Spring batch JdbcCursorItemReader : reading from tables having FK relation - spring-batch

Question

Here's my Reader :
private static final String SELECT_ALL_BOOKS = "SELECT * FROM BOOKS WHERE COLOR = 'yellow'";
#Bean
public JdbcCursorItemReader<BookEntity> itemReader(final DataSource dataSource) {
return new JdbcCursorItemReaderBuilder<BookEntity>()
.name("book_reader")
.sql(SELECT_ALL_BOOKS)
.dataSource(dataSource)
.rowMapper(new BeanPropertyRowMapper<>(BookEntity.class))
.build();
}
And my entity :
#Entity
#Getter
#Setter
#Table(name = "book")
#AllArgsConstructor
#NoArgsConstructor
public class BookEntity implements java.io.Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_book")
private Integer idBook;
#Column(name = "color")
private String color;
#Column(name = "page_number")
private Integer pageNumber;
#Column(name = "read")
private Boolean read;
#ManyToOne(fetch = FetchType.EAGER, cascade = {CascadeType.ALL})
#JoinColumn(name = "id_author")
private Author author;
...
...
}
Problem is : with my job executing my step, I'm having the books but with an author = null. So the foreign key is not mapped correctly, all the other String/Integer/Boolean fields are retrieved correctly.
I'm new with Spring batch so maybe I'm using a wrong kind of reader.
Any one has an idea about the problem ? Thanks

Answer 1

Please refer this- You are using JDBC Item reader that is mapped to native columns and properties are binded by BeanPropertyRowMapper
https://docs.spring.io/spring-batch/docs/current/reference/html/readersAndWriters.html#JdbcCursorItemReader
Change the query join with AUTHOR tables as a native query or use JPA readers to support ORM
Below reference will give repository reader
https://docs.spring.io/spring-batch/docs/current/api/org/springframework/batch/item/data/RepositoryItemReader.html
Below example give some idea to implement and its SO references
https://github.com/gpassini/Spring-Batch-RepositoryItemReader-NativeQuery-Example/tree/master/src/main