What is FirebaseCoreSDK

FirebaseCoreSDK is .net core library for interacting with firebase database, Cloud Messaging and storage. Library is supposed to be used in server side apps. This code is based on https://github.com/shoaibshakeel381/FirebaseCoreAdmin But it has improved code organization with additional fixes and enhancements. It supports

• Firebase Cloud Messaging (Tested Basic, Android and APNs Messaging modes, WebPush should work, but is untested)
• Firebase Realtime Database (Basic Crud, no Offline or Streaming support)
• Firebase Storage
• Authentication (Generate Custom Token, no user management)
• Logging (You can provide logger in FirebaseSDKConfiguration)
• Support for plugging custom HttpClient for supprting Mocks, IHttpClientFactory, Polly etc

Initialization

Supports both json and p12 config files. In order to give permissions to FirebaseCoreSdk to use your firebase project you need to first create private key in [service account] tab on (https://console.cloud.google.com/iam-admin/serviceaccounts). After creating service account you will be propmted to download either json file or p12 file, recommended is json file. Download that file and attach to your project.

• Json file

var configuration = new FirebaseSDKConfiguration {
    Credentials = new JsonServiceAccountCredentials("your-file.json")
};

var firebaseClient = new FirebaseClient(configuration);

• Json string

var configuration = new FirebaseSDKConfiguration {
    Credentials = new JsonServiceAccountCredentials("your-json-string", false)
};

var firebaseClient = new FirebaseClient(configuration);

• P12 file

var configuration = new FirebaseSDKConfiguration {
    Credentials = new P12ServiceAccountCredentials("your-file.p12", "your-secret", "your-service-account", "your-database")
};
var firebaseClient = new FirebaseClient(configuration);

Auth

Create token for some userId which should be used by client to authenticate against firebase database, that token could be used in client sdks by calling firebase.auth().signInWithCustomToken(token)

 var token = firebaseClient.Auth.CreateCustomToken(userId);

Developers will need to first get access token from google before actually calling any Firebase api. This can be done as follows:

await firebaseClient.Auth.AuthenticateAsync();

SDK will cache the access token in FirebaseSDKConfiguration object provided during initialization. SDK will then try to use it in every Firebase API call. Developers need to make sure that FirebaseSDKConfiguration object provided earlier is a singleton so they don't have to re-login every time a Firebase API needs to be called. If token is expired SDK will throw an Exception.

Database

Getting reference on some node of database use firebaseClient.Database.Ref("endpoint") for example firebaseClient.Database.Ref("users/12/details")

Query database

For getting data

• GetAsync
• GetWithKeyInjectedAsync

Examples: Let's say you have this structure in firebase -users/{userId}/events

                  --EventKey1
                  ---- CodeId: 1
                  ---- IsRead: true,
                  ---- Timestamp: 1502047422150
                  --EventKey2
                  ---- CodeId: 2
                  ---- IsRead: false,
                  ---- Timestamp: 1502047422279

Let's assume we have UserHistory class

class UserHistory {
    public int CodeId { get; set; }
    public bool IsRead { get; set; }
    public long Timestamp { get; set; }
}

and can query via

await firebaseClient.Auth.AuthenticateAsync();
var result = await firebaseClient.Database.Ref("users/330/events/EventKey2")
                .GetAsync<UserHistory>();

var queryBuilder = QueryBuilder.New()
                .Shallow(true)
                .StartAt("startvalu")
                .OrderBy("asd")
                .LimitToLast(1);

var result1 = await client.Database.Ref("users/330/events/EventKey2").GetAsync<T>(queryBuilder);

We can inject key into model by inheriting UserHistory: KeyEntity and instead of calling .GetAsync<UserHistory>() call .GetWithKeyInjectedAsync<UserHistory>() like:

await firebaseClient.Auth.AuthenticateAsync();
var result = await firebaseClient.Database.Ref("users/330/eventsEventKey2")
                .GetWithKeyInjectedAsync<UserHistory>();

Update database

• PushAsync
• SetAsync
• UpdateAsync
• DeleteAsync

Methods are functioning exactly like their counterparts in NodeJs or Java sdks.

