I am trying to access job parameters in an ItemReader as shown below, but even trying several approaches, I could not find a proper way that is suitable for the lastest Spring Batch version (most of the answers on SO are 8-10 years old).

In order to pass jobParameters to ItemReader, I am using StepExecution as shown below, but as constructor of CustomDataReader is executed before the beforeStep method, I get error on setCollection(collectionName) line. So, how to fix it?

@Component
public class CustomDataReader extends MongoCursorItemReader<Document> {

    private String collectionName;

    @BeforeStep
    public void beforeStep(final StepExecution stepExecution) {
        JobParameters jobParameters = stepExecution.getJobParameters();
        collectionName = jobParameters.getParameter("collectionName").getValue().toString();
    }

    // @Autowired
    public CustomDataReader(
            @Qualifier("mongoTemplate") MongoTemplate mongoTemplate
    ) {
        setName("customDataReader");
        setTargetType(Document.class);
        setTemplate(mongoTemplate);
        setCollection(collectionName);
        setBatchSize(DEFAULT_CHUNK_SIZE);
        setLimit(DEFAULT_LIMIT_SIZE);
        setQuery(query);
    }

}

I also tried to use the following approach with getter-setter, but still the values are null in the constructor of the reader:

@Value("#{jobParameters[collectionName]}")
private String collectionName;

I am looking an elegant solution without using these job parameters in BatchConfig and only modifying this reader.