I have written the following code, it's for a discord bot. When I call the command I get matchID in console for the first time. But when I call the command again I dont get any output. It gets stuck near the point where I have console.log("Stuck Here"). I new to mongoose so I don't know what to do.
if (mongoose.connection.readyState === 0) {
mongoose.connect(`mongodb://localhost/${server}`, {
useNewUrlParser: true
});
console.log('mongoose readyState is ' + mongoose.connection.readyState);
}
console.log("Stuck here!");
mongoose.connection.on("error", function (err) {
console.log("Could not connect to mongo server!");
return console.log(err);
});
mongoose.connection.on('connected', function (ref) {
console.log('Connected to mongo server.');
mongoose.connection.db.listCollections({
name: "matches"
}).next(function (err, collinfo) {
if (err) console.log(err);
if (collinfo) {
Matches.findOne({}, {}, {
sort: {
'created_at': -1
}
}, function (err, match) {
if (err) console.log(err);
console.log(`${match.matchID}`);
})
} else {
}
});
})
Mongoose is really meant to be used with a single database. It isn't impossible to create create multiple connections, or use multiple database, but it's not trivial either. For instance, you have to declare each of your models for each connection/database (see this answer, for instance).
It's probably much easier to use a single database, and adjust your models so they contain a property server that you can use as a key in all your queries.
So to check if there's a Matches document for server "X", you'd run Matches.findOne({ server : 'X' }).
You could also consider creating a separate model Servers that would store metadata for servers, and use references between the Matches and Servers models. More info on that here.
Related
I’m trying to connect to a database through node. I’ve got it working with smaller databases using a Mongo URL of the form:
mongodb://[username]:[password]#db1-a0.example.net:27017/[DB-Name]
When I switched it out to use a larger DB, using the Mongo URL of the form:
mongodb://[username]:[password]#db1-a1.example.net:27017,db2.example.net:2500/[DB-Name]?replicaSet=test
It throws a ‘ RangeError: Maximum call stack size exceeded’ error and won’t connect. This URL is the onlything that has changed between the databases.
I’ve checked the db details and can access it through RoboMongo / Robo 3T so the database definitely exists.
Trying to connect through Mongoose version ^5.2.10 using the following code:
function connect() {
if (MONGO_URL) {
mongoose.connect(MONGO_URL, err => {
if (err) {
console.log('error connecting')
console.log(err)
}
})
} else {
mongoose.connect(`mongodb://${host}`, {
user,
pass,
dbName,
useNewUrlParser: true //depresiation issue
}, err => {
if (err) {
console.log('error connecting')
console.log(err)
}
})
}
}
mongoose.connection.on('error', (message) => {
console.log('connection error!') //This is logged
console.log(message)
process.exit()
})
mongoose.connection.on('disconnected', connect)
connect()
Looks like you are trying to use a replica set. If so try to connect like following`
var uri = `mongodb://${userName}:${encodeURIComponent(password)}#${clusterName}/${dbName}?ssl=true&replicaSet=${process.env.replicaSetName}&authSource=${authDB}`
var db = mongoose.connect(uri).then().catch() // Whatever inside the then and catch blocks
`
Right now, I'm writing a small web application using node.js with my partner. In the application, we need to query some data from database using mongoose, then, send the data to the client.Trying to do this, I'm using the code below:
io.sockets.on('connection', function (socket) {
var id = socket.id;
socket.on('request', function (data) {
mongoose.createConnection(dbConfig.url);
var ClassX = require("./models/" + data.request);
var class_query = ClassX.findOne({}, function (err, result) {
if (err) {
console.log("There is an error: "+ err);
return handleError(err);
}
if (!result) {
console.log("No result!");
}
io.sockets.to(id).emit("response", result);
});
});
});
But it doesn't work.
And when the code is running, the log file of the database show some information like below:
2017-02-23T15:40:48.426+0800 I NETWORK [thread1] connection accepted from 127.0.0.1:5015 #3 (3 connections now open)
2017-02-23T15:40:48.428+0800 I NETWORK [conn3] received client metadata from 127.0.0.1:5015 conn3: { driver: { name: "n
odejs", version: "2.2.24" }, os: { type: "Windows_NT", name: "win32", architecture: "x64", version: "10.0.14393" }, plat
form: "Node.js v6.9.5, LE, mongodb-core: 2.1.8" }
The information "[conn3] received client metadata ..." seems weird. And, from the experience of many attempts, I think the callback function of ClassX.finOne() has not been executed. And I totally don't know why.
