feat: 코스 수정할 때 권한 확인 Guard 구현 #83

backend/src/course/guards/CoursePermissionGuard.ts

@@ -0,0 +1,20 @@
+import { CanActivate, ExecutionContext, Injectable } from '@nestjs/common';
+import { CourseService } from '../course.service';
+import { CoursePermissionException } from '../exception/CoursePermissionException';
+
+@Injectable()
+export class CoursePermissionGuard implements CanActivate {
+  constructor(private readonly courseService: CourseService) {}
+
+  async canActivate(context: ExecutionContext): Promise<boolean> {
+    const request = context.switchToHttp().getRequest();
+    const courseId = Number(request.params.id);
+    const userId = Number(request.user.userId);
+
+    const course = await this.courseService.getCourseById(courseId);
+    if (course.user.id !== userId) {
+      throw new CoursePermissionException(courseId);
+    }
+    return course.user.id === userId;
+  }
+}