronous you need to pass a callback to find to get the result:
DatabaseAccess.prototype.getWordPool = function (callback) {
RoundWord.find({},'words decoys', function(err, wordPoolFromDB) {
if (err) throw err;
callback(err, wordPoolFromDB);
});
}
and call it as follows in main:
dbaInstance.getWordPool(function (err, wordPool) {
console.log (wordPool);
// wordPool is only available inside this scope,
//unless assigned to another external variable
});
// cannot access wordPool here
I have search function that receive string from client, so once loop process is done sending matching results to client using callback. With below code two issues
1-first time when i have search string it sends the response results but when
2- second if i search different string it sends empty array of results
3- if i search first string again i get the response
Any idea what is implemented wrong in below code.
app.js
app.get('/serverSearch', function (req, res) {
var searchTxt = req.query.searchTxt;
dirDirectory.readDirectory(function(logFiles){
// res.json(logFiles);
if(logFiles){
searchFileService.readFile(searchTxt,logFiles,function(lines,err){
console.log('Logs',lines);
if (err)
return res.send();
res.json(lines);
})
}
});
console.log('Search text', searchTxt);
});
searchService.js
var results = [];
var searchStr;
function readFile(str, logFiles, callback) {
searchStr = str;
// loop through each file
async.eachSeries(logFiles, function (logfile, done) {
// read file
fs.readFile('logs/dit/' + logfile.filename, 'utf8', function (err, data) {
if (err) {
return done(err);
}
var lines = data.split('\n'); // get the lines
lines.forEach(function(line) { // for each line in lines
if (line.indexOf(searchStr) != -1) { // if the line contain the searchSt
results.push(line);
}
});
// when you are done reading the file
done();
});
// wrong: }), function (err) {
}, function (err) {
if (err) {
console.log('error', err);
}
console.log('all done: ', results);
// wrong: results.map(result, function (result){
results.map(function (result){
console.log(result);
});
// send back results
callback(results);
results = [];
});
}
I'm using mssql(Microsoft SQL Server client for Node.js) package from npm.I'm trying to execute a stored procedure residing in my sql server database.Everything works fine.However what I want to do is return the recordsets so that i can export this to be used in other module.Below is what I'm trying to do.
function monthlyIceCreamSalesReport (scope){
var connObj = connConfig();
connObj.conn.connect(function(err){
if(err){
console.log(err);
return;
}
connObj.req.input('Month',4);
connObj.req.input('Year',2016);
connObj.req.execute('<myStoredProcedure>', function(err, recordsets, returnValue){
if(err){
console.log(err);
}
else {
console.log(recordsets[0]); // successfully receiving the value
}
connObj.conn.close();
});
});
console.log('check for recordsets', recordsets[0]); // undefined
return recordsets[0];
}
var sqlServerObj = {
monICSalesReport : monthlyIceCreamSalesReport,
};
module.exports = sqlServerObj;
As shown in the code snippet, since the value of recordsets[0] is undefined, exporting this function is of no use.
You can't return this way in async nature. You can get it by passing the callback function
Try to give a callback function like this
function monthlyIceCreamSalesReport(scope, callback) { // pass a callback to get value
var connObj = connConfig();
connObj.conn.connect(function(err) {
if (err) {
console.log(err);
return;
}
connObj.req.input('Month', 4);
connObj.req.input('Year', 2016);
connObj.req.execute('<myStoredProcedure>', function(err, recordsets, returnValue) {
if (err) {
console.log(err);
} else {
console.log(recordsets[0]);
connObj.conn.close();
return callback(null, recordsets[0]); //return as a callback here and get that value in callback from where you called this function
}
});
});
}
var sqlServerObj = {
monICSalesReport: monthlyIceCreamSalesReport,
};
module.exports = sqlServerObj;
Note: See the comment to understand the changes
recordsets[0] is undefinded, because is defined only in connObj.req.execute function scope. You may do this in this way:
function monthlyIceCreamSalesReport (scope, cb){
var connObj = connConfig();
connObj.conn.connect(function(err){
if(err){
console.log(err);
return cb(Error("Something wrong"));
}
connObj.req.input('Month',4);
connObj.req.input('Year',2016);
connObj.req.execute('<myStoredProcedure>', function(err, recordsets, returnValue){
if(err){
console.log(err);
connObj.conn.close();
return cb(Error("Something wrong"));
}
else {
console.log(recordsets[0]); // successfully receiving the value
connObj.conn.close();
return cb(recordsets[0]);
}
});
});
}
var sqlServerObj = {
monICSalesReport : monthlyIceCreamSalesReport,
};
module.exports = sqlServerObj;
I'm getting an array of objects from mongoDB and I'm having trouble dissecting each object in the array by its properties. Basically I would like to get a certain subdocument and get its intersection then assign scores per index per intersection.
