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OpenAPI & GraphQL APIs

Overview​

OpenRegister auto-generates complete OpenAPI 3.1.0 specifications and a GraphQL API from register and schema definitions at runtime. This means API documentation is always in sync with the live data model — no manual maintenance, no drift. Both APIs reuse the same underlying services for RBAC enforcement, relation resolution, and search.

OpenAPI Generation​

Auto-Generated Specification​

For each register, OpenRegister generates a complete OpenAPI 3.1.0 specification covering:

  • All CRUD endpoints for every schema in the register
  • Query parameters for search (_search), filtering, sorting, pagination, and facets
  • Request and response schemas derived from JSON Schema property definitions
  • Authentication schemes (session, bearer token, OAuth2)
  • RBAC scopes per operation (group-based, from schema authorization blocks)
  • Example payloads using x-openapi-examples
  • NL API Design Rules compliance markers

Download Formats​

GET /api/registers/{id}/oas            OpenAPI JSON (default)
GET /api/registers/{id}/oas?format=yaml    OpenAPI YAML
GET /api/registers/{id}/oas/ui         Swagger UI (interactive browser)

A combined spec covering all registers is available at:

GET /api/oas                           Combined OpenAPI spec for all registers

JSON Schema to OpenAPI Type Mapping​

JSON SchemaOpenAPI
type: stringtype: string
type: string, format: datetype: string, format: date
type: string, format: date-timetype: string, format: date-time
type: string, format: uuidtype: string, format: uuid
type: integertype: integer
type: numbertype: number, format: float
type: booleantype: boolean
type: arraytype: array, items: ...
type: object$ref: #/components/schemas/...
enum: [...]type: string, enum: [...]

RBAC Scopes in OAS​

Authorization blocks from schema definitions are extracted into components.securitySchemes:

components:
  securitySchemes:
    oauth2:
      type: oauth2
      flows:
        authorizationCode:
          scopes:
            juridisch-team: "Access to bezwaarschriften schema"
            admin: "Administrative access"
paths:
  /api/objects/register/bezwaarschriften:
    get:
      security:
        - oauth2: [juridisch-team]
    delete:
      security:
        - oauth2: [admin]

Auto-Regeneration​

The spec regenerates automatically when:

  • A schema property is added, changed, or removed
  • Schema authorization blocks are updated
  • A new schema is added to a register

A background job keeps a cached spec version to avoid regeneration on every request.

OAS Validation​

Generated specs are validated against the OpenAPI 3.1.0 schema before serving. Validation failures are logged and the last valid spec is returned. Schema authors are notified of validation errors via Nextcloud notifications.

GraphQL API​

Auto-Generated Schema​

The GraphQL schema is derived dynamically from register schema definitions at runtime. SchemaGenerator.generate() iterates all registers and schemas and builds corresponding GraphQL types.

Type Generation​

For each schema, SchemaGenerator creates:

  • A GraphQL ObjectType (PascalCase name, singularized from schema slug)
  • Query fields: {schema}List(filter, sort, pagination) and {schema}(id) for single-object lookup
  • Mutation fields: create{Schema}, update{Schema}, delete{Schema}
  • Subscription fields: {schema}Events for real-time updates via SSE
type Meldingen {
  _uuid: UUID!
  _created: DateTime
  _updated: DateTime
  _owner: String
  titel: String
  status: String
  prioriteit: Int
}

type Query {
  meldingenList(filter: MeldingenFilter, sort: MeldingenSort, first: Int, after: String): MeldingenConnection
  melding(id: UUID!): Meldingen
}

type Mutation {
  createMelding(input: MeldingenInput!): Meldingen
  updateMelding(id: UUID!, input: MeldingenInput!): Meldingen
  deleteMelding(id: UUID!): Boolean
}

type Subscription {
  meldingenEvents(filter: MeldingenFilter): MeldingenEvent
}

Nested Relation Resolution​

Properties with $ref to other schemas generate nested GraphQL types. RelationHandler resolves referenced objects with DataLoader batching to avoid N+1 queries:

query {
  meldingenList(filter: { status: "nieuw" }) {
    nodes {
      _uuid
      titel
      behandelaar {  # resolved from UUID reference
        naam
        email
      }
    }
  }
}

RBAC in GraphQL​

GraphQL resolvers reuse the same authorization stack as the REST API:

  • PermissionHandler for schema-level RBAC
  • PropertyRbacHandler for field-level security (unauthorized fields return null)
  • MagicRbacHandler for row-level SQL conditions

Query Complexity Analysis​

QueryComplexityAnalyzer prevents abuse by rejecting queries that exceed a configurable complexity score. Deeply nested queries with large pagination are rejected with HTTP 400 before execution.

GraphQL Endpoint​

POST /api/graphql           Execute a GraphQL query, mutation, or subscription
GET  /api/graphql           GraphQL playground (introspection UI)
GET  /api/graphql/schema    Download the GraphQL SDL schema

Subscriptions via SSE​

GraphQL subscriptions are delivered over Server-Sent Events:

GET /api/graphql/subscriptions?query=subscription{meldingenEvents{_uuid,titel,status}}

The SubscriptionService maintains an in-memory event buffer per subscription. The GraphQLSubscriptionListener bridges Nextcloud PHP events into the SSE buffer.

NL API Design Rules​

All generated REST endpoints comply with the NL API Design Rules:

  • Resource-based URL structure (/api/objects/{register}/{schema})
  • HTTP methods follow REST semantics (GET, POST, PUT, PATCH, DELETE)
  • Pagination via _start/_limit and Link headers
  • Versioning via URL path (/api/v1/...) or API-Version header
  • Error responses follow Problem Details (RFC 7807)
  • Dutch field names supported alongside English aliases

Standards​

StandardRole
OpenAPI 3.1.0REST API specification format
GraphQL (June 2018)Query language and execution engine
NL API Design RulesDutch government API conventions
OAuth2Scope model in OAS security definitions
RFC 7807Problem Details for HTTP APIs (error format)