I have problem in calling the method in my module.
There is an errorTypeError: usr.User.getAddress is not a function
I don't know how to fix this I think I have problem in my module code. I want to get the address or the result.
in my main.js
var mysql = require('mysql');
var usr = require('./user');
var useraddress = usr.User.getAddress (id,pool); //this is how I access the method
in my user.js
exports.User = function () {
return {
getAddress: function (userid, pool){
pool.getConnection(function (err, connection) {
var options = {
sql: " select address from user where id = ?
};
var querypos = connection.query(options, [userid], function (err, results) {
if (err) throw err;
});
});
}
};
};
You are exporting User as a factory function which returns an object with getAddress method on it. So you need to invoke (instantiate) User first:
var useraddress = usr.User().getAddress(id, pool);
Another important problem. connection.query request is asynchronous, which means that assigning getAddress result to var useraddress doesn't make sense. Instead you need to either pass callback to getAddress or use Promise pattern (check this post for great deal of details on the topic: How do I return the response from an asynchronous call?).
In your case I think something like this would be a simplest working approach:
exports.User = function () {
return {
getAddress: function (userid, pool){
pool.getConnection(function (err, connection) {
var options = {
sql: "select address from user where id = ?"
};
var querypos = connection.query(options, [userid], function (err, results, callback, errCallback) {
if (err) {
errCallback(err);
}
callback(results);
});
});
}
};
};
and usage:
usr.User().getAddress(id, pool, function(result) {
console.log('Loaded', result);
});
This is because usr.User does not have .getAddress property on it.
To use .getAddress as a property, you need to export User as an object instead.
exports.User = {
getAddress: function (userid, pool){
pool.getConnection(function (err, connection) {
var options = {
sql: " select address from user where id = ?
};
var querypos = connection.query(options, [userid], function (err, results) {
if (err) throw err;
});
});
}
};
};
Now it does.
Related
This question already has answers here:
How do I return the response from an asynchronous call?
(41 answers)
Closed 6 years ago.
I want to assign data return from the model, then on console.log i only see
undefined
My code is:
var dmodel = require('../models/database');
dmodel.myfunction(request,response, function (err, user) {
console.log(user); // see data
});
Then I repair code:
var dmodel = require('../models/database');
var userinfo;
dmodel.myfunction(request,response, function (err, user) {
userinfo = user;
});
console.log(userinfo); // undefined, not see data
How do it ? Thanks all
This is my function:
module.exports = {
myfunction: function (request,response, callback) {
var query = "select * from mytable";
//call functionexcecute query
executeQuery(query, function (err, rows) {
if (!err) {
var user = rows;
callback(null, user);
} else {
console.log(err);
}
});
}
};
Due to asynchronous nature of javascript, code console.log(userinfo) is getting executed before the callback function is called.
Modified code:
var dmodel = require('../models/database');
var userinfo;
dmodel.myfunction(request,response, function (err, user) {
userinfo = user;
console.log(userinfo);
});
That is, your earlier code was correct. If the value printed is still undefined, that means there is some issue with the definition of function executeQuery.
you can use a .then promise which will wait for the first function to complete its execution
var dmodel = require('../models/database');
var userinfo= {};
dmodel.myfunction(request,response, function (err, user) {
userinfo = user;
return userinfo;
}).then(function(data){
console.log(userinfo);
})
I am currently trying to run a set of MySQL query's in order using async.js series control flow function. But I keep receiving the following error:
throw err; // Rethrow non-MySQL errors
^
TypeError: Cannot read property 'status' of undefined
I have tested the query's in seperate functions outside the async.series and they are fine and give me back the data, the only reason I can think for the error is due to the async nature it doesn't have the data at that time hence the error E.G when I log the rows I get:
[]
[]
[]
Below is the Async function:
function SQLuserDataAsync() {
connection.getConnection(function (err, connection) {
async.series([
function (callback) {
connection.query('SELECT status FROM users WHERE name= ?;',
[userval],
function (err, rows) {
if (rows[0]['status']) {
console.log("Account Status: " + accountval);
} else {
console.log(err);
}
callback(null, 'one');
});
},
function (callback) {
connection.query('SELECT account_type FROM settings_tbl WHERE id=(SELECT id FROM users WHERE name= ?);',
[userval],
function (err, rows) {
if (rows[0]['account_type']) {
var acctype = rows[0]['account_type'];
console.log("Account Type: " + acctype);
} else {
console.log(err);
}
callback(null, 'two');
});
},
function (callback) {
connection.query('SELECT type FROM settings_tbl WHERE id=(SELECT id FROM users WHERE name= ?);',
[userval],
function (err, rows) {
if (rows[0]['type']) {
var type = rows[0]['type'];
console.log("Type: " + type);
} else {
console.log(err);
}
callback(null, 'three');
});
}
]);
connection.release();
});
}
Any suggestions as the reason for the error or what am doing wrong here?
