add filter to course

Backend/src/controllers/CoursesController.ts

@@ -1,4 +1,4 @@
-import { Get, Body, Post, Route, Tags, SuccessResponse, Response, Delete, Controller, Security, Request, Put, Path } from 'tsoa';
+import { Get, Body, Post, Route, Tags, SuccessResponse, Response, Delete, Controller, Security, Request, Put, Path, Query } from 'tsoa';
 import { ValidationError } from '../middleware/errorHandler';
 import { listCourseResponse } from '../types/courses.types';
 import { CoursesService } from '../services/courses.service';
@@ -8,11 +8,16 @@ import { CoursesService } from '../services/courses.service';
 export class CoursesController {
     private coursesService = new CoursesService();
 
+    /**
+     * ดึงรายการคอร์สทั้งหมด (สามารถ filter ด้วย category_id ได้)
+     * Get all courses (can filter by category_id)
+     * @param category_id - รหัสหมวดหมู่ / Category ID (optional)
+     */
     @Get()
     @SuccessResponse('200', 'Courses fetched successfully')
     @Response('401', 'Invalid or expired token')
-    public async listCourses(): Promise<listCourseResponse> {
-        return await this.coursesService.ListCourses();
+    public async listCourses(@Query() category_id?: number): Promise<listCourseResponse> {
+        return await this.coursesService.ListCourses(category_id);
     }
 
     @Get('{id}')

Backend/src/services/courses.service.ts

@@ -6,9 +6,15 @@ import { listCourseResponse, getCourseResponse } from '../types/courses.types';
 import { UnauthorizedError, ValidationError, ForbiddenError } from '../middleware/errorHandler';
 
 export class CoursesService {
-    async ListCourses(): Promise<listCourseResponse> {
+    async ListCourses(category_id?: number): Promise<listCourseResponse> {
         try {
-            const courses = await prisma.course.findMany();
+            const where: Prisma.CourseWhereInput = {};
+
+            if (category_id) {
+                where.category_id = category_id;
+            }
+
+            const courses = await prisma.course.findMany({ where });
             return {
                 code: 200,
                 message: 'Courses fetched successfully',