I Am Facing "java.lang.IllegalArgumentException: Can not set int field com.example.demo.model.Customer.customerId to java.util.LinkedHashMap"

Question

I am getting:

java.lang.IllegalArgumentException: Can not set int field com.example.demo.model.Customer.customerId to java.util.LinkedHashMap

in my Spring Boot Project in which I am trying to persist data of two Pojo classes using Hibernate One-To-Many Relationship. I am trying to save values of a persistent class that has a Collection element Set defined.

The Parent Pojo Class:-

package com.example.demo.model;

import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name = "vendor")
public class Vendor {

    @Id
    int vendorId;

    @Column
    String vendorName;

    @OneToMany(fetch = FetchType.LAZY, targetEntity = Customer.class, cascade = CascadeType.ALL)
    @JoinColumn(name = "vendorId")

    Set children;

    public int getVendorId() {
        return vendorId;
    }

    public void setVendorId(int vendorId) {
        this.vendorId = vendorId;
    }

    public String getVendorName() {
        return vendorName;
    }

    public void setVendorName(String vendorName) {
        this.vendorName = vendorName;
    }

    public Set getChildren() {
        return children;
    }

    public void setChildren(Set children) {
        this.children = children;
    }
}

Child Pojo Class:-

package com.example.demo.model;

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

import org.hibernate.annotations.GeneratorType;

import com.fasterxml.jackson.databind.annotation.JsonDeserialize;

@Entity
@Table(name = "customer")
public class Customer {

    @Id
    int customerId;

    @Column
    String customerName;

    public int getCustomerId() {
        return customerId;
    }

    public void setCustomerId(int customerId) {
        this.customerId = customerId;
    }

    public String getCustomerName() {
        return customerName;
    }

    public void setCustomerName(String customerName) {
        this.customerName = customerName;
    }

}

Controller Class:-

package com.example.demo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import com.example.demo.model.Vendor;
import com.example.demo.service.VendorDataSaveService;

@RestController
public class VendorSaveController {

    @Autowired
    private VendorDataSaveService dataSaveService;

    @PostMapping("/save")
    public void saveVendor(@RequestBody Vendor vendor) {
        dataSaveService.saveVendorRecord(vendor);
    }
}

Service Class:-

package com.example.demo.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.example.demo.model.Vendor;
import com.example.demo.repository.VendorDataSaveRepository;

@Service
public class VendorDataSaveService {

    @Autowired
    private VendorDataSaveRepository repository;

    public void saveVendorRecord(Vendor vendor) {
        repository.save(vendor);
    }
}

Repository Class:-

package com.example.demo.repository;

import org.springframework.data.jpa.repository.JpaRepository;

import com.example.demo.model.Vendor;

public interface VendorDataSaveRepository extends JpaRepository<Vendor, Integer> {

}

The JSON Format which I am sending from Postman:-

{
    "vendorId" : 101,
    "vendorName" : "JAIN BOOKS",
    "children" : [{
                    "customerId" : 1,
                    "customerName" : "AMIT"
                 }]
}

Error Message From Console:-

java.lang.IllegalArgumentException: Can not set int field com.example.demo.model.Customer.customerId to java.util.LinkedHashMap

Error Message On Postman:-

Error accessing field [int com.example.demo.model.Customer.customerId] by reflection for persistent property [com.example.demo.model.Customer#customerId] : {customerId=1, customerName=AMIT}; nested exception is org.hibernate.property.access.spi.PropertyAccessException: Error accessing field [int com.example.demo.model.Customer.customerId] by reflection for persistent property [com.example.demo.model.Customer#customerId] : {customerId=1, customerName=AMIT}"

Answer 1

Need To add Generic type Customer argument in Set children Collection type.

Set<Customer> children;