@OneToMany mapping in spring boot app

Question

I am using spring framework in my product class there is @OneToMany relationship between product and productReview So I mapped this relation as follows but when I called findAll() method of products it gives me an error of Bad String I cant figure out what is the problem , when I removed @OneToMany relation it runs perfectly

Product.java

 @Entity
@Table(name="products")
public class Product implements Serializable{

    private static final long serialVersionUID = 1L;

    @Id
    @SequenceGenerator(name="SEQ_PRODUCTS", sequenceName="PRODUCTS_SEQ", allocationSize=1)
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="SEQ_PRODUCTS")
    private Long id;

    @NotEmpty
    @Column(name="NAME", nullable=false)
    private String name;
    @ManyToMany
    private List<ProductImages> productImages;

    @OneToMany(mappedBy="product",targetEntity=ProductReview.class,fetch = FetchType.EAGER,cascade = CascadeType.ALL)
    private List <ProductReview> productReviews; 
    ..... Getter and setter of above fields 
    }

ProductReview.class

@Entity
public class ProductReview implements Serializable {

    private static final long serialVersionUID = 1L;

    @GeneratedValue(strategy=GenerationType.AUTO)
    @Id
    private Long id;

    private String title;

    private String message;

    private Double rating;

    @ManyToOne
    private Product product;
    ..... Getter and setter
    }

API : http://localhost:8080/api/products

Response : Bad String

@FirzaAhmed you should get exception in console if you need more info. But the main problem here is that you probably get some sort of recursive relations that Jackson cant resolve without additional helper info. So setup annotations or custom serializer. Another option is to remove one part of the relation that you will not use in your program, like there is no point to have List <ProductReview> productReviews, because you can always query ProductReview table if you need this info — varren

Sivakumar Sivakumar · Accepted Answer · 2017-10-31T07:16:19

On your ProductReview entity add @JoinColumn annotation to your Product field

@Entity
public class ProductReview implements Serializable {

....
@ManyToOne
@JoinColumn(name="product_id")
private Product product;
..... Getter and setter
}

@OneToMany mapping in spring boot app

2 Answers