Firebase.Xamarin

Light weight wrapper for Firebase Realtime Database REST API.

Installation

// Install release version
Install-Package Firebase.Xamarin

Supported frameworks

• .NET 4.5+
• ASP.Net Core 1.0
• Xamarin Android
• Xamarin iOS
• Xamarin iOS Classic
• Windows 8

Usage

Depending on your database rules you may need to first Authenticate with your Auth Provider. Instructions for Authentication are towards the bottom.

Querying

var firebase = new FirebaseClient("https://yourdatabase.firebaseio.com/");
var items = await firebase
  .Child("yourentity")
  //.WithAuth("<Authentication Token>") // <-- Add Auth token if required. Auth instructions further down in readme.
  .OrderByKey()
  .LimitToFirst(2)
  .OnceAsync<YourObject>();
  
foreach (var item in items)
{
  Console.WriteLine($"{item.Key} name is {item.Object.Name}");
}

Saving data

var firebase = new FirebaseClient("https://yourdatabase.firebaseio.com/");

// add new item to list of data 
var item = await firebase
  .Child("yourentity")
  //.WithAuth("<Authentication Token>") // <-- Add Auth token if required. Auth instructions further down in readme.
  .PostAsync(new YourObject());
  
// note that there is another overload for the PostAsync method which delegates the new key generation to the client
  
Console.WriteLine($"Key for the new item: {item.Key}");  

// add new item directly to the specified location (this will overwrite whatever data already exists at that location)
var item = await firebase
  .Child("yourentity")
  .Child("Ricardo")
  //.WithAuth("<Authentication Token>") // <-- Add Auth token if required. Auth instructions further down in readme.
  .PutAsync(new YourObject());

Realtime streaming

var firebase = new FirebaseClient("https://dinosaur-facts.firebaseio.com/");
var observable = firebase
  .Child("dinosaurs")
  .AsObservable<Dinosaur>()
  .Subscribe(d => Console.WriteLine(d.Key));
  

AsObservable<T> methods returns an IObservable<T> which you can take advantage of using Reactive Extensions

Authentication

firebase.google.com Auth

You will need a firebase.google.com API Key for Authentication. The easiset way to find this is to click on 'Add Firebase to your web app' in the Overview section of your firebase.google.com console. The site will generate a JavaScript snippet that contains the apiKey variable.

// Email/Password Auth
var authProvider = new FirebaseAuthProvider(new FirebaseConfig("<google.firebase.com API Key>"));

var auth = await authProvider.CreateUserWithEmailAndPasswordAsync("email@email.com", "password");

// The auth Object will contain auth.User and the Authentication Token from the request
System.Diagnostics.Debug.WriteLine(auth.FirebaseToken);


// Facebook Auth
var authProvider = new FirebaseAuthProvider(new FirebaseConfig("<google.firebase.com API Key>"));
var facebookAccessToken = "<login with facebook and get oauth access token>";

var auth = await authProvider.SignInWithOAuthAsync(FirebaseAuthType.Facebook, facebookAccessToken);

// Using the Auth token to make requests.. (see more on requests below)
var firebase = new FirebaseClient("https://dinosaur-facts.firebaseio.com/");
var dinos = await firebase
  .Child("dinosaurs")
  .WithAuth(auth.FirebaseToken) // <-- Note the use of the Firebase Auth Token
  .OnceAsync<Dinosaur>();

foreach (var dino in dinos)
{
  System.Diagnostics.Debug.WriteLine($"{dino.Key} is {dino.Object.Height}m high.");
}

Custom Auth

Generating Tokens

To generate tokens, you'll need your Firebase Secret which you can find by entering your Firebase URL into a browser and clicking the "Secrets" tab on the left-hand navigation menu.

Once you've downloaded the library and grabbed your Firebase Secret, you can generate a token with this snippet of .Net code:

var tokenGenerator = new Firebase.TokenGenerator("<YOUR_FIREBASE_SECRET>");
var authPayload = new Dictionary<string, object>()
{
  { "uid", "1" },
  { "some", "arbitrary" },
  { "data", "here" }
};
string token = tokenGenerator.CreateToken(authPayload);

The payload object passed into CreateToken() is then available for use within your security rules via the auth variable. This is how you pass trusted authentication details (e.g. the client's user ID) to your Firebase rules. The payload can contain any data of your choosing, however it must contain a "uid" key, which must be a string of less than 256 characters. The generated token must be less than 1024 characters in total.

Token Options

A second options argument can be passed to CreateToken() to modify how Firebase treats the token. Available options are:

• expires (DateTime) - A timestamp denoting the time after which this token should no longer be valid.

• notBefore (DateTime) - A timestamp denoting the time before which this token should be rejected by the server.

• admin (bool) - Set to true if you want to disable all security rules for this client. This will provide the client with read and write access to your entire Firebase.

• debug (bool) - Set to true to enable debug output from your security rules. You should generally not leave this set to true in production (as it slows down the rules implementation and gives your users visibility into your rules), but it can be helpful for debugging.

Here is an example of how to use the second options argument:

var tokenGenerator = new Firebase.TokenGenerator("<YOUR_FIREBASE_SECRET>");
var authPayload = new Dictionary<string, object>()
{
  { "uid", "1" },
  { "some", "arbitrary" },
  { "data", "here" }
};
string token = tokenGenerator.CreateToken(authPayload, new Firebase.TokenOptions(admin: true));
  

Thanks

Special thanks to bezysoftware for the original [firebase-database-dotnet] (https://github.com/step-up-labs/firebase-database-dotnet) and [firebase-authentication-dotnet] (https://github.com/step-up-labs/firebase-authentication-dotnet) code that is the core for this Xamarin adaptation. Also thanks to mikelehen for the original [Firebase Token Generator - .NET] (https://github.com/firebase/firebase-token-generator-dotNet)