graphql-schema-declare

An elegant and simple way to declare your graphql queries and mutations with a single line.

Example

The old way 😵

public class StarWarsMutation : ObjectGraphType
{
  public StarWarsMutation(StarWarsData data)
  {
    Field<HumanType>(
      "createHuman",
      arguments: new QueryArguments(
        new QueryArgument<NonNullGraphType<HumanInputType>> {Name = "human"}
      ),
      resolve: context =>
      {
        var human = context.GetArgument<Human>("human");
        return data.AddHuman(human);
      });
  }
}

The elegant way using SchemaDeclare 😍

using GraphQL.SchemaDeclare;

public class StarWarsController
{
	StarWarsData data;

	public StarWarsController(StarWarsData data) => this.data = data;

	public Human CreateHuman([Required]HumanInput human) => data.AddHuman(new Human() { Name = human.Name });
}

public class StarWarsMutation : ObjectGraphType
{
  public StarWarsMutation()
  {
	this.Mutation<StarWarsController>(c => c.CreateHuman(default));
  }
}

Getting started

Installation

PM> Install-Package GraphQL.SchemaDeclare

Usage

Add the following namespace where you wanna use the extension methods :

using GraphQL.SchemaDeclare;

Then in your query/mutation construction you can use :

public class StarWarsMutation : ObjectGraphType
{
  public StarWarsMutation()
  {
	this.Mutation<StarWarsController>(c => c.CreateHuman(default));
	this.MutationAsync<StarWarsController>(c => c.CreateHumanAsync(default));
	this.Mutation<StarWarsController>("anotherCreateHuman", c => c.CreateHuman(default));
  }
}

public class StarWarsQuery : ObjectGraphType
{
  public StarWarsQuery()
  {
	this.Query<StarWarsController>(c => c.GetHuman(default));
	this.QueryAsync<StarWarsController>(c => c.GetHumanAsync(default));
	this.Query<StarWarsController>("anotherGetHuman", c => c.GetHuman(default));
  }
}

🚨 Don't forget to register your complex type using GraphTypeTypeRegistry.Register

Example :

GraphTypeTypeRegistry.Register<Human, HumanType>();
GraphTypeTypeRegistry.Register<HumanInput, HumanInputType>();

You can add the [Required] attribute on method parameters to force non null parameter on reference type.

DependencyInjection

To use dependency injection in your controller, you must set ObjectGraphTypeExtensions.DependencyResolver and register :

• ITypeToGraphTypeTransformer
• IFieldInfoToFieldTypeTransformer
• IExpressionToFieldInfoGenerator
• IFieldInfoResolver

Example :

public void ConfigureServices(IServiceCollection services)
{
	// Register 
	serviceCollection.AddGraphQLSchemaDeclareService();

  // By default the Type to GraphType transformer option's AddNullableInfo is set to True
  // You can set its value to False by passing it to service declaration:
  // serviceCollection.AddGraphQLSchemaDeclareService(_ => _.AddNullableInfo = false);

}

public virtual void Configure(IApplicationBuilder app, IWebHostEnvironment env, Microsoft.Extensions.Logging.ILoggerFactory loggerFactory)
{
	// Set DependencyResolver
	GraphQL.SchemaDeclare.ObjectGraphTypeExtensions.ServiceProvider = app.ApplicationServices;
}

How does it works

We read the expression in argument to discover :

• Method name : used as field name
• Argument name : used as query argument name
• Argument type : Converted using TypeToGraphTypeTransformer and using mostly GraphTypeTypeRegistry
• Return type : used as field type

Value types are marked as NonNullGraphType unless nullable (see : TypeToGraphTypeTransformerTests). Reference types can be generated as NonNullGraphType if you add the attribute [Required] on the parameter.