Custom SpringBatch ItemReader, that read form JPA repository using custom query - spring

Question

I am new to Spring Batch and I would like to seek the advice of the experienced programmer on how to implement the following:
I am writing an API that triggers a batch task to generate a report from a list of transactions from JPA repo.
In spring batch, there is ItemReader, ItemProcessor, ItemWriter for each step.
How should I implement my ItemReader such that it can execute the following:
Generate a custom query from the parameters set in the jobParameters (obtained from the API query)
Using the custom query in 2 to obtain the list of transactions from the Transactions JPA repo, which will be processed in the ItemProcessor and subsequently generate reports through ItemWriter.
Question: How should I write the ItemReader, I looking at JpaCursorItemReader (dk if it is the right one) but could not find examples of implementation online to refer to. Any help is appreciated. Thank you.
I am at the stage of trying to understand how Spring batch works, I hope to seek proper guidance from experts in this field of the direction to go to accomplished the mentioned task.

Answer 1

Generate a custom query from the parameters set in the jobParameters (obtained from the API query)
You can define a step-scoped bean and inject job parameters to use them in your query:
#Bean
#StepScope
public JpaCursorItemReader jpaCursorItemReader(#Value("#{jobParameters['parameter']}") String parameter) {
return new JpaCursorItemReaderBuilder()
.queryString("..") // use job parameter in your query here
// set other properties on the item reader
.build();
}
You can find more details on step-scoped components in the documentation here: Late Binding of Job and Step Attributes.