Develop Reference

How to connect two users in firebase? [duplicate]

In my main page I have a list of users and i'd like to choose and open a channel to chat with one of them.
I am thinking if use the id is the best way and control an access of a channel like USERID1-USERID2.
But of course, user 2 can open the same channel too, so I'd like to find something more easy to control.
Please, if you want to help me, give me an example in javascript using a firebase url/array.
Thank you!

A common way to handle such 1:1 chat rooms is to generate the room URL based on the user ids. As you already mention, a problem with this is that either user can initiate the chat and in both cases they should end up in the same room.
You can solve this by ordering the user ids lexicographically in the compound key. For example with user names, instead of ids:
var user1 = "Frank"; // UID of user 1
var user2 = "Eusthace"; // UID of user 2
var roomName = 'chat_'+(user1<user2 ? user1+'_'+user2 : user2+'_'+user1);
console.log(user1+', '+user2+' => '+ roomName);
user1 = "Eusthace";
user2 = "Frank";
var roomName = 'chat_'+(user1<user2 ? user1+'_'+user2 : user2+'_'+user1);
console.log(user1+', '+user2+' => '+ roomName);
<script src="https://getfirebug.com/firebug-lite-debug.js"></script>
A common follow-up questions seems to be how to show a list of chat rooms for the current user. The above code does not address that. As is common in NoSQL databases, you need to augment your data model to allow this use-case. If you want to show a list of chat rooms for the current user, you should model your data to allow that. The easiest way to do this is to add a list of chat rooms for each user to the data model:
"userChatrooms" : {
"Frank" : {
"Eusthace_Frank": true
},
"Eusthace" : {
"Eusthace_Frank": true
}
}
If you're worried about the length of the keys, you can consider using a hash codes of the combined UIDs instead of the full UIDs.
This last JSON structure above then also helps to secure access to the room, as you can write your security rules to only allow users access for whom the room is listed under their userChatrooms node:
{
"rules": {
"chatrooms": {
"$chatroomid": {
".read": "
root.child('userChatrooms').child(auth.uid).child(chatroomid).exists()
"
}
}
}
}

In a typical database schema each Channel / ChatGroup has its own node with unique $key (created by Firebase). It shouldn't matter which user opened the channel first but once the node (& corresponding $key) is created, you can just use that as channel id.
Hashing / MD5 strategy of course is other way to do it but then you also have to store that "route" info as well as $key on the same node - which is duplication IMO (unless Im missing something).

We decided on hashing users uid's, which means you can look up any existing conversation,if you know the other persons uid.
Each conversation also stores a list of the uids for their security rules, so even if you can guess the hash, you are protected.

Hashing with js-sha256 module worked for me with directions of Frank van Puffelen and Eduard.
import SHA256 from 'crypto-js/sha256'
let agentId = 312
let userId = 567
let chatHash = SHA256('agent:' + agentId + '_user:' + userId)

Firebase rule resolving wrong

I'm trying to set firebase rules to my database but i'm having problem with data and newData
According to firebase:
newData A RuleDataSnapshot corresponding to the data that will result
if the write is allowed.
For .write and .validate rules, the newData variable gives you a
RuleDataSnapshot corresponding to the data that will result if the
write is allowed (it is a "merging" of the existing data plus the new
data being written).
So I have the following rule:
"users_details":{
"$uid":{
".write":"$uid == auth.uid && newData.exists()",
".read":"$uid == auth.uid",
".validate":"newData.child('auth').hasChild('crsfToken')",
}
User has a field auth which has a field crsfToken... so everytime someone writes a user i want to ensure the "edited" user will have auth/crsfToken
Ok.
Let's say a have an actual valid user abc.
Then i want to set another field on abc, that has no relation to any rule...
lets say: abc.field.subField = 1
so what I am doing is:
FirebaseDatabase.getInstance().getReference(Firebase.NODE_USERS_DETAILS).child(user.getUserid()).child("field").child("subField").setValue(1);
this isn't changing auth nor crsfToken but i'm getting Permision Denied
When I do a simulation on console, i see that isn't writing because the validate rule is denied
why? is there any way to debug firebase rules and see what is newData on a simulation?

Rules are resolving ok :) Because rules will be checked for all data manipulations on user_details/UID/*. So if you update user_detail/UID/field/subField, your rules will be checked and you will get access denied as you are. You said that you want to check for newData.auth.crsfToken and you are doing that indeed, but now you want to update field/subField without checking that? In which case you don't want to check crsfToken existence?

How to redirect two different users to different activity after login using firebase auth

I am creating an android application using the Firebase authentication and database.
For my app I need to identify the users after they logged in and redirect them to two different activities. (admin/simple user)
In my app I have only 10-20 users all time, and there isn't a way to register, it's a company only app.
Thanks for help.

