GraphQL for .NET

This is a work-in-progress implementation of Facebook's GraphQL in .NET.

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

Installation

You can install the latest version via NuGet.

PM> Install-Package GraphQL

Upgrade Guide

• 0.11.0
• 0.8.0

GraphiQL

There is a sample web api project hosting the GraphiQL interface. npm install and build webpack from the root of the repository.

> npm install
> npm start

Usage

Define your type system with a top level query object.

public class StarWarsSchema : Schema
{
  public StarWarsSchema()
  {
    Query = new StarWarsQuery();
  }
}

public class StarWarsQuery : ObjectGraphType
{
  public StarWarsQuery()
  {
    var data = new StarWarsData();
    Name = "Query";
    Field<CharacterInterface>(
      "hero",
      resolve: context => data.GetDroidById("3")
    );
  }
}

public class CharacterInterface : InterfaceGraphType
{
  public CharacterInterface()
  {
    Name = "Character";
    Field<NonNullGraphType<StringGraphType>>("id", "The id of the character.");
    Field<NonNullGraphType<StringGraphType>>("name", "The name of the character.");
    Field<ListGraphType<CharacterInterface>>("friends");
  }
}

public class DroidType : ObjectGraphType
{
  public DroidType()
  {
    var data = new StarWarsData();
    Name = "Droid";
    Field<NonNullGraphType<StringGraphType>>("id", "The id of the droid.");
    Field<NonNullGraphType<StringGraphType>>("name", "The name of the droid.");
    Field<ListGraphType<CharacterInterface>>(
        "friends",
        resolve: context => data.GetFriends(context.Source as StarWarsCharacter)
    );
    Interface<CharacterInterface>();
    IsTypeOf = value => value is Droid;
  }
}

Executing a query.

public async Task<string> Execute(
  Schema schema,
  object rootObject,
  string query,
  string operationName = null,
  Inputs inputs = null)
{
  var executer = new DocumentExecuter();
  var writer = new DocumentWriter();

  var result = await executer.ExecuteAsync(schema, rootObject, query, operationName, inputs);
  return writer.Write(result);
}

var schema = new StarWarsSchema();

var query = @"
  query HeroNameQuery {
    hero {
      name
    }
  }
";

var result = await Execute(schema, null, query);

Console.Writeline(result);

// prints
{
  "data": {
    "hero": {
      "name": "R2-D2"
    }
  }
}

Roadmap

Grammar / AST

• Grammar and AST for the GraphQL language should be complete.

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 fragment names
• Unique input field names
• Unique operation names
• Unique variable names
• Variables are input types
• Variables in allowed position

Schema Introspection

• __typename
• __type
  • name
  • kind
  • description
  • fields
  • interfaces
  • possibleTypes
  • enumValues
  • inputFields
  • ofType
• __schema
  • types
  • queryType
  • mutationType
  • subscriptionType
  • directives

Deployment Process

npm run setVersion 0.10.0
write release notes in release-notes.md
git commit/push
download nuget from AppVeyor
upload nuget package to github
upload nuget package to nuget.org