Custom output types

In some special cases, you want to override the GraphQL return type that is attributed by default by GraphQLite.

For instance:

/**
 * @Type(class=Product::class)
 */
class ProductType
{
    /**
     * @Field(name="id")
     */
    public function getId(Product $source): string
    {
        return $source->getId();
    }
}

In the example above, GraphQLite will generate a GraphQL schema with a field id of type string:

type Product {
    id: String!
}

GraphQL comes with an ID scalar type. But PHP has no such type. So GraphQLite does not know when a variable is an ID or not.

You can help GraphQLite by manually specifying the output type to use:

    /**
     * @Field(name="id", outputType="ID!")
     */

Usage

The outputType attribute will map the return value of the method to the output type passed in parameter.

You can use the outputType attribute in the following annotations:

• @Query
• @Mutation
• @Field
• @SourceField

Registering a custom output type (advanced)

In order to create a custom output type, you need to:

1. Design a class that extends GraphQL\Type\Definition\ObjectType.
2. Register this class in the GraphQL schema.

You'll find more details on the Webonyx documentation.

---

In order to find existing types, the schema is using type mappers (classes implementing the TypeMapperInterface interface).

You need to make sure that one of these type mappers can return an instance of your type. The way you do this will depend on the framework you use.

Symfony users

Any class extending GraphQL\Type\Definition\ObjectType (and available in the container) will be automatically detected by Symfony and added to the schema.

If you want to automatically map the output type to a given PHP class, you will have to explicitly declare the output type as a service and use the graphql.output_type tag:

# config/services.yaml
services:
    App\MyOutputType:
        tags:
            - { name: 'graphql.output_type', class: 'App\MyPhpClass' }

Other frameworks

The easiest way is to use a StaticTypeMapper. This class is used to register custom output types.

// Sample code:
$staticTypeMapper = new StaticTypeMapper();

// Let's register a type that maps by default to the "MyClass" PHP class
$staticTypeMapper->setTypes([
    MyClass::class => new MyCustomOutputType()
]);

// If you don't want your output type to map to any PHP class by default, use:
$staticTypeMapper->setNotMappedTypes([
    new MyCustomOutputType()
]);

The StaticTypeMapper instance MUST be registered in your container and linked to a CompositeTypeMapper that will aggregate all the type mappers of the application.