If max users you expect is 20 then why would you need a authentication usage ( Google, Facebook ) etc. Have a simple database entry for all users as follows:
{
"app_title": "YourApp",
"users": {
"-KTYWvZG4Qn9ZYTc47O6": {
"username": "pkondedath",
"useremail": "hello#kondedath.com",
"password" : "hello123"
"userpic": "example.com/a.png",
"prevelidge" : "superuser"
},
"-KTYWvZG466ADFRR667": {
"username": "someone",
"useremail": "hello2#kondedath.com",
"password" : "hello1234"
"userpic": "example.com/b.png",
"prevelidge" : "normal"
}
}
}
Provide a user to input username( unique) and password and search through database to see if username and password matches and check his/her prevelidge and redirect to particular activity appropriately.
eg
mFirebaseRef = new Firebase("https://yourapp.firebaseio.com/").child("users")
Use above database reference to search users. You can also use the same to add new user. When adding a new user, give them default prevelidge.
This model fits well for less userbase like 20.
For more user bases( thousands, millions) you can use google authentication and use the User UID returned and create a new entry in your database(users).
Hope this helps you.

How to correctly nest data and write to Firebase

I have some Edittext that allows the user to enter data:
AppName
Date
Title
Quantity
User
I started a new Firebase project and it is currently a blank slate.
I am setting up my Firebase instance like this:
private DatabaseReference mDatabase;
mDatabase = FirebaseDatabase.getInstance().getReferenceFromUrl("https://myapp.firebase.io");
How I want it is everytime a new adding occurs, I would like to add it like this (AppName is the common ground for all entry):
AppName
Date
Title
Quantity
User
Date
Title
Quantity
User
...
...
AppName
Date
Title
Quantity
User
Date
Title
Quantity
User
...
...
How can I do the following:
The first time it is added, the AppName will be the parent node, and
anytime after Firebase should check to see if the parent node exist
and is the same and add it to that, otherwise create a new parent node
and add the children node to the new parent node.
I currently have my auth set up like this:
{
"rules": {
".read": "auth != null",
".write": "auth != null"
}
}
I had to change to true for my app to write to Firebase.
How can I:
Not register the user but only allow the app to able to write to
Firebase.
EDIT:
I am doing the following:
mDatabase.child("AppName").setValue(etName.getText().toString());
mDatabase.child("AppName").child("Date").setValue(etDate.getText().toString());
mDatabase.child("AppName").child("Title").setValue(etQuantity.getText().toString());
mDatabase.child("AppName").child("Quantity").setValue(User.getText().toString());
mDatabase.child("AppName").child("User").setValue(etUser.getText().toString());
Instead of adding, it is overwriting the previous entry. How can I append.

If I understood you, you need that not registered users could edit your database on Firebase and how to know If you added an ID.
First of all, as Ishan Fernando said, If you add data with the same id, this data will be overwrited, and using the push method, Firebase will create an unic ID to add you data
Read this: https://firebase.google.com/docs/database/android/read-and-write?hl=en
This Gist, thanks to the user realgt, could help you to know if the Appname exists or not: https://gist.github.com/anantn/4323949#gistcomment-998628
This will get all your data and you could check if you need add it or not
And, if you don't want to register users, but you need them to write the database, I think that you need to register them as anonymous users:
https://firebase.google.com/docs/auth/android/anonymous-auth
Firebase needs registered users (using social networks, email o anonymously) to modify it, so try the anonymous method. The problem is when the user get out of your app, this user will keep registered on your database. So, I recommend you, (Please, correct me if I'm wrong) to erase the user when onStop starts and create it again when onReady starts.
I hope it helps.

Can I make Firebase use a username login process?

I want to make a system which allows for username login. This process requires the following:
User must register with an email/password
The user can set a unique username
The user can sign in with either email or username
The user can recover their password via email or username
The functionality must work on a persistence enabled database
This question has been answered previously, but it disabled the functionality for the user to use password recovery. They also didn't address case-sensitivity, one person could register as "scooby" and another as "Scooby".