You've missed the main callback function to the async.series function.
function SQLuserDataAsync() {
connection.getConnection(function (err, connection) {
async.series([
function (callback) {
// YOUR CODE
},
function (callback) {
// YOUR CODE
},
function (callback) {
// YOUR CODE
}
], function(error, results) { // <--- this is the main callback
connection.release();
});
});
}
You should call connection.release() inside the main callback, otherwise, the MySQL connection will be released/terminated before the queries are executed (due to the asynchronous nature the code).
if there is a user with defined in userval name it will work.
But let's simplify our code:
function SQLuserDataAsync(userval) {
connection.getConnection(function (err, connection) {
async.waterfall([
// getting user
function (next) {
connection.query(
'SELECT * FROM users WHERE name = ? LIMIT 1',
[userval],
function (err, result) {
next(err, result[0]); // passing user to next function
});
},
// getting settings of user, maybe user_id (not id) in query below
function (user, next) {
connection.query(
'SELECT * FROM settings_tbl WHERE id = ? LIMIT 1',
[user.id],
function (err, result) {
next(err, user, result[0]);
});
},
// handling both user and settings
function (user, settings, next) {
console.log('User: ', user);
console.log('Settings: ', settings);
connection.release();
}
]);
});
}
SQLuserDataAsync('someone');
I'm trying to check the entered username and password stored in a database.
My solution is not correct and I think there might be something better than my code.
Here it is thus far:
function login (username, password, callback) {
var query = "SELECT * FROM users WHERE username = ?";
connection.query(query, [username], function (err, results) {
if (err) return callback(err);
if (results.length === 0) return callback();
var user = results[0];
if (!bcrypt.compareSync(password, user.password)) {
return callback();
}
callback(null, {
id: user.id.toString(),
});
});
}
app.get('/salam', function (req, res) {
var username = 'mahdi';
var originalPassword = 'a';
login(username , originalPassword,function (callback) {
console.log(callback);
});
});
In my code, console.log(callback); returns null, but usernames and passwords are correct. How can I fix this?
In your success callback function, you are having 2 arguments but in error callback, only one argument.
In error and success case, value of first parameter will always be null and in if (!bcrypt.compareSync(password, user.password)) { case, value of first argument will be undefined as there is no value being passed as argument.
Suggestion: Use first argument as Boolean(false or true) and based on the value, handle the callback.
function login(username, password, callback) {
var query = "SELECT * FROM users WHERE username = ?";
connection.query(query, [username], function(err, results) {
if (err) return callback(false);
if (results.length === 0) return callback();
var user = results[0];
if (!bcrypt.compareSync(password, user.password)) {
return callback(false);
}
callback(true, {
id: user.id.toString(),
});
});
}
app.get('/salam', function(req, res) {
var username = 'mahdi';
var originalPassword = 'a';
login(username, originalPassword, function(success, value) {
if (success) {
console.log(value);
}
});
});
It should be, because you didn't pass anything in callback. Change like this :
function login (username, password, callback) {
var query = "SELECT * FROM users WHERE username = ?";
connection.query(query, [username], function (err, results) {
if (err) return callback(err);
if (results.length === 0) return callback(null, false);
var user = results[0];
if (!bcrypt.compareSync(password, user.password)) {
return callback(null, false);
}
callback(null, true, {
id: user.id.toString(),
});
});
}
app.get('/check', function (req, res) {
var username = 'mahdi';
var originalPassword = 'a';
login(username , originalPassword,function (err, result, id) {
console.log(err);
console.log(result);
console.log(id);
});
});
result is for finding out true|false of action. And id means when result is true
Also err for callback is needed to error handling
I understand well the concepts of OOP and prototypal inheritance in JavaScript, but sometimes, I wonder how to make use of these in real world applications.
I'll take as an exemple a simple(istic) contact management web application I pushed on GitHub a couple of months ago.
