GraphQL for .NET - Subscription Transport WebSockets

Provides the following packages:

Package	Downloads	Nuget Latest	MyGet Latest
GraphQL.Server.Core
GraphQL.Server.Transports.AspNetCore
GraphQL.Server.Transports.AspNetCore.NewtonsoftJson
GraphQL.Server.Transports.AspNetCore.SystemTextJson
GraphQL.Server.Transports.Subscriptions.Abstractions
GraphQL.Server.Transports.WebSockets
GraphQL.Server.Ui.Altair
GraphQL.Server.Ui.Playground
GraphQL.Server.Ui.GraphiQL
GraphQL.Server.Ui.Voyager
GraphQL.Server.Authorization.AspNetCore

Transport compatible with Apollo subscription protocol.

Getting started

For just the HTTP middleware:

dotnet add package GraphQL.Server.Transports.AspNetCore

The HTTP middleware needs an IGraphQLRequestDeserializer implementation:

.NET Core 3+:
dotnet add package GraphQL.Server.Transports.AspNetCore.SystemTextJson
Legacy (prior to .NET Core 3):
dotnet add package GraphQL.Server.Transports.AspNetCore.NewtonsoftJson
(or your own)

For more information on how to migrate from Newtonsoft.Json to System.Text.Json see this article.

For the WebSocket subscription protocol (depends on above) middleware:

dotnet add package GraphQL.Server.Transports.WebSockets

For the UI middleware/s:

dotnet add package GraphQL.Server.Ui.Altair
dotnet add package GraphQL.Server.Ui.GraphiQL
dotnet add package GraphQL.Server.Ui.Playground
dotnet add package GraphQL.Server.Ui.Voyager

You can get the latest pre-release packages from the MyGet feed, where you may want to explicitly pull a certain version using -v.

> dotnet add package GraphQL.Server.Transports.AspNetCore -v 3.5.0-alpha0046

Configure

See the sample project's Startup.cs for full details.

public void ConfigureServices(IServiceCollection services)
{
    // Add GraphQL services and configure options
    services
        .AddSingleton<IChat, Chat>()
        .AddSingleton<ChatSchema>()
        .AddGraphQL(options =>
        {
            options.EnableMetrics = Environment.IsDevelopment();
            options.ExposeExceptions = Environment.IsDevelopment();
            options.UnhandledExceptionDelegate = ctx => { Console.WriteLine(ctx.OriginalException) };
        })
        // Add required services for de/serialization
        .AddSystemTextJson(deserializerSettings => { }, serializerSettings => { }) // For .NET Core 3+
        .AddNewtonsoftJson(deserializerSettings => { }, serializerSettings => { }) // For everything else
        .AddWebSockets() // Add required services for web socket support
        .AddDataLoader() // Add required services for DataLoader support
        .AddGraphTypes(typeof(ChatSchema)) // Add all IGraphType implementors in assembly which ChatSchema exists 
}

public void Configure(IApplicationBuilder app)
{
    // this is required for websockets support
    app.UseWebSockets();

    // use websocket middleware for ChatSchema at path /graphql
    app.UseGraphQLWebSockets<ChatSchema>("/graphql");

    // use HTTP middleware for ChatSchema at path /graphql
    app.UseGraphQL<ChatSchema>("/graphql");

    // use graphiQL middleware at default url /ui/graphiql
    app.UseGraphiQLServer(new GraphiQLOptions());

    // use graphql-playground middleware at default url /ui/playground
    app.UseGraphQLPlayground(new GraphQLPlaygroundOptions());

    // use altair middleware at default url /ui/altair
    app.UseGraphQLAltair(new GraphQLAltairOptions());
    
    // use voyager middleware at default url /ui/voyager
    app.UseGraphQLVoyager(new GraphQLVoyagerOptions());
}

UserContext and resolvers

UserContext of your resolver will be type of MessageHandlingContext. You can access the properties including your actual UserContext by using the Get<YourContextType>("UserContext") method. This will read the context from the properties of MessageHandlingContext. You can add any other properties as to the context in IOperationMessageListeners. See the sample for example of injecting ClaimsPrincipal.

Sample

Samples.Server shows a simple Chat example demonstrating the subscription transport. It can be run as netcoreapp2.2, netcoreapp3.0 or netcoreapp3.1, and supports various GraphQL client IDEs (by default opening GraphQL Playground).

Here are some example queries to get started. Use three browser tabs or better yet windows to view the changes.

Subscription 1

Query:

subscription MessageAddedByUser($id:String!) {
  messageAddedByUser(id: $id) {
    from { id displayName }
    content
  }
}

Variables:

{
  "id": "1"
}

Subscription 2

subscription MessageAdded {
  messageAdded {
    from { id displayName }
    content
  }
}

Mutation