feat: enable file upload support for announcement creation with multipart form data handling.

Backend/src/services/announcements.service.ts

@@ -110,17 +110,18 @@ export class AnnouncementsService {
     }
 
     /**
-     * สร้างประกาศใหม่
-     * Create a new announcement
+     * สร้างประกาศใหม่ (พร้อมอัปโหลดไฟล์แนบ)
+     * Create a new announcement with optional file attachments
      */
     async createAnnouncement(input: CreateAnnouncementInput): Promise<CreateAnnouncementResponse> {
         try {
-            const { token, course_id, title, content, status, is_pinned } = input;
+            const { token, course_id, title, content, status, is_pinned, files } = input;
             const decoded = jwt.verify(token, config.jwt.secret) as { id: number };
 
             // Validate instructor access
             await CoursesInstructorService.validateCourseInstructor(token, course_id);
 
+            // Create announcement
             const announcement = await prisma.announcement.create({
                 data: {
                     course_id,
@@ -131,11 +132,52 @@ export class AnnouncementsService {
                     published_at: status === 'PUBLISHED' ? new Date() : null,
                     created_by: decoded.id,
                 },
-                include: {
-                    attachments: true,
-                },
             });
 
+            // Upload attachments if provided
+            const attachments: {
+                id: number;
+                announcement_id: number;
+                file_name: string;
+                file_path: string;
+                created_at: Date;
+                updated_at: Date;
+            }[] = [];
+
+            if (files && files.length > 0) {
+                for (const file of files) {
+                    const timestamp = Date.now();
+                    const uniqueId = Math.random().toString(36).substring(2, 15);
+                    const fileName = file.originalname || 'file';
+                    const extension = fileName.split('.').pop() || '';
+                    const safeFilename = `${timestamp}-${uniqueId}.${extension}`;
+                    const filePath = `courses/${course_id}/announcements/${announcement.id}/${safeFilename}`;
+
+                    // Upload to MinIO
+                    await uploadFile(filePath, file.buffer, file.mimetype || 'application/octet-stream');
+
+                    // Create attachment record
+                    const attachment = await prisma.announcementAttachment.create({
+                        data: {
+                            announcement_id: announcement.id,
+                            file_name: fileName,
+                            file_path: filePath,
+                            file_size: file.size,
+                            mime_type: file.mimetype || 'application/octet-stream',
+                        },
+                    });
+
+                    attachments.push({
+                        id: attachment.id,
+                        announcement_id: attachment.announcement_id,
+                        file_name: attachment.file_name,
+                        file_path: attachment.file_path,
+                        created_at: attachment.created_at,
+                        updated_at: attachment.created_at,
+                    });
+                }
+            }
+
             return {
                 code: 201,
                 message: 'Announcement created successfully',
@@ -147,7 +189,7 @@ export class AnnouncementsService {
                     is_pinned: announcement.is_pinned,
                     created_at: announcement.created_at,
                     updated_at: announcement.updated_at,
-                    attachments: [],
+                    attachments,
                 },
             };
         } catch (error) {