In the main handler mainly reside functions:
var UserModel = require('../models/userModel.js');
var checkObjectId = new RegExp('^[0-9a-fA-F]{24}$');
var root;
exports.getContacts = function(request, response) {
var id = JSON.parse(request.params.user)[0];
// validate
if (!checkObjectId.test(id)) {
return res.status(400).json({error: 'Not a user id'});
}
UserModel.findById(id, function(err, user) {
if (err) {
return console.log(err);
}
response.send(user.contacts);
});
};
exports.addContact = function(request, response) {
var id = JSON.parse(request.params.user)[0];
// validate
if (!checkObjectId.test(id)) {
return res.status(400).json({error: 'Not a user id'});
}
UserModel.findById(id, function(err, user) {
if (err) {
return console.error(err);
}
var contact = {};
// avoid to save empty info
if (request.body.first.length > 1) {contact.first = request.body.first;}
if (request.body.last.length > 1) {contact.last = request.body.last;}
if (request.body.mobile.length > 1) {contact.mobile = request.body.mobile;}
if (request.body.home.length > 1) {contact.home = request.body.home;}
if (request.body.office.length > 1) {contact.office = request.body.office;}
if (request.body.email.length > 1) {contact.email = request.body.email;}
if (request.body.company.length > 1) {contact.company = request.body.company;}
if (request.body.description.length > 1) {contact.description = request.body.description;}
if (request.body.keywords.length > 1) {contact.keywords = request.body.keywords;}
user.contacts.push(contact);
user.save(function(err) {
if (err) {
return console.error(err);
}
console.log('contact saved');
response.send(user.contacts);
});
});
};
exports.updateContact = function(request, response) {
var id = JSON.parse(request.params.user)[0];
// validate
if (!checkObjectId.test(id)) {
return res.status(400).json({error: 'Not a user id'});
}
var contact = {
_id: request.body._id,
first: request.body.first,
last: request.body.last,
mobile: request.body.mobile,
home: request.body.home,
office: request.body.office,
email: request.body.email,
company: request.body.company,
description: request.body.description,
keywords: request.body.keywords
};
UserModel.update({_id: id, "contacts._id": request.body._id}, {$set: {"contacts.$": contact}}, function(err, user) {
if (err) {
return console.error(err);
}
response.sendStatus(user);
});
};
exports.deleteContact = function(request, response) {
var id = JSON.parse(request.params.user)[0];
// validate
if (!checkObjectId.test(id)) {
return res.status(400).json({error: 'Not a user id'});
}
return UserModel.update({_id: id}, {$pull: {contacts: {_id: request.params.id}}}, function(err, user) {
if (err) {
return console.error(err);
}
console.log('contact removed');
console.log(user);
response.sendStatus(user);
});
};
It doesn't do much: fetch data from DB and return them or take data from user and save them to DB.
If it was a bit more complexe, I would surely place some logic in separate functions to reuse them and break down complexity.
Nevertheless, this code looks rather procedural, so does the hypothetical more complex version with separate functions. How would it be organized in a OOP way and how would I gain from it?
For instance, would I benefit from a User constructor?
I think the first thing you could do is nest the instance of your constructor inside an initializing function so you wouldn't have to repeat your validation code.
var connection = (function() {
var UserModel = require('../models/userModel.js');
var notAUser = {error: 'Not a user id'};
function init(request, response) {
var status = validate(JSON.parse(request.params.user)[0]);
if (!status.id) return response.status(400).json(status);
return new Connect(request, response, status.id);
}
function Connect(request, response, id) {
this.request = request;
this.response = response;
this.id = id;
this.info = { _id: id, "contacts._id": request.body._id };
}
function validate(id) {
if (!/^[0-9a-fA-F]{24}$/.test(id)) return notAUser;
else return {id: id};
}
Connect.prototype.getContact = function() {}
//etc...
return init;
})();
module.exports = connection;
Then in your actual application
var connection = require("./connection.js");
someAsync(data, function(req, res) {
var query = connection(req, res); //returned instance of constructor
query.getContact(someData, callback);
});
I would start by encapsulating the request and response since every method needs those. Like:
var contact = function (request, response) {
return {
add: add
}
function add() {
// add() gets access request and response for free
}
};
OR, if you are keen on the new operator:
function Contact(request, response) {
this.request = request;
this.response = response;
}
Contact.prototype.add = function () {
this.request;
}
Then move repeated code and callbacks to private methods you can reuse inside the object.
I'm new to expressJS and i'm wondering what is the best way to requery the database (mongo in my case) to get all the records after one is added.
exports.get = function (db) {
return function (req, res) {
var collection = db.get('notes');
collection.find({}, {}, function (e, docs) {
res.send(docs);
});
};
};
exports.create = function (db) {
return function (req, res) {
var title = req.body.title;
var note = req.body.note;
var collection = db.get('notes');
// Insert/update the note
collection.insert(
{
"title": title,
"note": note
},
function (err, doc) {
// If it failed, return error
if (err) {
res.send("There was a problem adding the information to the database. Error: "+err);
} else {
//res.redirect('/');
//res.json(db.get('notes'));
// WHAT IS THE BEST THING TO DO HERE TO GET ALL THE RECORDS INCLUDING THE ONE I'VE JUST ADDED?
exports.get(db);
}
}
);
}
};
I would replace
exports.get(db);
for
collection.find({}, {}, function (e, docs) {
res.send(docs);
});
The reason is that you are invoking this in the callback, AFTER the record has been inserted
Your exports.get function return a function, a kind of middleware I see.
Repplace
exports.get(db);
by
exports.get(db)();