A crucial component of contemporary asynchronous programming is GraphQL for.NET – Cancellation Token, especially when it comes to GraphQL APIs created with.NET technologies. The responsiveness and effectiveness of your GraphQL services can be greatly improved by knowing how to use CancellationToken.

This guide examines the complex way that CancellationToken is implemented in GraphQL apps that are constructed using the .NET framework. Developers can guarantee more seamless handling of asynchronous processes, providing more control over task cancellation and resource management, by becoming proficient with CancellationToken integration.

Stay with us as we explore the nuances of GraphQL for.NET – Cancellation Token, giving you the tools you need to improve your development processes and get the most out of your GraphQL APIs.

First, let’s ensure you have the .NET SDK installed. Open your terminal or command prompt and run:

1. Create a New .NET Project

Code Syntax : dotnet new webapi -n GraphQLCancellationTokenExample
cd GraphQLCancellationTokenExample

2. Add the GraphQL Dependencies

Code Syntax : dotnet add package GraphQL
dotnet add package GraphQL.Server.Transports.AspNetCore

3. Example Code

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using GraphQL;
using GraphQL.Types;
using GraphQL.Server;
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton<ISchema, ExampleSchema>(services => new ExampleSchema(new SelfActivatingServiceProvider(services)));
builder.Services.AddGraphQL(options =>
{
options.EnableMetrics = false;
}).AddSystemTextJson();
var app = builder.Build();
if (app.Environment.IsDevelopment())
{ app.UseDeveloperExceptionPage();
}
app.UseGraphQL<ISchema>();
app.UseGraphQLPlayground(); // To test your queries
app.Run();
public class ExampleQuery : ObjectGraphType
{ public ExampleQuery() { Field<StringGraphType>( "hello", arguments: new QueryArguments(new QueryArgument<IntGraphType> { Name = "delay" }), resolve: context => { var delay = context.GetArgument<int>("delay", 0); var cancellationToken = context.CancellationToken; return Task.Run(async () => { await Task.Delay(delay, cancellationToken); return "Hello, world!"; }, cancellationToken); } ); }
}
public class ExampleSchema : Schema
{ public ExampleSchema(IServiceProvider provider) : base(provider) { Query = provider.GetRequiredService<ExampleQuery>(); }
}

Explanation

  1. Setting Up the Project:
    • We start by creating a new web API project and adding the necessary GraphQL packages.
  2. Dependency Injection and Service Registration:
    • The Program.cs file sets up the necessary services for GraphQL, including adding a singleton ISchema and configuring GraphQL options.
  3. Defining the Query:
    • ExampleQuery class inherits from ObjectGraphType and defines a single field hello. This field takes an optional delay argument (of type IntGraphType) and uses the resolve function to implement the logic.
    • Inside the resolve function, we use context.CancellationToken to get the cancellation token passed from the request.
  4. Using the Cancellation Token:
    • We run an asynchronous task with a delay specified by the delay argument. The task uses the cancellation token to support cancellation.
    • If the cancellation token is triggered (e.g., the client cancels the request), the task will be cancel, and the operation will not complete.
  5. Running the Application:
    • The application is configure to use GraphQL and GraphQL Playground, which allows testing the queries.

4. Testing the Cancellation Token

A. Run the Application:

Code Syntax : dotnet run

B . Open GraphQL Playground (usually at http://localhost:5000/ui/playground).

C. Execute the following query to test the delay and cancellation:

Code Syntax : query($delay: Int) { hello(delay: $delay) }

D. To test cancellation, you can cancel the request manually in the Playground before it completes.

Conclusion

In summary, learning GraphQL for.NET’s CancellationToken is essential for maximizing the effectiveness and responsiveness of your APIs. Developers may guarantee more efficient asynchronous activities and better resource management, which will increase the performance of their applications overall, by skillfully incorporating CancellationToken.

Are you looking to use GraphQL for.NET and require professional advice? Hire .Net Core developers who specialize in asynchronous programming and GraphQL. Their knowledge can help you design scalable, reliable GraphQL APIs that satisfy the needs of contemporary applications while also streamlining your development process.