I am implementing a web application using Express and Docker. I am also using a Three layered architecture. When a user logs in, I store that information in a session. I have blogposts as a resource in my app. To retrieve the blogpostId I will send a query to the database in the Data access layer like this:
const db = require('./db')
exports.getBlogpostId = function(id ,callback){
const query = "SELECT * FROM blogposts WHERE blogId = ?"
const value = [id]
db.query(query, value, function(error, blogpost){
if(error){
callback("DatabaseError", null)
}else{
callback(null, blogpost)
}
})
}
Now in my Business logic layer I want to check if the user is logged in or not, something like this:
const blogRepo = require('../dal/blog-repository')
exports.getBlogpostId = function(id){
if(/*If the user is logged in*/){
return blogRepo.getBlogpostId(id)
}else{
throw "Unauthorized!"
}
}
How can I check if they are logged in here. How can I get the session that I stored when they logged in?
Thanks!
So, the business layer doesn't generically know anything about the logged in state at all. It's business logic, not web logic.
If you want it to have access to state like that, you have to pass that state into it as arguments any time you call it.
You can either decide that it's OK for the business logic to see the session object and pass the whole session object into it or you need to pass the specific pieces of the session object that the business logic needs such as the authentication state.
Related
Site is working with nodejs+socketio+mysql.
Is it normal to create a global object just before starting my app to store everything I have in the database? Something like user's password hashes for a very quick authentication process, compare the given token + userid.
var GS= {
users: {
user1: {
token: "Djaskdjaklsdjklasjd"
}
,
user555: {
token: "zxczxczxczxc"
}
,
user1239: {
token: "ertertertertertret"
}
}
};
On connect, node check user with gived user_id.
if (GS.hasOwnPropery("user"+user_id)) {
//compare gived token GS["user"+user_id].token
} else {
//go to database to get unknown id and then store it in GS
GS["user"+user_id] = { token: database_result };
}
And with everything else the same thing, using object property instead of querying the database. So if someone go to url /gameinfo/id/1, I just look in variable GS["game"+url_param] = GS["game"+1] = GS.game1
And of course, we don't talk about millions of rows in the database. 50-70k max.Don't really want to use something like Redis or Tarantool.
You can have a global object to store these info, but there are something to consider:
If you app are running by more than one machine (instance), this object won't be shared between these them.
This leads to some functional downsides, like:
you would need sticky session to make sure request from one particular client always directed to one particular instance
you can not check status of an user having data stored in another instance ...
Basically, anything that requires you to access user session data, will be hard, if not impossible, to do
In case your server goes down, all session data will be lost
Having a big, deep nested object is dangerously easy to mess up
If you are confident that you can handle these downsides, or you will not encounter them in your application, then go ahead. Otherwise, you should consider using a real cache library, framework.
It is my first time developing a SPA, and I am not using JS frameworks like React, Vue or Angular. My project just uses the firebase sdk and jquery to access the DOM elements.
In my app, the users can be associated with projects. Since that, I have a user-projects and project-users paths to represent that relationship.
When a user logs in my app I request users/uid to get the user data. After that I have to fetch the projects associated with the user. I will take the ids of the associated projects to finally request the data of each project.
I'm trying to use promises as described here, but I get nothing in the console.
function loadUserProjects() {
// Authenticated user
var user = firebase.auth().currentUser;
// General reference to the real time db
var ref = firebase.database().ref();
// Request the user data
ref.child('users/'+user.uid).on('value').then(function(snapshot) {
var user_data = snapshot.val(); console.log(user_data);
// Global variable to store the id of the selected project
project_selected_key = user_data.project_selected;
// Get the list of associated projects
return ref.child('user-projects/'+user.uid).on('value').then(function(snapshot) {
console.log(snapshot);
return snapshot;
});
}).then(function (projectsSnapshot) {
console.log(projectsSnapshot);
// List associated projects
var project_options = '';
projectsSnapshot.forEach(function (e) {
project_options += '<option value="'+e.key+'">'+e.val()+'</option>';
});
if (! project_options) {
project_options = '<option disabled selected value>- Ningún proyecto -</option>';
}
$('#project_selected').html(project_options);
}, function(error) {
// Something went wrong.
console.error(error);
});
}
I know that I have to use one additional request, because at this point the <select>will be populated with truevalues (the additional request have to query the full data of each project). But I am not getting messages in the console.
Thanks in advance.
After that, I need to define different levels of privilege in each project, and associate a level when a project is assigned to a specific user. Initially I was very excited about the real time, but it seems that firebase is getting more complicated than I supposed.
A Firebase on() listener can respond to multiple events. A promise can only resolve once, that's why it's only available when you use Firebase's once() operation.
return ref.child('user-projects/'+user.uid).once('value');
I have been trying for days to get a list of logged in users in a Meteor chat app.
I tried many different things. I managed to add a login flag on the user profile object.
Server side:
Accounts.onCreateUser(function(options, user) {
if(!options.profile){
options.profile = {}
}
options.profile.login = false;
if (options.profile)
user.profile = options.profile;
return user;
});
In the browser console I get this:
Meteor.user().profile
Object {login: false}
So that seems to work.
Now I want to list if users are logged in:
Client side
Deps.autorun(function(){
if(Meteor.userId()){
Meteor.user().profile.login=true;
}
});
After checking the login remains false when I log in.
This template html gives me a list of all usernames but not the login flag
{{#each allUsers}}
<p>{{username}}</p><p>{{profile.login}}</p>
{{/each}
So my problems are : profile.login remains false and I cannot display profile.login but the usernames are displayed.
Thank you in advance. Greetings Joris
To change the users profile.login property you need to do Meteor.users.update(..) or call a server method that does that. Just changing the user object's property will not work.
