portaljs-add-dcat

Make a PortalJS portal harvestable by national/EU/US open-data portals — emit standards-compliant DCAT catalog feeds (DCAT 2/3, DCAT-AP, DCAT-US, national profiles) in JSON-LD, Turtle, and RDF/XML at build, with autodiscovery and per-profile conformance checking. Use when a portal needs to be harvested by data.europa.eu, data.gov, or a national open-data catalog.

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PortalJS — Add DCAT

Overview

Turn an existing PortalJS (portaljs-catalog) portal into a harvestable data catalog. PortalJS is Frictionless-native — a dataset is a Data Package (see portaljs-define-schema) — and DCAT is the serialization + harvest layer on top (lib/metadata/dcat.ts + lib/metadata/dcat-profiles.ts). This skill selects one or more DCAT application profiles, maps every dataset's metadata to them, and writes static feed files at build time — JSON-LD, Turtle, and RDF/XML — so external catalogs (data.europa.eu, data.gov, national portals) can harvest the datasets automatically, on any static host, with no runtime.

Prerequisites

A scaffolded PortalJS portal with datasets.json, package.json, and lib/metadata/ (the metadata-profile contract) present.
lib/metadata/dcat.ts (the DCAT-3 core) already in place — profiles augment it.
Node 18+ and npm available in the portal directory.
For DCAT-AP / DCAT-US: a publishing organization (name + homepage) and a contact (name + email) — both profiles require dct:publisher and dcat:contactPoint.
Optional but recommended: network access to run SHACL conformance checks against the official EU ITB validator or pyshacl.

Instructions

The canonical, full step-by-step workflow is .claude/commands/portaljs-add-dcat.md — the single source of truth. Read and follow it when executing. Summary:

Gather input from $ARGUMENTS (interview if thin): portal directory (default .), profiles (default ["dcat-3"]), site URL, publisher, contact, license, themes, languages, access level.
Validate the portal directory: confirm datasets.json, package.json, and lib/metadata/ exist; stop with an ERROR: if the metadata contract is missing.
Ensure the DCAT profile layer is present — dcat-profiles.ts, dcat-rdf.ts, dcat-validate.ts — copying canonical versions from examples/portaljs-catalog if the portal predates this skill.
Ensure scripts/generate-dcat.ts is wired to predev/prebuild and emits per-profile x serialization feeds from dcat.config.json.
Write dcat.config.json with the gathered profiles, publisher, contact, license, themes, and access level.
Add feed autodiscovery: a <link rel="alternate" type="application/ld+json"> to pages/_document.tsx pointing at /catalog.jsonld.
Generate the feeds and check conformance: run npm run generate:dcat and surface any missing mandatory fields.
Verify the RDF: confirm the JSON-LD parses, and cross-check that JSON-LD, Turtle, and RDF/XML agree; run SHACL validation (ITB for DCAT-AP, pyshacl for DCAT-US) when network/tooling allow.
Verify the build with npx next build; fix errors before reporting success.
Report the profiles emitted, feed paths, conformance status, and next steps (register with the harvester, run portaljs-deploy).

Output

Created/modified: dcat.config.json (committed config).
Generated (build artifacts, gitignored): public/catalog.jsonld /.ttl/.rdf (canonical feed), public/catalog.<profile>.{jsonld,ttl,rdf} per configured profile, public/catalog-feeds.json (feed index).
Modified: pages/_document.tsx (autodiscovery <link>), package.json (generate:dcat script wired to predev/prebuild).
Verified: feeds are valid JSON-LD/Turtle/RDF-XML, conformance status reported, npx next build passes.

Error Handling

Symptom	Cause	Fix
`NO_METADATA_CONTRACT`	`lib/metadata/` not found	Portal predates the metadata-profile contract; scaffold with `portaljs-new-portal` or add `lib/metadata` first.
`NO_DCAT_CORE`	`lib/metadata/dcat.ts` not found	The DCAT-3 core is missing; update the portal template before adding profiles.
`BAD_CONFIG`	`dcat.config.json` is not valid JSON	Fix the syntax and re-run `npm run generate:dcat`.
`UNKNOWN_PROFILE`	Profile id not in the registry	Use one of `dcat-2`, `dcat-3`, `dcat-ap`, `dcat-us`, `geodcat-ap`, `croissant`, `dcat-ap-se`, `dcat-ap-ch`, `dcat-ap-de`, or register a national profile first.
Feed flagged non-conformant	`publisher`/`contactPoint` missing for DCAT-AP or DCAT-US	Ask the user for the publishing organization and contact, add to `dcat.config.json`, regenerate.
DCAT-US SHACL rejects the publisher	Publisher has no IRI (blank node)	Set `publisher.uri` (or `homepage`) in `dcat.config.json`.
`next build` fails after config change	Malformed JSON in `dcat.config.json` or `datasets.json`	Print the build log, fix the JSON, rebuild before reporting success.

Examples

Example 1 — Default DCAT-3 feed, no national harvesting

/portaljs-add-dcat

Emits the canonical public/catalog.jsonld/.ttl/.rdf under the default dcat-3 profile, adds autodiscovery to _document.tsx, and wires generate:dcat into predev/prebuild. No publisher/contact required.

Example 2 — EU harvesting via DCAT-AP

/portaljs-add-dcat profiles=dcat-ap site=https://data.example.org

Prompts for publisher (name + homepage) and contact (name + email) since DCAT-AP requires both, writes them into dcat.config.json, and emits public/catalog.dcat-ap.{jsonld,ttl,rdf} plus the canonical feed with absolute links.

Example 3 — US federal harvesting via DCAT-US

/portaljs-add-dcat profiles=dcat-us site=https://data.example.gov

Requires an IRI-identified publisher (publisher.uri) for SHACL conformance; emits catalog.dcat-us.{jsonld,ttl,rdf} and validates against the DCAT-US 3.0 SHACL shapes with pyshacl when available.

Example 4 — Multiple profiles plus a national extension

/portaljs-add-dcat profiles=dcat-ap,dcat-ap-de site=https://daten.example.de

Emits both catalog.dcat-ap.* and catalog.dcat-ap-de.* feeds from one config; the first profile listed also becomes the canonical, un-suffixed catalog.jsonld/.ttl/.rdf.

Resources

Full workflow: .claude/commands/portaljs-add-dcat.md
Profile registry, serialization formats, and validator details: references/reference.md
Related skills: portaljs-define-schema, portaljs-new-portal, portaljs-deploy, portaljs-migrate
DCAT specification: https://www.w3.org/TR/vocab-dcat-3/

Repository: datopian/portaljs
Path: skills/portaljs-add-dcat/SKILL.md
Commit: ebfd391

Last updated: 7 days ago
First committed: ~2 months ago

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