How To Solve com.fasterxml.jackson.databind.ser Error

Question

I am getting databind error. The error occurred after connecting manyToOne and oneToMany. I suspect this.

*Product class contains multiple records belonging to category and supplier (Northwind Database)

Error:

at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.13.4.2.jar:2.13.4.2]
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.13.4.2.jar:2.13.4.2]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:774) ~[jackson-databind-2.13.4.2.jar:2.13.4.2]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.13.4.2.jar:2.13.4.2]
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.13.4.2.jar:2.13.4.2]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:774) ~[jackson-databind-2.13.4.2.jar:2.13.4.2]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.13.4.2.jar:2.13.4.2]

The problem started when I added the connection annotations here:

Product Entity:

package com.JpaTraining.JpaTraining.entities.concretes;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import lombok.Data;

@Entity
@Data
@Table(name = "products")
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "product_id")
    private int productId;
    @Column(name = "product_name")
    private String productName;

    @ManyToOne
    @JoinColumn(name = "supplier_id")
    private Supplier supplier;

    @ManyToOne
    @JoinColumn(name = "category_id")
    private Category category;
    @Column(name = "unit_price")
    private double unitPrice;
    @Column(name = "units_in_stock")
    private int unitsInStock;

    public Product() {
    }

    public Product(int productId, String productName, Supplier supplier, Category category, double unitPrice,
            int unitsInStock) {
        this.productId = productId;
        this.productName = productName;
        this.supplier = supplier;
        this.category = category;
        this.unitPrice = unitPrice;
        this.unitsInStock = unitsInStock;
    }
}

Category Entity:

package com.JpaTraining.JpaTraining.entities.concretes;

import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import lombok.Data;

@Entity
@Data
@Table(name = "categories")
public class Category {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "category_id")
    private int categoryId;
    @Column(name = "category_name")
    private String categoryName;

    @OneToMany(mappedBy = "category")
    private List<Product> product;

    public Category() {
    }

    public Category(int categoryId, String categoryName, List<Product> product) {
        this.categoryId = categoryId;
        this.categoryName = categoryName;
        this.product = product;
    }
}

Supplier Entity:

package com.JpaTraining.JpaTraining.entities.concretes;

import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import lombok.Data;

@Entity
@Data
@Table(name = "suppliers")
public class Supplier {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "supplier_id")
    private int supplierId;
    @Column(name = "company_name")
    private String supplierName;

    @OneToMany(mappedBy = "supplier")
    private List<Product> product;

    public Supplier() {

    }

    public Supplier(int supplierId, String supplierName, List<Product> product) {
        this.supplierId = supplierId;
        this.supplierName = supplierName;
        this.product = product;
    }

}

Charsets:

Answer 1

In the Product and Category classes you can leave out two fields: private Listproduct and try again : link ref link