Type Definitions

A TypeDefinition is one unit of GraphQL schema. It provides an SDL string that declares your types, and a resolver map that tells the engine which FieldResolver to call for fields with custom logic.

The Interface

interface TypeDefinition
{
    public function getSdl(): string;
    public function getResolvers(): array;
}

getSdl() returns a GraphQL SDL string. It may define new object types and extend the root Query or Mutation types to add fields:

type Book { id: ID! title: String! }
extend type Query { books: [Book!]! book(id: ID!): Book }

getResolvers() returns a nested array keyed by type name → field name → FieldResolver class-string. Only fields with custom logic need entries; all other fields fall through to default property resolution.

public function getResolvers(): array
{
    return [
        'Query' => [
            'books' => BooksResolver::class,
            'book'  => BookByIdResolver::class,
        ],
    ];
}

Complete Example

<?php

use PHPNomad\GraphQL\Interfaces\TypeDefinition;

final class BookTypeDefinition implements TypeDefinition
{
    public function getSdl(): string
    {
        return <<<'SDL'
        type Book {
            id:    ID!
            title: String!
        }

        extend type Query {
            books:       [Book!]!
            book(id: ID!): Book
        }
        SDL;
    }

    public function getResolvers(): array
    {
        return [
            'Query' => [
                'books' => BooksResolver::class,
                'book'  => BookByIdResolver::class,
            ],
        ];
    }
}

SDL Conventions

The execution engine (e.g. WebonyxGraphQLStrategy) pre-seeds the schema with base Query and Mutation types. Your type definitions should extend them rather than re-define them:

# Correct — extend the base Query type
extend type Query { books: [Book!]! }

# Wrong — do not re-declare Query or Mutation
type Query { books: [Book!]! }

You can declare as many object types as needed in a single getSdl() return value.

Default Property Resolution

For object fields not listed in getResolvers(), the engine falls back to default resolution:

1. If $rootValue is an array, it reads $rootValue['fieldName'].
2. If $rootValue is an object, it reads $rootValue->fieldName (or calls the getter if __get is defined).

This means you only need to write a FieldResolver when the default resolution is not sufficient — for example, when deriving a value from multiple sources or calling a service.

Registering Type Definitions

Register your TypeDefinition classes through an initializer implementing HasTypeDefinitions. The bootstrapper will pass each definition into the active GraphQLStrategy during application boot.