This class does not define an IdClass

A Y :

My for class Class1Item is a reference to an entry in Class1. Hibernate needs me to define an @IdClass. Defining an own Class with the Id of Class1 did not work for me.

Here is the error I am getting:

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'requestMappingHandlerAdapter' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Unsatisfied dependency expressed through method 'requestMappingHandlerAdapter' parameter 1; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mvcConversionService' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'bookItemRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: This class [class de.models.Class1Item] does not define an IdClass

Relevant Classes which are all in the same package:

import javax.persistence.*;
import javax.validation.constraints.NotNull;

import lombok.*;

import java.io.Serializable;
import java.time.LocalDate;
import java.util.List;

@Entity
@Setter
@Getter
@NoArgsConstructor
@IdClass(Class1ItemId.class)
public class Class1Item implements Serializable {

    @Id
    @ManyToOne
    @JoinColumn(name="reference")
    private Class1 class1;

    @NotNull
    @GeneratedValue
    private Long number;

    @Column(name="date_one")
    private LocalDate date1;

    @Column(name="date_x")
    private LocalDate dateX;

    @ManyToOne
    @JoinColumn(name="userReference")
    private User userReference;

    @ManyToMany
    @JoinColumn(name="waitingUsers")
    private List<User> waitingUsers;

    @NotNull
    @Enumerated(EnumType.STRING)
    @Column(name="enumX")
    private EnumX enumX;

}

import javax.persistence.*;
import javax.validation.constraints.NotBlank;

import lombok.*;

import java.io.Serializable;

@Entity
@Setter
@Getter
@NoArgsConstructor
public class Class1 implements Serializable {

    @Id
    @NotBlank
    private String key;

    @NotBlank
    private String name;

    @NotBlank
    private String nameF;

    @NotBlank
    private String nameL;

    private String path;
}

import javax.persistence.*;
import javax.validation.constraints.NotNull;

import lombok.*;

import java.io.Serializable;
import java.util.Set;

@Entity
@Setter
@Getter
@NoArgsConstructor
public class User implements Serializable {

    @Id
    @Column(name="UserID")
    private Long id;

    @NotNull
    @Column(name="email",unique=true)
    private String email;

    @NotNull
    @Column(name="user_firstname")
    private String firstName;

    @NotNull
    @Column(name="user_lastname")
    private String lastName;

    @NotNull
    @Column(name="isAdmin")
    private Boolean isAdmin;

    @ManyToMany
    @Column(name="wantedItems")
    private Set<Class1Item> wantedItems;

    @OneToMany
    @Column(name="borrowedItems")
    private Set<Class1Item> itemsBorrowed;
}

import javax.persistence.Id;
import java.io.Serializable;

public class Class1ItemId implements Serializable {
    @Id
    private String key;
}

How do I fix this error when there's actually an IdClass defined?

Marco Behler :

You have an @IdClass defined, but not the key re-declared in your ClassItem @Entity. They must match.

You need to add them like so:

@Entity
@IdClass(Class1ItemId.class)
// others
public class Class1Item implements Serializable {

    @Id
    private String key; // from your Class1ItemId

  // others

}