I'm creating my first web application using Hapi, MongoDb, NodeJS & Angular. I can already get and save some data from my app.
Now each time I need to refresh the data in the browser, I must restart the server. Because data is only fetched on server start, using the following function:
var getUsers = function(db, callback) {
db.collection("users", function(err, collection) {
if (err) return callback(err, "error getting collection");
collection.find({}).toArray(function(err, users) {
if (err) return callback(err, "error getting find()");
console.log("returning users list: ");
Common.setUsers(users);
//console.log(Common.getUsers());
});
});
};
The users can then be fetched via Common.getUsers()
Now what if I want to create a list that shows me - in realtime - which users register for my application? So without a need for server restart. How can I achieve this?
I've done a bit of searching and found RethinkDb, which has changefeeds. (I wish I found this earlier). MongoDb doesn't have changefeeds the way Rethink implements it.
Is there a way that I can create these changefeeds myself? Or is there another tool that can achieve this for me which works with MongoDb?
A little late but I created a playground application which shows how to build a realtime timeline with hapi and the nes plugin. It also utilizes RethinkDB and makes use of their changefeed feature:
Realtime timeline with hapi.js, nes and RethinkDB
Maybe this also helps you a little bit.
Related
I have created and an API endpoint with Firebase Functions usign node.js. This
API endpoint collect JSON data from client browser and I am saving that JSON data to Firebase Firestore databse using Firebase Functions.
While this works fine but when I see Firestore usage tab it's shows really high number of read operations even I have not created any read function till now.
My API is in Production and and current usage data is : Reads 9.7K, Writes 1K, Deletes 0.
I have already tried to check with Firebase Firestore Document and Pricing but never seems to find anything on this issue.
I am using Firestore add function to create document with an auto generated document id. ValidateSubscriberData() is a simple function to validate client req.body inputs which is JSON data.
app.post('/subscribe', (req, res) => {
let subscriber = {};
ValidateSubscriberData(req.body)
.then(data => {
subscriber = data;
//console.log(data);
subscriber.time = Date.now();
return subscriber;
})
.then(subscriber => {
//console.log(subscriber);
// noinspection JSCheckFunctionSignatures
return db.collection(subscriber.host).add(subscriber);
})
.then(document => {
console.log(document.id);
res.json({id: document.id, iid: subscriber.iid});
return 0;
})
.catch(error => {
console.log({SelfError: error});
res.json(error);
});
});
I don't know this is an issue with Firestore or I am doing something in a way that makes read operations internally but I want find a way so I can optimize my code.
English is not my first language and I am trying my best explain my issue.
I think Firestore is working perfectly fine and my code too. I assume Firebase is counting those reads which I made through Firebase Console.
To verify this I have clicked on Data tab on Firestore page and scroll down to make all document name/id visible. And after that I see 1K Reads added on my old stats. So its proven Firestore counting all reads even its from firebase console and it is obvious but my bad I have not thinking about this before.
I don't think this question has any relevance but may be people like me find it helpful before posting any silly question on this helpful platform.
I'm trying to decide between two methods for inserting a new document to a collection from the client using Meteor.js. Call a Server Method or using the db API directly.
So, I can either access the db api directly on the client:
MyCollection.insert(doc)
Or, I can create a new Server Method (under the /server dir):
Meteor.methods({
createNew: function(doc) {
check(doc, etc)
var id = MyCollection.insert(doc);
return project_id;
}
});
And then call it from the client like this:
Meteor.call('createNew', doc, function(error, result){
// Carry on
});
Both work but as far as I can see from testing, I only benefit from latency compensation (the local cache updating and showing on the screen before the server responds) if I hit the db api directly, not if I use a Server Method, so my preference is for doing things this way. But I also get the impression the most secure approach is to use a Method on the server (mainly because Emily Stark gave it as an example in her video here) but then the db api is available on the client no matter what so why would a Server Method be better?
I've seen both approaches taken when reading source code elsewhere so I'm stumped.
Note. In both cases I have suitable Allow/Deny rules in place:
MyCollection.allow({
insert: function(userId, project){
return isAllowedTo.createDoc(userId, doc);
},
update: function(userId, doc){
return isAllowedTo.editDoc(userId, doc);
},
remove: function(userId, doc){
return isAllowedTo.removeDoc(userId, doc);
}
});
In short: Which is recommended and why?
The problem was that I had the method declarations under the /server folder, so they were not available to the client and this broke latency compensation (where the client creates stubs of these methods to simulate the action but in my case could not because it couldn't see them). After moving them out of this folder I am able to use Server Methods in a clean, safe and latency-compensated manner (even with all my Allow/Deny rules set to false - they do nothing and only apply to direct db api access from the client, not server).
In short: don't use the db api on the client or allow/deny rules on the server, forget they ever existed and just write Server Methods, make sure they're accessible to both client and server, and use these for crud instead.
I read :
How do I manage MongoDB connections in a Node.js web application?
http://mongodb.github.io/node-mongodb-native/driver-articles/mongoclient.html
How can I set up MongoDB on a Node.js server using node-mongodb-native in an EC2 environment?
And I am really confused. How I should work with mongoDB from node.js? I’m a rookie, and my question may look stupid.
var db = new db.MongoClient(new db.Server('localhost', 27017));
db.open(function(err, dataBase) {
//all code here?
dataBase.close();
});
Or every time when I needing something from db I need call:
MongoClient.connect("mongodb://localhost:27017/myDB", function(err, dataBase) {
//all code here
dataBase.close();
});
What is the difference betwen open and connect? I read in the manual that open: Initialize and second connect. But what exactly does that mean? I assume that both do the same, but in the other way, so when should I use one instead the other?