I build a blog. The blog uses NodeJS with mysql module to talk with database. As this is a basic CRUD application, I thought to break basic functionalities like read, update, etc into small modules and require them to a bigger one. The problem is that I haven't much experience with Node and it's asynchronous character, so I don't know if I implemented the callbacks from each module correctly. (I use the Error First Callback Pattern).
Take the bellow code as example. (The other modules are based on that structure as well)
module.exports = {
delete_author: function(author_email, callback) {
if (typeof(callback) === 'undefined') callback = function() {};
if (author_email != null || author_email != undefined) {
this.pool.getConnection(function(err, connection) {
if (err) callback(err);
connection.query(
'DELETE FROM authors WHERE author_email = ?', [author_email],
function(err, result) {
connection.release();
if (err) {
callback(err);
} else {
callback(null, result);
}
}
);
});
} else {
callback(new Error('No parameter provided to delete_author call.'));
}
}
}
The above module is a part of a bigger MYSQL module (the one I reffer to it above).
So in app.js I type:
var mysql = require('MYSQL');
// start a connection
mysql.delete_author('author_email#some.com', function(err, res) {
if (err) throw err;
// else do something here
}
Is my module structure okay? Am I defined and used the callback correctly? I want to point that this blog gets at least 20 visitors per day, and so far I haven't seen any strange behavior.
I always have multiple operations in one route or endpoint. Take an example below, when a user deletes an item, I want the related file be deleted in s3 too besides deleting related collection from the database.
So is the code below ok? Does it matter if I put the first function (delete file from s3) inside the DeleteItem function?
router.post('/item/delete', function(req, res) {
if(req.body.dlt_item){
var tempArray = [];
tempArray.push({"Key":req.body.dlt_item});
s3Bucket.deleteObjects({
Bucket: 'myS3',
Delete: {
Objects: req.body.dlt_item
}
}, function(err, data) {
if (err)
return console.log(err);
});
}
Item.DeleteItem(req.body.item_id, function(err,result){
if(err){console.log(err)}
res.send({result:1});
})
});
You should organise your code like this. This will ensure that s3 deletion will start only when mongodb deletion has finished.
In your code both things happen simultaneously. this may cause issue in some cases.
If one fails and other succeeds then there will be trouble. Suppose s3 files get deleted successfully and mongo deletion fails. Then you will have many references to non existing resources.
router.post('/item/delete', function(req, res) {
if(req.body.dlt_item){
var tempArray = [];
tempArray.push({"Key":req.body.dlt_item});
Item.DeleteItem(req.body.item_id, function(err,result){
if(err)
{
console.log(err)
res.send(err);
}
else
{
//deletion from mongodb is succesful now delete from s3
s3Bucket.deleteObjects({
Bucket: 'myS3',
Delete: {
Objects: req.body.dlt_item
}
},function(err, data) {
if (err)
{
// deletion from s3 failed you should handle this case
res.send({result:1});
return console.log(err);
}
else
{
// successful deletion from both s3 and mongo.
// If you do not want to wait for this then send the response before this function.
res.send({result:1});
}
});
}
})
});
so i have this problem i am working on 'following' feature in my application. What's important, i have two models:
Follows and Notifications
When I hit follow button in front-end I run function from follow.client.controller.js which POSTs to API endpoint /api/follows which corresponds to follow.server.controller.js and then update action on Follows model is performed - easy. AFAIK thats how it works (and it works for me).
But in follows.server.controller.js I want also invoke post to API endpoint at /api/notifications which corresponds to notifications.server.controller.js but I can't find a proper way to do that. Any help will be appreciated.
I don't want another call from front-end to add notification because it should be automatic = if user starts following someone, information is saved in both models at once.
You can add middleware in your server route.
app.route('/api/follows')
.post(notification.firstFunction, follows.secondFunction);
And now add 2 methods in your contollers. First makes the call to db and add's some result's data to request object which will be forwarded to second method.
exports.firstFunction= function(req, res, next) {
Notification.doSometing({
}).exec(function(err, result) {
if (err) return next(err);
req.yourValueToPassForward = result
next(); // <-- important
});
};
exports.secondFunction= function(req, res) {
//...
};
Or you can make few database calls in one api method, joining this calls with promises. Example:
var promise = Meetups.find({ tags: 'javascript' }).select('_id').exec();
promise.then(function (meetups) {
var ids = meetups.map(function (m) {
return m._id;
});
return People.find({ meetups: { $in: ids }).exec();
}).then(function (people) {
if (people.length < 10000) {
throw new Error('Too few people!!!');
} else {
throw new Error('Still need more people!!!');
}
}).then(null, function (err) {
assert.ok(err instanceof Error);
});