GraphQL.Tools

GraphQL.Tools is a GraphQL to C# compiler (code-generator) which turns your GraphQL schema into a set of C# classes, interfaces, and enums.

Features 🌀

1. GraphQL type to C# class compiler
2. GraphQL interface to C# interface compiler
3. GraphQL argument to C# class compiler
4. GraphQL union to C# class compiler
5. GraphQL enum to C# enum compiler
6. Proper C# nullable support

Getting Started

1. Installing GraphQL.Tools

You can install GraphQL.Tools with NuGet Package Manager Console:

Install-Package GraphQL.Tools

Or via the .NET Core command-line interface:

dotnet add package GraphQL.Tools

Either commands, from Package Manager Console or .NET Core CLI, will download and install GraphQL.Tools and all required dependencies.

2. Defining your GraphQL schema

* Important: GraphQL.Tools just accepts .gql and .graphql as valid extensions for GraphQL schema files.

Create a new file called Sample.gql in the root of your project. This is a simple GraphQL schema that demonstrates most of the GraphQL features which you can access it here from the sample project too:

type Query {
    getSimple(name: String!): Simple!
    
    simple: Simple!
    simples: [Simple]!
    nullableSimples: [Simple!]

    identity: Identity!
}

# -----------------------------------------------------------

type Simple {
    bool: Boolean!
    int32: Int!
    float: Float!
    double: Float!
    string: String!
}

# -----------------------------------------------------------

union Identity = EmailIdentity | PhoneNumberIdentity

type EmailIdentity {
    value: String!
}

type PhoneNumberIdentity {
    value: Float!
}

# -----------------------------------------------------------

enum Color {
  RED
  GREEN
  BLUE
}

# -----------------------------------------------------------

interface Character {
  id: Int!
  name: String!
}

type Human implements Character {
  id: Int!
  name: String!
  totalCredits: Int
}
 
type Droid implements Character {
  id: Int!
  name: String!
  primaryFunction: String
}

3. Configuring GraphQL source generator

Open your project .csproj file and add a new ItemGroup section to it that contains a GraphQL element:

<ItemGroup>
    <GraphQL Include="$(ProjectDir)Sample.gql" AdditionalNamespaces="System" Visitors="Class, Interface, Enum, Union, Argument" />
</ItemGroup>

In this example:

• Include is the absolute path to our previously created GraphQL schema file that ends with .gql or .graphql.
• AdditionalNamespaces are the comma-separated namespaces that need to be included in the generated file to compile properly (Custom types namespaces like DateTime, TimeSpan, ...).
• Visitors are the comma-separated name of generators (parsers) that should visit the provided schema file. Currently, these are available visitors:
  • 1. Class
  • 2. Interface
  • 3. Enum
  • 4. Union
  • 5. Argument

4. Done, build the project!

After doing these steps, everything is fine now. Just compile and build the project. The C# file will be generated like this:

using System;

#nullable enable annotations
namespace GraphQL.Tools
{
    public partial class Generated
    {
	public class Query
        {
	    public Simple GetSimple { get; set; }
	    public Simple Simple { get; set; }
	    public Simple[] Simples { get; set; }
	    public Simple[]? NullableSimples { get; set; }
	    public Identity Identity { get; set; }
        }

	// -----------------------------------------------------------

	public class Simple
        {
	    public bool Bool { get; set; }
	    public int Int32 { get; set; }
	    public float Float { get; set; }
	    public float Double { get; set; }
	    public string String { get; set; }
        }

	// -----------------------------------------------------------

	public class Identity
        {
	    public EmailIdentity? EmailIdentity { get; set; }
	    public PhoneNumberIdentity? PhoneNumberIdentity { get; set; }
        }

	public class EmailIdentity
        {
	    public string Value { get; set; }
        }

	public class PhoneNumberIdentity
        {
	    public float Value { get; set; }
        }

	// -----------------------------------------------------------

	public enum Color
        {
	    RED,
	    GREEN,
	    BLUE
        }

	// -----------------------------------------------------------

	public interface Character
        {
	    public int Id { get; set; }
	    public string Name { get; set; }
        }

        public class Human : Character
        {
	    public int Id { get; set; }            
	    public string Name { get; set; }
	    public int? TotalCredits { get; set; }
        }

        public class Droid : Character
        {
	    public int Id { get; set; }
	    public string Name { get; set; }
	    public string? PrimaryFunction { get; set; }
        }

	// -----------------------------------------------------------

        public class Query_GetSimple_Arguments
        {
	    public string Name { get; set; }
        }
    }
}

* Side Note: You can view the generated file in $(ProjectDir)\obj\Generated\GraphQL.Tools\GraphQL.Tools.GraphqlCodeGenerator\GraphQL.Tools.g.cs by adding these elements to the PropertyGroup of your .csproj file:

<EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
<CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)Generated</CompilerGeneratedFilesOutputPath>

5. Use the generated source in your project

Now you can use the generated file in your project:

internal class Program
{
    private static void Main()
    {
        var simple = new GraphQL.Tools.Generated.Simple
        {
            Bool = true,
            Int32 = 1,
            Float = 3.5F,
            Double = 1.234F,
            String = "Hello World!"
        };

        Console.WriteLine(@$"{simple.Bool}, {simple.Int32}, {simple.Float}, {simple.Double}, {simple.String}");
    }
}

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