Module Update

src/modules/questions/data-access.ts

@@ -0,0 +1,93 @@
+import 'server-only';
+
+import { db } from "@/shared/db";
+import { questions, questionsToKnowledgePoints } from "@/shared/db/schema";
+import { and, eq, inArray, count, desc, sql } from "drizzle-orm";
+import { cache } from "react";
+
+// Types for filters
+export type GetQuestionsParams = {
+  page?: number;
+  pageSize?: number;
+  knowledgePointId?: string;
+  difficulty?: number;
+};
+
+// Cached Data Access Function
+// Using React's cache() to deduplicate requests if called multiple times in one render pass
+export const getQuestions = cache(async ({
+  page = 1,
+  pageSize = 10,
+  knowledgePointId,
+  difficulty,
+}: GetQuestionsParams = {}) => {
+  const offset = (page - 1) * pageSize;
+
+  // Build Where Conditions
+  const conditions = [];
+
+  if (difficulty) {
+    conditions.push(eq(questions.difficulty, difficulty));
+  }
+
+  // Filter by Knowledge Point (using subquery pattern for Many-to-Many)
+  if (knowledgePointId) {
+    const subQuery = db
+      .select({ questionId: questionsToKnowledgePoints.questionId })
+      .from(questionsToKnowledgePoints)
+      .where(eq(questionsToKnowledgePoints.knowledgePointId, knowledgePointId));
+    
+    conditions.push(inArray(questions.id, subQuery));
+  }
+
+  // Only fetch top-level questions (parent questions)
+  // Assuming we only want to list "root" questions, not sub-questions
+  conditions.push(sql`${questions.parentId} IS NULL`);
+
+  const whereClause = conditions.length > 0 ? and(...conditions) : undefined;
+
+  // 1. Get Total Count (for Pagination)
+  // Optimization: separate count query is often faster than fetching all data
+  const [totalResult] = await db
+    .select({ count: count() })
+    .from(questions)
+    .where(whereClause);
+  
+  const total = totalResult?.count ?? 0;
+
+  // 2. Get Data with Relations
+  const data = await db.query.questions.findMany({
+    where: whereClause,
+    limit: pageSize,
+    offset: offset,
+    orderBy: [desc(questions.createdAt)],
+    with: {
+      // Preload Knowledge Points
+      questionsToKnowledgePoints: {
+        with: {
+          knowledgePoint: true,
+        },
+      },
+      // Preload Author
+      author: {
+        columns: {
+          id: true,
+          name: true,
+          image: true,
+        },
+      },
+      // Preload Child Questions (first level)
+      children: true, 
+    },
+  });
+
+  return {
+    data,
+    meta: {
+      page,
+      pageSize,
+      total,
+      totalPages: Math.ceil(total / pageSize),
+    },
+  };
+});