From 8fe3e456f9ea4cbb9b583b4e0a4e3ab365d76c43 Mon Sep 17 00:00:00 2001
From: David de Boer <david@ddeboer.nl>
Date: Fri, 21 Aug 2026 13:57:39 +0200
Subject: [PATCH] fix(dataset-registry-client): type the IRI-valued schema
 properties as IRIs

- Declare '@type': ldkit.IRI on license, accessURL, mediaType,
  compressFormat and conformsTo, which hold IRIs in DCAT-AP. Without it
  LDkit falls back to xsd:string and encodes a search value as a plain
  literal, so a filter such as mediaType $in [...] compares an IRI to a
  string and can never match.
- The mismatch was invisible because LDkit emitted a search FILTER inside
  the OPTIONAL block of an optional property, where it only unbound the
  value instead of removing the row; ldkit 2.7.2 hoists the FILTER out of
  the block and makes it bite.
- Cover a distribution that declares no media type through an $id query:
  media-type criteria now narrow a dataset's distributions to the
  matching ones, so a filtered query no longer reaches that path.
---
 .../dataset-registry-client/src/schema.ts     | 11 ++++++++--
 .../test/client.test.ts                       | 20 +++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/packages/dataset-registry-client/src/schema.ts b/packages/dataset-registry-client/src/schema.ts
index 2c95a6d5..1a153916 100644
--- a/packages/dataset-registry-client/src/schema.ts
+++ b/packages/dataset-registry-client/src/schema.ts
@@ -1,4 +1,4 @@
-import { dcterms, foaf, xsd } from 'ldkit/namespaces';
+import { dcterms, foaf, ldkit, xsd } from 'ldkit/namespaces';
 import { dcat } from './dcat.js';
 
 export const DatasetSchema = {
@@ -19,6 +19,7 @@ export const DatasetSchema = {
   },
   license: {
     '@id': dcterms.license,
+    '@type': ldkit.IRI,
     '@optional': true,
   },
   creator: {
@@ -47,9 +48,13 @@ export const DatasetSchema = {
     '@array': true,
     '@schema': {
       '@type': dcat.Distribution,
-      accessURL: dcat.accessURL,
+      accessURL: {
+        '@id': dcat.accessURL,
+        '@type': ldkit.IRI,
+      },
       mediaType: {
         '@id': dcat.mediaType,
+        '@type': ldkit.IRI,
         '@optional': true,
       },
       byteSize: {
@@ -59,10 +64,12 @@ export const DatasetSchema = {
       },
       compressFormat: {
         '@id': dcat.compressFormat,
+        '@type': ldkit.IRI,
         '@optional': true,
       },
       conformsTo: {
         '@id': dcterms.conformsTo,
+        '@type': ldkit.IRI,
         '@optional': true,
       },
       modified: {
diff --git a/packages/dataset-registry-client/test/client.test.ts b/packages/dataset-registry-client/test/client.test.ts
index 5bdc3d83..29e34e4e 100644
--- a/packages/dataset-registry-client/test/client.test.ts
+++ b/packages/dataset-registry-client/test/client.test.ts
@@ -100,6 +100,26 @@ describe('Client', () => {
       expect(count).toEqual(1);
     });
 
+    it('reads back a distribution that declares no media type', async () => {
+      // Only reachable without media-type criteria: those narrow a dataset’s
+      // distributions to the matching ones, so a filtered query never returns
+      // this distribution.
+      const results = await client.query({
+        $id: 'http://bar.org/id/dataset/bar',
+      });
+
+      const mediaTypes = [];
+      for await (const dataset of results) {
+        mediaTypes.push(
+          ...dataset.distributions.map(
+            (distribution) => distribution.mediaType,
+          ),
+        );
+      }
+
+      expect(mediaTypes).toContain(undefined);
+    });
+
     it('throws an error for non-CONSTRUCT queries', async () => {
       const query = `
         PREFIX dcat: <http://www.w3.org/ns/dcat#>