I also wanna ask it's normal that mongoClient needing 4 socket? I running two myWEbServer at the same time, here’s picture:
http://i43.tinypic.com/29mlr14.png
EDIT:
I wanna mention that this isn't a problem ( rather doubt :D), my server works perfect. I ask because I wanna know if I am using mongoDB driver correctly.
Now/Actually I use first option,init mongo dirver at the beginning and inside load put all code.
I'd recommend trying the MongoDB tutorial they offer. I was in the same boat, but this breaks it down nicely. In addition, there's this article on github that explains the basics of DB connection.
In short, it does look like you're doing it right.
MongoClient.connect("mongodb://localhost:27017/myDB", function(err, dataBase) {
//all code here
var collection = dataBase.collection('users');
var document1 = {'name':'John Doe'};
collection.insert(document1, {w:1}, function(err,result){
console.log(err);
});
dataBase.close();
});
You still can sign up for a free course M101JS: MongoDB for Node.js Developers, provided by MongoDB guys
Here is short description:
This course will go over basic installation, JSON, schema design,
querying, insertion of data, indexing and working with language
drivers. In the course, you will build a blogging platform, backed by
MongoDB. Our code examples will be in Node.js.
I had same question. I couldn't find any proper answer from mongo documentation.
All document say is to prefer new db connection and then use open (rather than using connect() )
http://docs.mongodb.org/manual/reference/method/connect/
So I have been playing with NodeJS/Express for a little with now and I would really like to try to rewrite a relatively large side project using a full JavaScript stack just to see how it will work. Sails.js seems to be a pretty good choice for a NodeJS backend for a REST API with support for web sockets which is exactly what I am looking for however is one more issue I am looking to resolve and that is transactional SQL within NodeJS.
Most data layer/orms I have seen on the NodeJS side of things don't seem to support transactions when dealing with MySQL. The ORM provided with Sails.js (Waterline) also does not seem to support transactions which is weird because I have seen places where is mentioned it did though those comments are quite old. Knex.js has support for transactions so I was wondering if it is easy to replace the ORM is Sails.js with this (or if Sails.js assumes Waterline in the core framework).
I was also wondering if there is an ORM built on top of Knex.js besides Bookshelf as I am not a fan of Backbones Model/Collection system?
You can still write SQL queries directly using Model.query(). Since this is an asynchronous function, you'll have to use promises or async to reserialize it. For instance, using the MySQL adapter, async, and a model called User:
async.auto({
transaction: function(next){
User.query('BEGIN', next);
},
user: ['transaction', function(next) {
User.findOne(req.param('id')).exec(next);
}],
// other queries in the transaction
// ...
}, function(err, results) {
if (err) {
User.query('ROLLBACK', next);
return next(err);
}
User.query('COMMIT', next);
// final tasks
res.json(results.serialize);
});
We're working on native support for transactions at the ORM level:
https://github.com/balderdashy/waterline/issues/62
Associations will likely come first, but transactions are next. We just finished GROUP BY and aggregations (SUM, AVG, etc.)
Transactions in SailsJS turned out to be much trickier than anticipated. The goal is to let the ORM adapter know that two very disparate controller actions on models are to be sent through a single MySQL connection.
The natural way to do it is two write a new adapter that accepts an additional info to indicate that a query belongs to a transaction call. Doing that requires a change in waterline (sails ORM abstraction module) itself.
Checkout if this helps - https://www.npmjs.com/package/sails-mysql-transactions
First of all, i am very much a newbie to all the technologies mentioned in this post.
I am working on something, where I have sensors, which would send their reading via HTTP post. The sensor would send the sensed value periodically over http as XML.
I found a link here that explains how to create REST API.
Now in the link above it is quite clear untill the point, the author installs mongoDB. But after that point things get complex and the author didn't give an explanation what is happening in the code after.
What I am not able to figure out is,
How to create a database in node.js using mondgoDB and expose this database over http, for the sensors to send the readings.
How can I access this database in my URI's?
How can I access the date and time the data was added onto database.
I would really appreciate any help.
I am no node.js expert but the same rules apply across the board for this kind of stuff.
You must understand that your database will not be accessible directly. Instead it will be accesses from node.js. You can add a --rest option to MongoDBs startup which will start a self contained RESTlet within the mongod program, but this is probably not an awesome idea here.
As far as I can see your jkust confused about the layers, which is common in this scenario, so to explain:
Your sensors will POST data (I would probably change that to JSON format, it is more expressive and smaller than XML) out to your node.js server running on, i.e. 81.187.205.13
It will post to whatever destination your rest function to deal with this data is running, i.e. /someawesomecontroller/notsuchagoodfunction
That function (as described by the tutorial you linked) will then pick up this POST, parse it and use the default method within node.js (via the driver) to insert into MongoDB. You can see the guy who wrote that tutorial doing that in the later partsd, i.e.:
exports.findById = function(req, res) {
var id = req.params.id;
console.log('Retrieving wine: ' + id);
db.collection('wines', function(err, collection) {
collection.findOne({'_id':new BSON.ObjectID(id)}, function(err, item) {
res.send(item);
});
});
};
So really now all you need are some tutorials on how the MongoDB driver in node.js works, here is a nice starting place: Do you know any tutorial for mongoDB in nodeJS?
Hope it helps,