DISCLAIMER: This code is now over two years old. While this doesn't mean it's deprecated, I would strongly recommend investigating alternative methods before assuming this is the best approach. I personally wouldn't want the standard login process for Firebase to be dictated by my initial approach to a problem while Firebase wasn't as heavily adopted as it is now.
After multiple iterations of development I've come up with the following design to address this. I will post my code snippets in Swift, but they will typically be translatable directly into Android with ease.
Create a Firebase registration process for email/password.
This is required as the backbone of the user's sign-in experience. This can be implemented completely from the stock Firebase API documentation provided here
Prompt the user to enter their username
The username entry should be completed at registration, I'd recommend an additional field in the registration flow. I also recommend checking if the user has a username whenever they log in. If they don't, then display a SetUsername interface that prompts them to set a username before progressing further into the UI. A user might not have a username for a few reasons; it could be revoked for being rude or reserved, or they might have signed up prior to the username being required at registration.
Make sure that if you're using a persistence-enabled Firebase build that you use Firebase Transactions. The transactions are necessary, otherwise your app can make assumptions about the data in the username table, even though a username might have been set for a user only seconds earlier.
I would also advise enforcing the username to be nearly alphanumeric (I allow for some harmless punctuation). In Swift I can achieve this with the following code:
static var invalidCharacters:NSCharacterSet {
let chars = NSMutableCharacterSet.alphanumericCharacterSet()
// I add _ - and . to the valid characters.
chars.addCharactersInString("_-.")
return chars.invertedSet
}
if username.rangeOfCharacterFromSet(invalidCharacters) != nil {
// The username is valid
}
Saving the user data
The next important step is knowing how to save the user's data in a way that we can access it in the future. Below is a screenshot of the way I store my user data:
A few things to note:
The usernames are stored twice, once in usernames and again in details/[uid]/username. I recommend this as it allows you to be case sensitive with usernames (see the next point) and it also allows you to know the exact database reference to check a username (usernames/scooby) rather than having to query or check through the children of details to find a username that matches (which would only become more complicated when you have to factor in case-sensitivity)
the usernames reference is stored in lowercase. When I check the values in this reference, or when I save to this reference, I ensure that I only save data in lowercase. This means if anyone wants to check if the username 'scoobY' exists, it will fail because in lowercase it's the same username as the existing user "Scooby".
The details/[uid]/username field contains capitals. This allows for the username to display in the case of preference for the user, rather than enforcing a lowercase or Capitalised word, the user can specify their name as "NASA Fan" and not be converted over to "Nasa Fan", while also preventing anyone else from registering the username "NASA FAN" (or any other case iterations)
The emails are being stored in the user details. This might seem peculiar because you can retrieve the current user's email via Firebase.auth().currentUser.email?. The reason this is necessary is because we need references to the emails prior to logging in as the user.
Logging in with email or username
For this to work seamlessly, you need to incorporate a few checks at login.
Since I've disallowed the # character in usernames, I can assume that a login request containing an # is an email request. These requests get processed as normal, using Firebase's FIRAuth.auth().signInWithEmail(email, password, completion) method.
For all other requests, we will assume it's a username request. Note: The cast to lowercase.
let ref = FIRDatabase.database().reference()
let usernameRef = ref.child("users/usernames/\(username.lowercaseString)")
When you perform this retrieval, you should consider if you have persistence-enabled, and if there's a possibility that a username could be revoked. If a username could be revoked and you have persistence-enabled, you will want to ensure you retrieve the username value within a Transaction block, to make sure you don't get a cached value back.
When this retrieval succeeds, you get the value from username[username], which is the user's uid. With this value, you can now perform a retrieval on the user's email value:
let ref = FIRDatabase.database().reference()
let usernameRef = ref.child("users/details/[uid]/email")
Once this request succeeds, you can then perform the standard Firebase email login with the email string you just retrieved.
The exact same retrieval methods can be used to retrieve an email from a username to allow for password recovery.
A few points to be wary of for advanced functionality:
- If you allow the user to update their email using FIRUserProfileChangeRequest, make sure you update it both on the auth AND the details[uid]email field, otherwise you will break the username login functionality
- You can significantly reduce the code required to handle all the different failure cases in the retrieval methods by using success and failure blocks. Here's an example of my get email method:
static func getEmail(username:String, success:(email:String) -> Void, failure:(error:String!) -> Void) {
let usernameRef = FIRDatabase.database().reference().child("users/usernames/\(username.lowercaseString)")
usernameRef.observeSingleEventOfType(.Value, withBlock: { (snapshot) in
if let userId = snapshot.value as? String {
let emailRef = FIRDatabase.database().reference().child("users/details/\(userId)/email")
emailRef.observeSingleEventOfType(.Value, withBlock: { (snapshot) in
if let email = snapshot.value as? String {
success(email: email)
} else {
failure(error: "No email found for username '\(username)'.")
}
}) { (error) in
failure(error: "Email could not be found.")
}
} else {
failure(error: "No account found with username '\(username)'.")
}
}) { (error) in
failure(error: "Username could not be found.")
}
}
This success/failure block implementation allows the code I call in my ViewControllers to be much cleaner. Å login calls the following method:
if fieldText.containsString("#") {
loginWithEmail(fieldText)
} else {
// Attempt to get email for username.
LoginHelper.getEmail(fieldText, success: { (email) in
self.loginWithEmail(email)
}, failure: { error in
HUD.flash(.Error, delay: 0.5)
})
}