@Entity @Data
 public class JoinedNutrionalValueIngredient implements Serializable {
    
        @EmbeddedId
        private NutrionalValueIngredientId id = new NutrionalValueIngredientId();
    
    // ... rest of class  
 }

在JoinedNutrionalValueIngredient类中，复合id NutrionalValueIngredientId应被示例化。

如下所示更改变量Names
长成分ID到长成分ID nutrional_value_id到nutrionalvalueid
例如

@Column(name = "ingredient_id")
  Long ingredient_id;

到

@Column(name = "ingredient_id")
Long ingredientid;

然后为所有字段生成getter setter。Hibernate无法设置字段，因为没有公共getter/setter。

设置id实体“NutrionalValueDientId”的值，然后尝试将其作为“JoinedNutrionalValueDient”的嵌入id插入。参考以下示例：

package com.example;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Embeddable;

@Embeddable
public class EmployeeId implements Serializable
{
private static final long serialVersionUID = 1L;
@Column(name = "EMP_ID")
private int empId;
@Column(name = "DEPARTMENT")
private String department;

public EmployeeId()
{
    super();
}
public EmployeeId(int empId, String department)
{
    super();
    this.empId = empId;
    this.department = department;
}

public int getEmpId()
{
    return empId;
}
public void setEmpId(int empId)
{
    this.empId = empId;
}
public String getDepartment()
{
    return department;
}
public void setDepartment(String department)
{
    this.department = department;
}
@Override
public int hashCode()
{
    final int prime = 31;
    int result = 1;
    result = prime * result + ((department == null) ? 0 : department.hashCode());
    result = prime * result + empId;
    return result;
}
@Override
public boolean equals(Object obj)
{
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    EmployeeId other = (EmployeeId) obj;
    if (department == null)
    {
        if (other.department != null)
            return false;
    } else if (!department.equals(other.department))
        return false;
    if (empId != other.empId)
        return false;
    return true;
}
 }

参考上面的嵌入式ID类（Embedded Id）。这是Employee类的主键。因此，我们需要在ID class中设置值（ID ID）然后，将ID class注入到Employee作为主键。然后它会工作。如果没有主键，则该值为null。

package com.example;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Employee implements Serializable
{
private static final long serialVersionUID = 1L;
@EmbeddedId
EmployeeId id;
@Column(name="EMP_NAME")
private String empName;

public Employee()
{
    super();
}
public Employee(EmployeeId id, String empName)
{
    super();
    this.id = id;
    this.empName = empName;
}
public EmployeeId getId()
{
    return id;
}
public void setId(EmployeeId id)
{
    this.id = id;
}
public String getEmpName()
{
    return empName;
}
public void setEmpName(String empName)
{
    this.empName = empName;
}
}

设置ID类和其他字段的值，如下所示。

//Create a new Employee object   
 Employee employee = new Employee();

 EmployeeId employeeId = new EmployeeId(1,"DailyNews");
 employee.setEmpName("CompositeKey");
 employee.setId(employeeId);

 session.save(employee);

检查您是否正在为嵌入式ID设置示例。我没有得到这个错误。
我改变这个

@EmbeddedId
ProductUserId id;    

ProductUser(Integer productId, Integer UserId, Double rating){
    this.rating = rating
}

到

@EmbeddedId
ProductUserId id;    

ProductUser(Integer productId, Integer userId, Double rating){
    this.id = new ProductUserId(productId, userId);
    this.rating = rating
}

在我的例子中，发生的事情是，我试图持久化一个实体，该实体的组成ID带有一个空字段（因为错误说“为...生成了空ID”）。在你的例子中，我试图持久化一个这样的对象（参见ing）：

JoinedNutrionalValueIngredientId wrongId = new JoinedNutrionalValueIngredientId(null, 435L)
JoinedNutrionalValueIngredient ing = new JoinedNutrionalValueIngredient(wrongId, ...);

在我的例子中，这个错误来自错误的DTO转换。为了解决这个问题，我简单地改变了逻辑，在持久化之前将这个字段设置为它的值。