Architecture Overview
High-level architecture of the Native Content Relationships plugin.
System components
- Core: Public API (
ncr_add_relation,ncr_get_related, etc.) → Relationship Type Registry → Database (wp_content_relations) + Object Cache - Integrity: WP-CLI / scheduled tasks → Repair logic → Schema and constraint checks → reads/writes DB
- Interfaces: Admin meta box, REST API, Elementor Dynamic Tags, Gutenberg block — all use the Public API
Key components
1. Registry layer
Defines allowed relationship types and their constraints: max_connections, direction, object_types. Implemented in the relation-types layer.
2. Database layer
- Table:
wp_content_relations - Indexes: Composite on
(from_id, type)and(to_id, type); covering index on(type, from_id, to_id). - Schema guard:
NCR_SCHEMA_VERSIONensures DB updates run only when needed.
See Schema.
3. Integrity engine
- Chunked processing for large datasets (1M+ rows)
- Orphan detection (relations to deleted posts/users)
- Constraint enforcement (e.g. max_connections)
4. Public API
Facade for create/read/remove; validates against the registry and uses object cache where appropriate.