WPGraphQL Federations

WPGraphQL Federations is a WordPress plugin that adds Apollo Federation v2 support to WPGraphQL. It allows your WordPress site to function as a subgraph in a federated GraphQL architecture, enabling seamless integration with other microservices.

🚀 The Problem

In modern microservices architectures, teams often use GraphQL Federation to combine multiple GraphQL services (subgraphs) into a single, unified gateway (supergraph).

While WordPress is a powerful CMS and WPGraphQL provides an excellent API, it does not support Apollo Federation out of the box. Specifically:

• It lacks the required _service and _entities root fields.
• It doesn't support Federation directives like @key, @shareable, or @external.
• It cannot resolve entities based on their representation objects (e.g., resolving a Post by its ID from another service).

This makes it difficult to include WordPress in a larger federated ecosystem without complex custom code or brittle middleware.

✨ The Solution

WPGraphQL Federations bridges this gap by transforming WPGraphQL into a fully compliant Apollo Federation subgraph. It provides:

1. Automatic Entity Discovery: Detects your Post Types, Taxonomies, Users, and Comments and makes them available as federated entities.
2. Runtime Registry: A management interface to configure Federation v2 directives (@key, @shareable, etc.) for any GraphQL type or field.
3. Entity Resolution: Automatically handles the _entities query, allowing other services to "join" data with WordPress objects using global IDs or custom keys.
4. Schema Augmentation: Injects the necessary Federation scalars and types into the schema and provides the full SDL with directives via the _service field.

🛠 Features

• Full Federation v2 Support: Implements the latest Apollo Federation specification.
• Admin Settings Page: A user-friendly interface in the WordPress dashboard to manage federation settings.
• Type-Level Directives: Configure @key, @shareable, and @inaccessible for any Object Type.
• Field-Level Directives: Apply @external, @requires, @provides, @override, and @tag to specific fields.
• Flexible Keys: Support for both standard Relay Global IDs and internal database IDs as entity keys.
• Custom Directives: Support for adding additional custom directives to types.

📦 Installation

1. Upload the wp-graphql-federations folder to the /wp-content/plugins/ directory.
2. Activate the plugin through the 'Plugins' menu in WordPress.
3. Ensure WPGraphQL is also installed and active.
4. Run composer install in the plugin directory to ensure the autoloader is generated (if using the composer version).

⚙️ Configuration

Once activated, go to Settings > WPGraphQL Federation in your WordPress admin.

1. Enable Types: Select the GraphQL types (Post Types, Users, etc.) you want to expose as entities.
2. Define Keys: Specify the @key fields (usually id) that the gateway will use to identify these entities.
3. Field Directives: Expand the "Manage Fields" section for any type to apply field-specific federation logic.
4. Save Changes: The plugin will automatically update the schema and SDL.

🔍 Technical Implementation

Entity Resolution

The plugin implements a robust resolve_entity method that understands how to fetch WordPress objects based on the __typename and key provided by the gateway. It supports:

• Post Types: Posts, Pages, and any custom post types.
• Taxonomies: Categories, Tags, and custom taxonomies.
• Core Entities: Users and Comments.

SDL Generation

The plugin hooks into graphql_schema_config and graphql_register_types to inject:

• scalar _Any and scalar _FieldSet
• type _Service { sdl: String }
• union _Entity (containing all your enabled federated types)
• _service and _entities root queries.

📋 Requirements

• PHP: 7.4 or higher
• WordPress: 5.0 or higher
• WPGraphQL: 1.0 or higher

📄 License

This project is licensed under the MIT License.

Created by Manuel Antunes