Spring boot not recognize my Jpa repository Not a managed type: class java.lang.Long

Question

I'm creating a simple spring boot application using spring data jpa and lombok but when I added my repository class based on JPARepository and started my application I get an error of creating my repository class this the exception:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'projetRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class java.lang.Long
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1702) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:579) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:741) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at com.errabi.glsid.SurveyBuilderApplication.main(SurveyBuilderApplication.java:14) [classes/:na]
Caused by: java.lang.IllegalArgumentException: Not a managed type: class java.lang.Long
    at org.hibernate.metamodel.internal.MetamodelImpl.managedType(MetamodelImpl.java:472) ~[hibernate-core-5.2.16.Final.jar:5.2.16.Final]
    at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.<init>(JpaMetamodelEntityInformation.java:73) ~[spring-data-jpa-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.jpa.repository.support.JpaEntityInformationSupport.getEntityInformation(JpaEntityInformationSupport.java:66) ~[spring-data-jpa-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getEntityInformation(JpaRepositoryFactory.java:181) ~[spring-data-jpa-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:119) ~[spring-data-jpa-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:102) ~[spring-data-jpa-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:298) ~[spring-data-commons-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.lambda$afterPropertiesSet$3(RepositoryFactoryBeanSupport.java:287) ~[spring-data-commons-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.util.Lazy.getNullable(Lazy.java:141) ~[spring-data-commons-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.util.Lazy.get(Lazy.java:63) ~[spring-data-commons-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:290) ~[spring-data-commons-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:102) ~[spring-data-jpa-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1761) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1698) ~[spring-beans-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    ... 16 common frames omitted

My entity:

package com.errabi.glsid.entities;

import java.util.Date;
import java.util.List;

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

import lombok.Data;

@Data
@Entity
public class Projet {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long codeProjet ;
    private String description;
    private String responsable ;
    private Double budget ;
    private Date dateDebut;
    private Date dateFin ;
    @OneToMany(mappedBy="codeQuestonnaire")
    private List<Questionnaire> questionnaires ;
     
}

This is my repository class:

@Repository
public interface ProjetRepository extends JpaRepository<Long, Projet> {

    /*@Query("select p from Projet p")
    public List<Projet> findAllProjets();*/
}

And this is my configuration class:

package com.errabi.glsid;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@SpringBootApplication
@EntityScan("com.errabi.glsid.entities")
@EnableJpaRepositories(basePackages = {"com.errabi.glsid.repositories"})
public class TestApplication {

    public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    }
}

Answer 1

Alternately, you should not use @Data on JPA entities because it generates equals and hashCode, and toString as well on every fields including relation fields like your list.

Specify @EqualsAndHashCode and @ToString on your identity field.

Answer 2

The position of these generic arguments inside JpaRepository are inverted. The code should be like this:

@Repository
public interface ProjetRepository extends JpaRepository<Projet, Long> {

    /*@Query("select p from Projet p")
    public List<Projet> findAllProjets();*/
}