extract query logic for latest date container to dedicated query class

Author: angelo-v

chats/rdflib/src/module/ChatsModuleRdfLib.ts

@@ -11,7 +11,8 @@ import {
 import { generateId } from "@solid-data-modules/rdflib-utils/identifier";
 import { createChat } from "./update-operations/index.js";
 import { ChatQuery } from "./queries/index.js";
-import { MessagesDocumentQuery } from './queries/MessagesDocumentQuery.js';
+import { MessagesDocumentQuery } from "./queries/MessagesDocumentQuery.js";
+import { DateContainerQuery } from "./queries/DateContainerQuery.js";
 
 interface ModuleConfig {
   store: IndexedFormula;
@@ -62,7 +63,11 @@ export class ChatsModuleRdfLib implements ChatsModule {
     if (!latestYear) return [];
 
     const latestMonth = await this.fetchLatestSubContainer(latestYear);
+    if (!latestMonth) return [];
+
     const latestDay = await this.fetchLatestSubContainer(latestMonth);
+    if (!latestDay) return [];
+
     const messagesDocument = await this.fetchLatestDocument(latestDay);
 
     return new MessagesDocumentQuery(
@@ -74,17 +79,7 @@ export class ChatsModuleRdfLib implements ChatsModule {
 
   private async fetchLatestSubContainer(container: NamedNode) {
     await this.support.fetchNode(container);
-
-    const contents = new ContainerQuery(container, this.store).queryContents();
-    const childContainers = contents.filter((it) => {
-      return this.store.holds(
-        it,
-        rdf("type"),
-        ldp("Container"),
-        container.doc(),
-      );
-    });
-    return childContainers[0]; // TODO actually get latest
+    return new DateContainerQuery(container, this.store).queryLatest();
   }
 
   private async fetchLatestDocument(container: NamedNode) {

chats/rdflib/src/module/queries/DateContainerQuery.spec.ts

@@ -0,0 +1,72 @@
+import { DateContainerQuery } from "./DateContainerQuery";
+import { graph, sym } from "rdflib";
+
+describe(DateContainerQuery.name, () => {
+  describe("query latest", () => {
+    it("returns null if store is empty", () => {
+      const store = graph();
+      const result = new DateContainerQuery(
+        sym("https://pod.test/container/"),
+        store,
+      ).queryLatest();
+      expect(result).toBe(null);
+    });
+
+    it("returns the only container", () => {
+      const store = graph();
+      store.add(
+        sym("https://pod.test/container/"),
+        sym("http://www.w3.org/ns/ldp#contains"),
+        sym("https://pod.test/container/2024/"),
+        sym("https://pod.test/container/"),
+      );
+      store.add(
+        sym("https://pod.test/container/2024/"),
+        sym("http://www.w3.org/1999/02/22-rdf-syntax-ns#type"),
+        sym("http://www.w3.org/ns/ldp#Container"),
+        sym("https://pod.test/container/"),
+      );
+      const result = new DateContainerQuery(
+        sym("https://pod.test/container/"),
+        store,
+      ).queryLatest();
+      expect(result).toEqual(sym("https://pod.test/container/2024/"));
+    });
+
+    it("returns null if all contents are not containers", () => {
+      const store = graph();
+      store.add(
+        sym("https://pod.test/container/"),
+        sym("http://www.w3.org/ns/ldp#contains"),
+        sym("https://pod.test/container/2024"),
+        sym("https://pod.test/container/"),
+      );
+
+      const result = new DateContainerQuery(
+        sym("https://pod.test/container/"),
+        store,
+      ).queryLatest();
+      expect(result).toEqual(null);
+    });
+    it("returns null if container type is in wrong document", () => {
+      const store = graph();
+      store.add(
+        sym("https://pod.test/container/"),
+        sym("http://www.w3.org/ns/ldp#contains"),
+        sym("https://pod.test/container/2024/"),
+        sym("https://pod.test/container/"),
+      );
+      store.add(
+        sym("https://pod.test/container/2024/"),
+        sym("http://www.w3.org/1999/02/22-rdf-syntax-ns#type"),
+        sym("http://www.w3.org/ns/ldp#Container"),
+        sym("https://pod.test/wrong/"),
+      );
+      const result = new DateContainerQuery(
+        sym("https://pod.test/container/"),
+        store,
+      ).queryLatest();
+      expect(result).toEqual(null);
+    });
+  });
+});

chats/rdflib/src/module/queries/DateContainerQuery.ts

@@ -0,0 +1,25 @@
+import { IndexedFormula, NamedNode } from "rdflib";
+import { ContainerQuery, ldp, rdf } from "@solid-data-modules/rdflib-utils";
+
+export class DateContainerQuery {
+  constructor(
+    private container: NamedNode,
+    private store: IndexedFormula,
+  ) {}
+
+  queryLatest(): NamedNode | null {
+    const contents = new ContainerQuery(
+      this.container,
+      this.store,
+    ).queryContents();
+    const childContainers = contents.filter((it) => {
+      return this.store.holds(
+        it,
+        rdf("type"),
+        ldp("Container"),
+        this.container.doc(),
+      );
+    });
+    return childContainers[0] ?? null; // TODO actually get latest
+  }
+}