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.

v1.0.0
Datopian
MIT

Allowed Tools

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portaljs

Agentic skills for building PortalJS data portals — recommend an architecture, scaffold a portal, add datasets, charts, and maps, connect a CKAN backend, deploy, and audit data quality.

community v0.1.0
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Installation

This skill is included in the portaljs plugin:

/plugin install portaljs@claude-code-plugins-plus

Click to copy

Instructions

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:

  1. Gather input from $ARGUMENTS (interview if thin): portal directory (default .),

profiles (default ["dcat-3"]), site URL, publisher, contact, license, themes,

languages, access level.

  1. Validate the portal directory: confirm datasets.json, package.json, and

lib/metadata/ exist; stop with an ERROR: if the metadata contract is missing.

  1. 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.

  1. Ensure scripts/generate-dcat.ts is wired to predev/prebuild and emits

per-profile x serialization feeds from dcat.config.json.

  1. Write dcat.config.json with the gathered profiles, publisher, contact, license,

themes, and access level.

  1. Add feed autodiscovery: a to

pages/_document.tsx pointing at /catalog.jsonld.

  1. Generate the feeds and check conformance: run npm run generate:dcat and surface

any missing mandatory fields.

  1. 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.

  1. Verify the build with npx next build; fix errors before reporting success.
  2. 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..{jsonld,ttl,rdf} per configured profile,

public/catalog-feeds.json (feed index).

  • Modified: pages/_document.tsx (autodiscovery ), 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
NOMETADATACONTRACT lib/metadata/ not found Portal predates the metadata-profile contract; scaffold with portaljs-new-portal or add lib/metadata first.
NODCATCORE 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

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