java - Spring batch FlatFileItemWriter write as csv from Object

Question

I am using Spring batch and have an ItemWriter as follows:

public class MyItemWriter implements ItemWriter<Fixing> {

    private final FlatFileItemWriter<Fixing> writer;
    private final FileSystemResource resource;

    public MyItemWriter () {
        this.writer = new FlatFileItemWriter<>();
        this.resource = new FileSystemResource("target/output-teste.txt");
    }


    @Override
    public void write(List<? extends Fixing> items) throws Exception {

        this.writer.setResource(new FileSystemResource(resource.getFile()));
        this.writer.setLineAggregator(new PassThroughLineAggregator<>());
        this.writer.afterPropertiesSet();
        this.writer.open(new ExecutionContext());
        this.writer.write(items);
    }

    @AfterWrite
    private void close() {
        this.writer.close();
    }
}

When I run my spring batch job, the items are written to file as:

Fixing{id='123456', source='TEST', startDate=null, endDate=null}
Fixing{id='1234567', source='TEST', startDate=null, endDate=null}
Fixing{id='1234568', source='TEST', startDate=null, endDate=null}

1/ How can I write just the data so that the values are comma separated and where it is null, it is not written. So the target file should look like this:

123456,TEST
1234567,TEST
1234568,TEST

2/ Secondly, I am having an issue where only when I exit spring boot application, I am able to see the file get created. What I would like is once it has processed all the items and written, the file to be available without closing the spring boot application.

Answer 1

Since you are using PassThroughLineAggregator which does item.toString() for writing the object, overriding the toString() function of classes extending Fixing.java should fix it.