Spring Batch Job not working, Spring stopping execution

Question

I am very new to the spring batch. Trying to create a simple example for myself to understand some of the basic batch-processing concepts. Currently, my spring application starts but unable to execute a simple job which is as follows

Read from the Student.json file
Dump it into the database

Adding the GitHub repo link below the code snippets. Do feel free to suggest any other improvements if you can. Thank you :)

   public ItemReader<Student> jsonItemReader() {
       return new JsonItemReaderBuilder<Student>()
               .jsonObjectReader(new JacksonJsonObjectReader<>(Student.class))
               .resource(new ClassPathResource("Students.json"))
               .name("studentJsonItemReader")
               .saveState(true)
               .build();
   }

    public Step sampleStep(JobRepository jobRepository, PlatformTransactionManager transactionManager) {
        return new StepBuilder("studentProcessor", jobRepository)
                .<Student, Student>chunk(10, transactionManager)
                .reader(jsonItemReader())
                .writer(itemWriter())
                .processor(studentProcessor)
                .build();
    }

@Bean
    public Job sampleJob(JobRepository jobRepository, Step sampleJob) {
        return new JobBuilder("sampleJob", jobRepository)
                .start(sampleJob)
                .build();
    }

@Bean
    public ItemWriter<Student> itemWriter() {
        return new StudentWriter();
    }

public class StudentWriter implements ItemWriter<Student> {

    @Autowired
    private StudentRespository studentRespository;

    @Override
    public void write(Chunk<? extends Student> chunk) throws Exception {
        studentRespository.saveAll(chunk);
    }
}

Github link : https://github.com/mohasink24/spring-batch

score 3 · Accepted Answer · answered Apr 12 '23 at 04:42

I checked your sample. A few things:

You need to remove @EnableBatchProcessing here. With Spring Boot 3, there is no need for that annotation, unless you want to take complete control over how Spring Batch is configured (see migration notes)
The item processor is currently returning new instances of items, not the ones that were read and mapped from actual data by the reader. With that, "empty" items will be written by the writer in the database. This should rather be return student (after some processing, otherwise the processor is useless if it returns exactly the same input item).
The item writer is autowiring a collaborator here, but is not declared as a Spring @Component. You should have a warning from any decent IDE with Spring support on this. Otherwise, you can remove the @Autowired annotation, add a constructor that accepts a StudentRepository and inject the repository when you create the bean:

@Bean
public ItemWriter<Student> itemWriter(StudentRepository studentRepository) {
   return new StudentWriter(studentRepository);
}

Those are already some good starting points to fix before going further. If you still have the issue, please update the question and the code and I will try to follow up on this.

Thank you Mahmoud Ben Hassine. These are really helpful suggestions. — Mohasin Kazi, Apr 12 '23 at 11:53

Spring Batch Job not working, Spring stopping execution

1 Answers1