JPA 查询 - class 错误中没有合适的构造函数

Question

我有一个 Employee 实体 class，它有很多列。我想从这个 class 中获取一些列，因此我使用了 dtos。我创建了一个新的 BaseEmployee class 并在 EmployeeRepository 中编写了查询。但是当我尝试运行 app.

时出现此错误：“class 错误中没有合适的构造函数”

@Entity
@Table(name = "employees")
@Data
@AllArgsConstructor
@NoArgsConstructor
@JsonAutoDetect(fieldVisibility = Visibility.ANY)
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "emp_no")
    private  int id;
    @Column(name = "birth_date")   
    private Date birthDate;
    @Column(name = "first_name")
    private String firstName;
    @Column(name = "last_name")
    private String lastName;
    @Column(name = "gender")
    private char gender;
    @Column(name = "hire_date")  
    private Date hireDate;

    @OneToMany(mappedBy = "employees")
    private List<Title> titles; 

    @OneToMany(mappedBy = "employees")
    private List<Salary> salary;

    @OneToMany(mappedBy = "employee")
    private List<DeptEmp> departmentList;

   @OneToMany(mappedBy = "employee")
   private List<DeptManager> managerDepartment;

}

我的 dto class:

@Data
@NoArgsConstructor
@AllArgsConstructor
public class BaseEmployee {

    private  int id;
    private Date birthDate;
    private String firstName;
    private String lastName;
    private char gender;
    private Date hireDate;

}

Jpa 存储库：

public interface EmployeeRepository extends JpaRepository<Employee,Integer> {
    
    List<Employee> getByFirstNameContains(String firstName);
    List<Employee> getByFirstNameStartsWith(String firstName);


    @Query("Select new dev.serhat.employeeapi.models.dtos.BaseEmployee"
    + "(e.id, e.birthDate, e.firstName, e.lastName, e.gender, e.hireDate) From Employee e WHERE e.id = :id")
    Optional<BaseEmployee> getBaseEmployeeById(int id);
    
    
}

错误：

HH000400: Using dialect: org.hibernate.dialect.MySQL5InnoDBDialect
2022-02-20 16:33:42.533  INFO 24371 --- [  restartedMain] o.h.e.t.j.p.i.JtaPlatformInitiator       : HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
2022-02-20 16:33:42.559  INFO 24371 --- [  restartedMain] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2022-02-20 16:33:43.431 ERROR 24371 --- [  restartedMain] o.h.hql.internal.ast.ErrorTracker        :  Unable to locate appropriate constructor on class [dev.serhat.employeeapi.models.dtos.BaseEmployee]. Expected arguments are: int, java.util.Date, java.lang.String, java.lang.String, char, java.util.Date
[cause=org.hibernate.PropertyNotFoundException: no appropriate constructor in class: dev.serhat.employeeapi.models.dtos.BaseEmployee]
2022-02-20 16:33:43.443 ERROR 24371 --- [  restartedMain] o.h.hql.internal.ast.ErrorTracker        :  Unable to locate appropriate constructor on class [dev.serhat.employeeapi.models.dtos.BaseEmployee]. Expected arguments are: int, java.util.Date, java.lang.String, java.lang.String, char, java.util.Date
[cause=org.hibernate.PropertyNotFoundException: no appropriate constructor in class: dev.serhat.employeeapi.models.dtos.BaseEmployee]

org.hibernate.hql.internal.ast.DetailedSemanticException: Unable to locate appropriate constructor on class [dev.serhat.employeeapi.models.dtos.BaseEmployee]. Expected arguments are: int, java.util.Date, java.lang.String, java.lang.String, char, java.util.Date
        at org.hibernate.hql.internal.ast.tree.ConstructorNode.resolveConstructor(ConstructorNode.java:182) ~[hibernate-core-5.6.4.Final.jar:5.6.4.Final]

Answer 1

错误非常简单，您的 class BaseEmployee 缺少执行 getBaseEmployeeById() 所需的适当构造函数。您的 class 带有 @NoArgsConstructor 和 @AllArgsConstructor 注释，但这些 lombok 注释可能无法被 Spring 识别。您的方法 getBaseEmployeeById() 需要一个具有以下签名的明确定义的构造函数：

public BaseEmployee(int id, Date birthDate, String firstName, String lastName, char gender, Date hireDate)

目前缺少这样的构造函数。

请向您的 class 添加具有所述签名的构造函数，然后重试。

Answer 2

Lombok 生成的 all-args 构造函数调用两个类型为 java.util.Date 的参数。

当 hibernate 执行您的 jpql 时，它在构造函数中使用 org.hibernate.type.TimestampType 个对象，而不是 java.util.Date 个对象。当然没有生成这样的构造函数，因此出现错误。

下面是关于如何处理这种情况的堆栈溢出讨论：How to force Hibernate to return dates as java.util.Date instead of Timestamp?

JPA 查询 - class 错误中没有合适的构造函数

JPA Query - no appropriate constructor in class error

java

hibernate

dto

spring-data-jpa

spring-boot