Here's my code so far:
exports.draft = function(req,res) {
if(req.session.fb_id) fb_id = req.session.fb_id;
function getUserQuery (fb_id) {
//Get user
}
function getAllUsersQuery (prefs, callback) {
//Get all users in database from user preferences
}
function getUserTracks (callback) {
var query = getUserQuery;
query.exec(function(err,tracks){
callback(null, cu.tracks);
})
}
function getInitialMatches (cuPrefs, callback) {
var query = getAllUsersQuery(cuPrefs, callback);
query.exec(function(err, users) {
if(err) console.log("ERROR retrieving filtered users ---> " + err);
callback(null, users);
});
}
function mapInitialMatch (initMatch, callback) {
var temp = {
name: initMatch.name,
tracks: initMatch.tracks
};
callback(null, temp);
}
var asyncInitMatches = function (callback) {
async.waterfall([
async.apply(getPreferences),
function (cuPrefs, callback) {
getInitialMatches(cuPrefs, callback);
},
function (initialMatches, callback) {
async.map(initialMatches, mapInitialMatch, function (err, results) {
if(err) console.log("ERROR in mapping user" + err);
callback(null, results);
});
}
], function(err, results){
if(err) console.log('------> ERROR in asyncInitMatches --> ' + err);
callback(null, results);
});
};
async.parallel([
async.apply(getTracks),
async.apply(asyncInitMatches)
], function(err, results) {
userTracks = results[0];
matchesTracks = results[1];
//I would like to get the intersection of userTracks and matchesTracks[i]
});
}
Sample userTracks:
userTracks = {
"name": "Sample Name",
"tracks": [{
"id": _id,
"name": "Track name"
}]
}
I'm always getting a null/undefined result when I show it in the console. I'm also trying to use underscore.js (map, pluck, intersection). Also can you help me understand async.map and async.each?
THANK YOU!
Pretty sure this is a quite noobish node.js/callback question but I can't seem to find the proper code to make it run.
This is how I invoke my node-mysql code:
var utils = require('../../config/database/utils');
exports.getResults = function(callback) {
var query = "SELECT * FROM my_table";
utils.exec(query, null, function(err, results){
if(err){
console.log(err);
callback(true);
return;
}
console.log(results);
callback(false, results);
});
};
Next is the utils file where I can't get the code work.
var pool = require('./connection');
module.exports = {
getDBConnection: function() {
pool.getConnection(function(err, connection){
if(err){
console.log(err);
return;
}
return connection;
});
},
endDBConnection: function(connection) {
connection.end(function (err) {
if(err) {
console.log(err);
callback(true);
return;
}
});
},
exec: function(query, data, callback) {
console.log(query);
this.getDBConnection(function(err, connection){
if(err){
console.log('error');
}
console.log(connection);
connection.query(query, data, function(err, results) {
if(err) {
callback(err);
}
callback(false, results);
});
this.endDBConnection(connection);
});
}
}
Code is getting OK the the exec part since the console.log(query) logs the query. But after that, the code's not running, console.log(connection); doesn't show a thing, and of course the connection.query is also not running.
I'm not sure why this is happening.
Returning a value inside a callback is meaningless. You need to pass in a callback that gets called with the value you want to return:
getDBConnection: function(callback) {
pool.getConnection(function(err, connection){
if(err){
console.log(err);
return callback(err);
}
callback(null, connection);
});
},
You should also use connection.release() instead of connection.end() since you are using a pool:
endDBConnection: function(connection) {
connection.release();
},
In exec(), you have the wrong this. It should instead be something like:
exec: function(query, data, callback) {
console.log(query);
var self = this;
this.getDBConnection(function(err, connection){
if(err){
console.log('error');
return callback(err);
}
console.log(connection);
connection.query(query, data, function(err, results) {
self.endDBConnection(connection);
if(err) {
return callback(err);
}
callback(null, results);
});
});
}