GraphQL.DataLoader 5.3.0

GraphQL for .NET

This is an implementation of Facebook's GraphQL in .NET.

Now the specification is being developed by the GraphQL Foundation.

This project uses a lexer/parser originally written by Marek Magdziak and released with a MIT license. Thank you Marek!

Provides the following packages:

Package	Downloads	NuGet Latest
GraphQL
GraphQL.SystemTextJson
GraphQL.NewtonsoftJson
GraphQL.MemoryCache
GraphQL.DataLoader
GraphQL.MicrosoftDI

You can get all preview versions from GitHub Packages. Note that GitHub requires authentication to consume the feed. See here.

Documentation

1. http://graphql-dotnet.github.io - documentation site that is built from the docs folder in the master branch.
2. https://graphql.org/learn - learn about GraphQL, how it works, and how to use it.

Debugging

All packages generated from this repository come with embedded pdb and support Source Link. If you are having difficulty understanding how the code works or have encountered an error, then it is just enough to enable Source Link in your IDE settings. Then you can debug GraphQL.NET source code as if it were part of your project.

Installation

1. GraphQL.NET engine

This is the main package, the heart of the repository in which you can find all the necessary classes for GraphQL request processing.

> dotnet add package GraphQL

2. Serialization

For serialized results, you'll need an IGraphQLSerializer implementation. We provide several serializers (or you can bring your own).

> dotnet add package GraphQL.SystemTextJson
> dotnet add package GraphQL.NewtonsoftJson

Note: You can use GraphQL.NewtonsoftJson with .NET Core 3+, just be aware it lacks async writing capabilities so writing to an ASP.NET Core 3.0 HttpResponse.Body will require you to set AllowSynchronousIO to true as per this announcement; which isn't recommended.

3. Document Caching

For caching of parsed GraphQL documents you'll need an IDocumentCache implementation. We provide in-memory implementation on top of Microsoft.Extensions.Caching.Memory package.

> dotnet add package GraphQL.MemoryCache

For more information see Document Caching.

4. DataLoader

DataLoader is a generic utility to be used as part of your application's data fetching layer to provide a simplified and consistent API over various remote data sources such as databases or web services via batching and caching.

> dotnet add package GraphQL.DataLoader

For more information see DataLoader.

Note: Prior to version 4, the contents of this package was part of the main GraphQL.NET package.

5. Subscriptions

DocumentExecuter can handle subscriptions as well as queries and mutations. For more information see Subscriptions.

6. Advanced Dependency Injection

Also we provide some extra classes for advanced dependency injection usage on top of Microsoft.Extensions.DependencyInjection.Abstractions package.

> dotnet add package GraphQL.MicrosoftDI

For more information see Thread safety with scoped services.

Examples

https://github.com/graphql-dotnet/examples

You can also try an example of GraphQL demo server inside this repo - GraphQL.Harness. It supports the popular IDEs for managing GraphQL requests and exploring GraphQL schema:

• Altair
• Firecamp
• GraphiQL
• GraphQL Playground
• Voyager

Training

• API Development in .NET with GraphQL - Glenn Block demonstrates how to use the GraphQL.NET framework to build a fully functional GraphQL endpoint.
• Building GraphQL APIs with ASP.NET Core by Roland Guijt

Upgrade Guides

You can see the changes in public APIs using fuget.org.

• 4.x to 5.x
• 3.x to 4.x
• 2.4.x to 3.x
• 0.17.x to 2.x
• 0.11.0
• 0.8.0

Basic Usage

Define your schema with a top level query object then execute that query.

Fully-featured examples can be found here.

Hello World

using System;
using System.Threading.Tasks;
using GraphQL;
using GraphQL.Types;
using GraphQL.SystemTextJson; // First add PackageReference to GraphQL.SystemTextJson

var schema = Schema.For(@"
  type Query {
    hello: String
  }
");

var root = new { Hello = "Hello World!" };
var json = await schema.ExecuteAsync(_ =>
{
  _.Query = "{ hello }";
  _.Root = root;
});

Console.WriteLine(json);

Schema First Approach

This example uses the GraphQL schema language. See the documentation for more examples and information.

public class Droid
{
  public string Id { get; set; }
  public string Name { get; set; }
}

public class Query
{
  [GraphQLMetadata("droid")]
  public Droid GetDroid()
  {
    return new Droid { Id = "123", Name = "R2-D2" };
  }
}

var schema = Schema.For(@"
  type Droid {
    id: ID
    name: String
  }

  type Query {
    droid: Droid
  }
", _ => {
    _.Types.Include<Query>();
});

var json = await schema.ExecuteAsync(_ =>
{
  _.Query = "{ droid { id name } }";
});

Parameters

public class Droid
{
  public string Id { get; set; }
  public string Name { get; set; }
}

public class Query
{
  private List<Droid> _droids = new List<Droid>
  {
    new Droid { Id = "123", Name = "R2-D2" }
  };

  [GraphQLMetadata("droid")]
  public Droid GetDroid(string id)
  {
    return _droids.FirstOrDefault(x => x.Id == id);
  }
}

var schema = Schema.For(@"
  type Droid {
    id: ID
    name: String
  }

  type Query {
    droid(id: ID): Droid
  }
", _ => {
    _.Types.Include<Query>();
});

var json = await schema.ExecuteAsync(_ =>
{
  _.Query = $"{{ droid(id: \"123\") {{ id name }} }}";
});

Roadmap

Grammar / AST

• Grammar and AST for the GraphQL language should be compatible with the October 2021 specification.

Operation Execution

• Scalars
• Objects
• Lists of objects/interfaces
• Interfaces
• Unions
• Arguments
• Variables
• Fragments
• Directives
  • Include
  • Skip
  • Custom
• Enumerations
• Input Objects
• Mutations
• Subscriptions
• Async execution

Validation

• Arguments of correct type
• Default values of correct type
• Fields on correct type
• Fragments on composite types
• Known argument names
• Known directives
• Known fragment names
• Known type names
• Lone anonymous operations
• No fragment cycles
• No undefined variables
• No unused fragments
• No unused variables
• Overlapping fields can be merged
• Possible fragment spreads
• Provide non-null arguments
• Scalar leafs
• Unique argument names
• Unique directives per location
• Unique fragment names
• Unique input field names
• Unique operation names
• Unique variable names
• Variables are input types
• Variables in allowed position
• Single root field

Schema Introspection

GraphQL.NET supports introspection schema from October 2021 spec with some additional experimental introspection extensions.

Publishing NuGet packages

The package publishing process is automated with GitHub Actions.

After your PR is merged into master or develop, preview packages are published to GitHub Packages.

Stable versions of packages are published to NuGet when a release is created.

Contributors

This project exists thanks to all the people who contribute. <a href="https://github.com/graphql-dotnet/graphql-dotnet/graphs/contributors"><img src="https://opencollective.com/graphql-net/contributors.svg?width=890&button=false" /></a>

PRs are welcome! Looking for something to work on? The list of open issues is a great place to start. You can help the project simply respond to some of the asked questions.

The default branch is master. It is designed for non-breaking changes, that is to publish versions 5.x.x. If you have a PR with some breaking changes, then please target it to the develop branch that tracks changes for v6.0.0.

Backers

Thank you to all our backers! 🙏 Become a backer.

<a href="https://opencollective.com/graphql-net#backers" target="_blank"><img src="https://opencollective.com/graphql-net/backers.svg?width=890"></a>

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