fix: validate and handle duplicate application

src/modules/jobs/jobs.service.ts

@@ -46,13 +46,22 @@ export class JobsService {
 
     const { applicant_name, ...others } = jobApplicationDto;
 
+    const existingApplication = await this.jobApplicationRepository.findOne({
+      where: { job: { id: jobId }, applicant_name: jobApplicationDto.applicant_name },
+      relations: ['job'],
+    });
+
+    if (existingApplication) {
+      throw new CustomHttpException('Duplicate application', HttpStatus.BAD_REQUEST);
+    }
+
     const resumeUrl = await this.s3Service.uploadFile(resume, 'resumes');
 
     const createJobApplication = this.jobApplicationRepository.create({
       ...others,
       applicant_name,
       resume: resumeUrl,
-      ...job,
+      job: job.data
     });
 
     await this.jobApplicationRepository.save(createJobApplication);

src/modules/jobs/tests/jobs.service.spec.ts

@@ -224,6 +224,20 @@ describe('JobsService', () => {
       expect(service['jobApplicationRepository'].create).toHaveBeenCalled();
       expect(service['jobApplicationRepository'].save).toHaveBeenCalled();
     });
+
+    it('should throw error if duplicate application is found', async () => {
+      const resume = { buffer: Buffer.from('test file'), originalname: 'resume.pdf' } as Express.Multer.File;
+
+      jest.spyOn(service, 'getJob').mockResolvedValue(mockJob as any);
+      jest
+        .spyOn(service['jobApplicationRepository'], 'findOne')
+        .mockResolvedValue({ ...mockJobApplicationDto, resumeUrl: 'https://s3-bucket-url/resume.pdf' } as any);
+
+      await expect(service.applyForJob('jobId', mockJobApplicationDto, resume)).rejects.toThrow(
+        new CustomHttpException('Duplicate application', HttpStatus.CONFLICT)
+      );
+    });
+
   });
 
   describe('searchJobs', () => {