perf(workbooks): fetch only referenced tasks on CURRICULUM tab instead of all tasks

src/features/workbooks/utils/workbooks.test.ts

@@ -9,6 +9,7 @@ import {
   getUrlSlugFrom,
   getWorkBooksByType,
   buildTaskResultsByWorkBookId,
+  buildTaskIdsFromWorkbooks,
   calcWorkBookGradeModes,
   getGradeMode,
   getTaskResult,
@@ -179,6 +180,44 @@ describe('Workbooks', () => {
     });
   });
 
+  describe('buildTaskIdsFromWorkbooks', () => {
+    test('returns unique task ids deduplicated across workbooks', () => {
+      const workbooks = [
+        createWorkBookListBase({
+          id: 1,
+          workBookTasks: [
+            { taskId: 'abc300_a', priority: 1, comment: '' },
+            { taskId: 'abc300_b', priority: 2, comment: '' },
+          ],
+        }),
+        createWorkBookListBase({
+          id: 2,
+          workBookTasks: [
+            { taskId: 'abc300_b', priority: 1, comment: '' },
+            { taskId: 'abc301_a', priority: 2, comment: '' },
+          ],
+        }),
+      ];
+      const result = buildTaskIdsFromWorkbooks(workbooks);
+      expect(result).toHaveLength(3);
+      expect(result).toContain('abc300_a');
+      expect(result).toContain('abc300_b');
+      expect(result).toContain('abc301_a');
+    });
+
+    test('returns empty array for empty workbooks', () => {
+      expect(buildTaskIdsFromWorkbooks([])).toEqual([]);
+    });
+
+    test('returns empty array when workbooks have no tasks', () => {
+      const workbooks = [
+        createWorkBookListBase({ id: 1, workBookTasks: [] }),
+        createWorkBookListBase({ id: 2, workBookTasks: [] }),
+      ];
+      expect(buildTaskIdsFromWorkbooks(workbooks)).toEqual([]);
+    });
+  });
+
   describe('calcWorkBookGradeModes', () => {
     test('returns most frequent grade for each workbook', () => {
       const tasksMapByIds: Map<string, Task> = new Map([

src/features/workbooks/utils/workbooks.ts

@@ -71,6 +71,15 @@ export function countReadableWorkbooks(workbooks: WorkbooksList, userId: string)
   }, 0);
 }
 
+// Deduplicates task IDs across workbooks to avoid redundant DB fetches.
+export function buildTaskIdsFromWorkbooks(
+  workbooks: { workBookTasks: WorkBookTaskBase[] }[],
+): string[] {
+  return Array.from(
+    new Set(workbooks.flatMap((workbook) => workbook.workBookTasks.map((task) => task.taskId))),
+  );
+}
+
 /**
  * Calculates the grade modes for a list of workbooks in curriculum based on their tasks.
  *
@@ -82,7 +91,7 @@ export function countReadableWorkbooks(workbooks: WorkbooksList, userId: string)
  */
 export function calcWorkBookGradeModes(
   workbooks: { id: number; workBookTasks: WorkBookTaskBase[] }[],
-  tasksMapByIds: Map<string, Task>,
+  tasksMapByIds: Map<string, Pick<Task, 'grade'>>,
 ): Map<number, TaskGrade> {
   const gradeModes: Map<number, TaskGrade> = new Map();
 

src/routes/workbooks/+page.server.ts

@@ -1,6 +1,7 @@
 import { error, redirect } from '@sveltejs/kit';
 
 import * as taskCrud from '$lib/services/tasks';
+import { buildTaskIdsFromWorkbooks } from '$features/workbooks/utils/workbooks';
 import * as taskResultsCrud from '$lib/services/task_results';
 import * as workBooksCrud from '$features/workbooks/services/workbooks';
 
@@ -60,25 +61,29 @@ export async function load({ locals, url }) {
   const adminUser = loggedInUser && isAdmin(loggedInUser.role as Roles);
 
   try {
-    const [
-      workbooks,
-      availableCategories,
-      solutionCategoryMap,
-      tasksMapByIds,
-      taskResultsByTaskId,
-    ] = await Promise.all([
-      fetchWorkbooksByTab(tab, selectedGrade, selectedCategory, !!adminUser),
-      tab === WorkBookTab.SOLUTION
-        ? getAvailableSolutionCategories(!!adminUser)
-        : Promise.resolve([]),
-      tab === WorkBookTab.SOLUTION && selectedCategory === ALL_SOLUTION_CATEGORIES
-        ? getSolutionCategoryMapByWorkbookId(!!adminUser)
-        : Promise.resolve(new Map<number, SolutionCategory>()),
-      taskCrud.getTasksByTaskId(),
-      loggedInUser
-        ? taskResultsCrud.getTaskResultsOnlyResultExists(loggedInUser.id, true)
-        : Promise.resolve(new Map()),
-    ]);
+    const [workbooks, availableCategories, solutionCategoryMap, taskResultsByTaskId] =
+      await Promise.all([
+        fetchWorkbooksByTab(tab, selectedGrade, selectedCategory, !!adminUser),
+        tab === WorkBookTab.SOLUTION
+          ? getAvailableSolutionCategories(!!adminUser)
+          : Promise.resolve([]),
+        tab === WorkBookTab.SOLUTION && selectedCategory === ALL_SOLUTION_CATEGORIES
+          ? getSolutionCategoryMapByWorkbookId(!!adminUser)
+          : Promise.resolve(new Map<number, SolutionCategory>()),
+        loggedInUser
+          ? taskResultsCrud.getTaskResultsOnlyResultExists(loggedInUser.id, true)
+          : Promise.resolve(new Map()),
+      ]);
+
+    // Grade modes are only displayed on the CURRICULUM tab for logged-in users.
+    // For other tabs / anonymous, the id list is empty and getTasksWithSelectedTaskIds
+    // returns [] without a query (see tasks.ts guard), so tasksMapByIds becomes an empty Map.
+    const referencedTaskIds =
+      tab === WorkBookTab.CURRICULUM && loggedInUser ? buildTaskIdsFromWorkbooks(workbooks) : [];
+    const referencedTasks = await taskCrud.getTasksWithSelectedTaskIds(referencedTaskIds);
+    const tasksMapByIds = new Map(
+      referencedTasks.map((task) => [task.task_id, { grade: task.grade }]),
+    );
 
     return {
       workbooks,

src/routes/workbooks/+page.svelte

@@ -33,7 +33,7 @@
   let loggedInUser = $derived(data.loggedInUser);
   let role = $derived(loggedInUser?.role as Roles);
 
-  const tasksMapByIds = $derived(data.tasksMapByIds as Map<string, Task>);
+  const tasksMapByIds = $derived(data.tasksMapByIds as Map<string, Pick<Task, 'grade'>>);
   let taskResultsByTaskId = $derived(data.taskResultsByTaskId as Map<string, TaskResult>);
 
   const gradeModesEachWorkbook = $derived(calcWorkBookGradeModes(workbooks, tasksMapByIds));