Tanka GraphQL .NET Client library

This library provides easy to use cross-platform client API for Tanka GraphQL execution library based server using ASP.NET Core SignalR .NET Clients HubConnection.

Features

Execute queries, mutations and subscriptions using SignalR HubConnection
Supports GraphQL validation and tracing
Leverage power of SignalR communication techniques (WebSockets, Server-Sent Events, Long Polling)

Gettings started

Install

Current release is available on Nuget gallery.

Install-Package Tanka.GraphQL.Net.Client -Version 0.3.2

To access latest (pre-release) builds, you can connect to a following feed:

https://pkgs.dev.azure.com/anttikajanus/_packaging/tanka-graphql-net-client-packages/nuget/v3/index.json

See how to add custom nuget feeds in Visual Studio from here

Short API summary

Add usings

using Tanka.GraphQL;

Defining models

You can define your DTOs as POCOs. In these examples, I'm using separate models for input and output messages.

public class Message
{
    public int Id { get; set; }
    public string Content { get; set; }
}

public class InputMessage
{
    public string Content { get; set; }
}

Connect to the server endpoint

Create SignalR HubConnection normally. Read more how to connect to a hub

Read more about the server implementation from Tanka GraphQL documentation

var connection = new HubConnectionBuilder()
                    .WithUrl("http://localhost:5000/hubs/graphql")
                    .Build();
await connection.StartAsync();

Queries and mutations

In GraphQL both queries and mutations are defined as queries so they are handled the same way in the API.

Query

var channelId = 1;

var channelMessageGQL = @"query Messages($channelId: Int!) {
                messages(channelId: $channelId) {
                  id
                  content
                }
            }";

var queryRequest = new QueryRequest()
{
    Query = channelMessageGQL,
    Variables = new Dictionary<string, object>()
        {
            { "channelId", channelId }
        }
};

var result = await connection.QueryAsync(queryRequest);
var data = result.GetDataFieldAs<List<Message>>();

Mutation

var postMessageMutationGQL = @"mutation PostMessage($channelId: Int!, $message: InputMessage) {
               postMessage(channelId: $channelId, message: $message) {
                 id
                 content
               }
            }";

var queryRequest = new QueryRequest()
{
    Query = postMessageMutationGQL,
    Variables = new Dictionary<string, object>()
        {
            { "channelId", channelId },
            { "message", new InputMessage() { Content = message } }
        }
};

var result = await connection.QueryAsync(queryRequest);
var data = result.GetDataFieldAs<Messages>();

Subscription

API provides support for subscriptions as streams using IObservable<ExecutionResult>. You can subscribe to the stream using Subscribe method.

 var channelSubsribtionGQL = @"subscription MessageAdded($channelId: Int!) {
                messageAdded(channelId: $channelId) {
                  id
                  content
                }
            }";

var queryRequest = new QueryRequest()
{
    Query = channelSubsribtionGQL,
    Variables = new Dictionary<string, object>()
        {
            { "channelId", channelId}
        }
};

var subscriptionSource = new CancellationTokenSource();
var serverSubscription = await connection.SubscribeAsync(request, subscriptionSource);
serverSubscription.Subscribe(
                // On new message added
                result =>
                {
                    var message = result.GetDataFieldAs<Message>();
                    // Handle new message added
                },
                // On error corrured
                error =>
                {
                    //Handle error
                },
                // On completed
                () =>
                {
                   //No more messages coming
                });
                
// Cancelling the subscription                
subscriptionSource.Cancel();

anttikajanus / tanka-graphql-net-client