Spring Batch - Read query from file and execute it on database - spring

Question

I know I can simply read the file straight from step1, a moment before setting the sql query into the reader, but I want to keep the process of reading the query separate from database reading.
Here is my job configuration.
#Configuration
public class BatchConfiguration {
[...]
#Bean
#StepScope
public JdbcCursorItemReader<Map<String, Object>> dynamicSqlItemReader() {
JdbcCursorItemReader<Map<String, Object>> jir = new JdbcCursorItemReader<>();
jir.setSql((String) contextHolder.getContext().get("fileContent"));
jir.setDataSource(dataSource);
jir.setRowMapper(new ColumnMapRowMapper());
return jir;
}
private FlatFileItemReader<String> flatFileItemReader() {
[...]
}
private ItemWriter<? super String> sysoItemWriter() {
return (ItemWriter<String>) list -> {
for (String element : list) {
System.out.println(element);
}
contextHolder.getContext().put("fileContent", list.get(0));
};
}
#Bean
public ItemWriter<Map<String, Object>> customerItemWriter() {
return list -> {
for (Map<String, Object> stringObjectMap : list) {
System.out.println(stringObjectMap);
}
};
}
#Bean
public Step step0() {
return stepBuilderFactory.get("step0")
.<String, String>chunk(1)
.reader(flatFileItemReader())
.writer(sysoItemWriter())
.build();
}
#Bean
public Step step1() {
return stepBuilderFactory.get("step1")
.<Map<String, Object>, Map<String, Object>>chunk(10)
.reader(dynamicSqlItemReader())
.writer(customerItemWriter())
.build();
}
#Bean
public Job job() throws Exception {
return jobBuilderFactory.get("job")
.incrementer(new RunIdIncrementer())
.start(step0())
.next(step1())
.build();
}
}
This throws a java.lang.IllegalArgumentException: The SQL query must be provided because the contextHolder.getContext().get("fileContent") is still null at time of setting the query.

Answer 1

Before step1, you could write a tasklet for building the query and putting it into context, so that it stays separate and also it becomes available to step1. See more about tasklet here: Tasklet to delete a table in spring batch

Answer 2

You are not using your created contextHolder properly that's why the value there is null.
Make sure you are putting your data in flatFileItemReader() in contextHolder in directly as a map because when you are getting value, you are using contextholder.getContext(). Since it's an simple map,not a ApplicationContext, the method you are using does not exist.