Examples:

Push

await firebaseClient.Auth.AuthenticateAsync();
var result = await firebaseClient.Database.Ref("/users/30/details").PushAsync(new Detail())

Bulk update

await firebaseClient.Auth.AuthenticateAsync();
var result = await firebaseClient.Database.Ref("/users/30/details").UpdateAsync(new Dictionary<string, object>() {
                { "codeId", 20 } ,
                { "info","info"} ,
                { "sub/info","subinfo"} ,
             });

Set

await firebaseClient.Auth.AuthenticateAsync();
var result = await firebaseClient.Database.Ref("/test").SetAsync(new Test1());

Delete

await firebaseClient.Auth.AuthenticateAsync();
var result = await firebaseClient.Database.Ref("/test").DeleteAsync();

Storage

Following storage methods are supported

• GetPublicUrl
• GetSignedUrl
• RemoveObjectAsync
• GetObjectMetaDataAsync
• MoveObjectAsync

Examples:

await firebaseClient.Auth.AuthenticateAsync();
var result = await firebaseClient.Storage.GetObjectMetaDataAsync("test/my-image");

var publicUrl = firebaseClient.Storage.GetPublicUrl("my-image");

var signedUrl = firebaseClient.Storage.GetSignedUrl(new Firebase.Storage.SigningOption()
             {
                 Action = Firebase.Storage.SigningAction.Write,
                 Path = "my-image",
                 ContentType = "image/jpeg",
                 ExpireDate = DateTime.Now + new TimeSpan(0, 0, 0, 0, 60000000)
             });

Cloud Messaging

• SendCloudMessageAsync

Example:

await firebaseClient.Auth.AuthenticateAsync();

var message = new FirebasePushMessage();

var result = await firebaseClient.CloudMessaging.SendCloudMessageAsync(message);

Custom Http Request Handling

It is now possible to provide custom HTTP request handler by providing an implementation for IHttpClientProxy in FirebaseSDKConfiguration. SDK comes with a default implementation as TransientHttpClientProxy, clients can override it if need to. A sample implementation for using Polly is given below. In ASP.NET Core >= 2.1, it is recomended to also use IHttpRequestFactory to create instances of HttpClient.

Polly Sample Code:

public class FirebaseHttpClientProxy : TransientHttpClientProxy
{
    private readonly AsyncRetryPolicy<HttpResponseMessage> _retryPolicy;

    public FirebaseHttpClientProxy()
    {
        _retryPolicy = HttpPolicyExtensions
            .HandleTransientHttpError()
            .Or<FirebaseHttpException>(StatusCodeShouldBeRetried)
            .WaitAndRetryAsync(3, attempt => TimeSpan.FromSeconds(Math.Pow(2, attempt))));
    }

    /// <inheritdoc />
    public override async Task<string> SendAsync(Func<HttpRequestMessage> request)
    {
        var response = await _retryPolicy.ExecuteAsync(() => SendAsync(request()));
        return await GetResponseContent(response);
    }

    private async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request)
    {
        var uri = request.RequestUri;

        using (var client = new HttpClient()) // TODO: Use IHttpClientFactory here
        {
            var response = await client.SendAsync(request);
            await EnsureSuccessStatusCodeAsync(response, request, null).ConfigureAwait(false);
            
            return response;
        }
    }

    private static bool StatusCodeShouldBeRetried(FirebaseHttpException r)
    {
        if (r.ResponseMessage?.StatusCode < HttpStatusCode.InternalServerError)
        {
            return r.ResponseMessage.StatusCode == HttpStatusCode.RequestTimeout;
        }

        return true;
    }
}

Instance of this class can be provided in FirebaseSDKConfiguration which will be passed to FirebaseClient constructor.

var sdkConfiguration = new FirebaseSDKConfiguration 
    { 
        HttpClientProxy = new FirebaseHttpClientProxy(),
        Credentials = new JsonServiceAccountCredentials("json-service-account-credentials-string", false);
    };

var firebaseClient = new FirebaseClient(sdkConfiguration);