Generally I would recommend to not persist the users state into the mondodb database but hold it in a Collection in memory.
The easiest might be to just use one of these packages:
https://github.com/dburles/meteor-presence/
https://github.com/mizzao/meteor-user-status
or study their source code to see how to propagate the user status.
I have a FireBase db with a users store. I also use simple login email/pw. In the User store I save some extra info of a user - e.g. the lastlogin date. This is my workflow - from registering to logging in:
I register a user;
when registered it is added to the simple login email/pw sote;
I also add the registered user (includng the id returned from the simplelogin) in the users store. It is stored under a Firebase generated unique key.
I log in as that new user
When successful I get a user object from the simplelogin store:
email-"testuser1#test.com"
firebaseAuthToken-"eyJ0eXAiOiJKV1QiLCJhbGci...SoXkddR3A88vAkENCy5ilIk"
id-"46"
isTemporaryPassword-false
md5_hash-"6a4b6cb2045fd55f706eaebd6ab5d4f7"
provider-"password"
uid-"simplelogin:46"
Now I want to update the corresponding user in the User store - e.g. set the lastlogin key to now. But I only can update that user when I know the Firebase generated key it's under. How can I access that key?
The only other way to identify the user in the Users store is by retrieving all users in the Users store, looping through all of them and checking : does the current id key value match the id key value of the logged-in user. Looks a bit clumsy to me but I fear this is the only way I can do lookups with firebase?
When you save a registered user you should save them by their uid rather than a generated id. This way when the user logs back in we'll user the uid to get the user from the users node.
var fbRef = new Firebase('https://<YOUR-FIREBASE>.firebaseio.com');
var auth = new FirebaseSimpleLogin(fbRef, function(error, user) {
if (error) {
console.error(error);
} else if (user) {
// when a user logs in we can update their lastLogin here
// set the key to the uid for the user
// this would look like: https://myapp.firebaseio.com/users/1
fbRef.child('users').child(user.uid).update({
lastLogin: Firebase.ServerValue.TIMESTAMP // the time they logged in
});
}
});
// here when we create a user we will set the key to the uid under the users node
auth.createUser(email, password, function(error, user) {
// if there is no error
if (!error) {
// go to the users node, then set a location at the user's uid
// this would look like: https://myapp.firebaseio.com/users/1
fbRef.child('users').child(user.uid).set(user);
}
});
As the users are created our users node will look like this:
I am working on a messaging system using node.js + cradle and couchdb.
When a user pulls a list of their messages, I need to pull the online status of the user that sent them the message. The online status is stored in the user document for each registered user, and the message info is stored in a separate document.
Here is the only way I can manage to do what I need, but its hugely inefficient
privatemessages/all key = username of the message recipient
db.view('privatemessages/all', {"key":username}, function (err, res) {
res.forEach(function (rowA) {
db.view('users/all', {"key":rowA.username}, function (err, res) {
res.forEach(function (row) {
result.push({onlinestatus:row.onlinestatus, messagedata: rowA});
});
});
});
response.end(JSON.stringify(result));
});
Can someone tell me the correct way of doing this?
Thank you
Your code could return empty result because you are calling response at the time when user statuses may not yet be fetched from DB. Other problem is that if I received multiple messages from the same user, then call for his status may be duplicit. Below is a function which first fetch messages from DB avoiding duplicity of users and then get their statuses.
function getMessages(username, callback) {
// this would be "buffer" for senders of the messages
var users = {};
// variable for a number of total users I have - it would be used to determine
// the callback call because this function is doing async jobs
var usersCount = 0;
// helpers vars
var i = 0, user, item;
// get all the messages which recipient is "username"
db.view('privatemessages/all', {"key":username}, function (errA, resA) {
// for each of the message
resA.forEach(function (rowA) {
user = users[rowA.username];
// if user doesn't exists - add him to users list with current message
// else - add current message to existing user
if(!user) {
users[rowA.username] = {
// I guess this is the name of the sender
name: rowA.username,
// here will come his current status later
status: "",
// in this case I may only need content, so there is probably
// no need to insert whole message to array
messages: [rowA]
};
usersCount++;
} else {
user.messages.push(rowA);
}
});
// I should have all the senders with their messages
// and now I need to get their statuses
for(item in users) {
// assuming that user documents have keys based on their names
db.get(item, function(err, doc) {
i++;
// assign user status
users[item].status = doc.onlineStatus;
// when I finally fetched status of the last user, it's time to
// execute callback and rerutn my results
if(i === usersCount) {
callback(users);
}
});
}
});
}
...
getMessages(username, function(result) {
response.end(JSON.stringify(result));
});
Although CouchDB is a great document database you should be careful with frequent updates of existing documents because it creates entirely new document version after each update (this is because of it's MVCC model which is used to achieve high availability and data durability). Consequence of this behavior is higher disk space consumption (more data/updates, more disk space needed - example), so you should watch it and run database consumption accordingly.
I think your system could use an in memory hashmap like memcached. Each user status entry would expire after a time limit.
Mapping would be
[user -> lasttimeseen]
If the hashmap contains the user, then the user is online.
On some certain actions, refresh the lasttimeseen.
Then instead of pinging the whole world each time, just query the map itself and return the result.
I'm reminded of this presentation:
Databases Suck for Messaging
And its quote from Tim O'Reilly:
"On monday friendfeed polled flickr nearly 3 million times for 45000 users, only 6K of whom were logged in. Architectural mismatch."
As pointed out in the other answers, updates in CouchDB are expensive and should be avoided if possible, and there's probably no need for this data to be persistent. A cache or messaging system may solve your problem more elegantly and more efficiently.