Spring 引导中的 JPA 查询不返回任何结果

Question

我使用 H2 数据库和一些 JPA 查询创建了一个非常小而简单的 Spring Boot 应用程序。

我的控制器如下：

package me.abhishek.springboot.microservice.example.todo.springbootmicroservicetodoservice;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class ThingsToDoController {
    @Autowired
    ThingsToDoRepository repository;
    @GetMapping("/")
    public String index() {
        return "Hello from the ToDo Controllern";
    }
    @GetMapping("/todo/{name}")
    public ThingsToDo getThingsToDo(@PathVariable String name) {
        ThingsToDo thingToDo=repository.findByNameIgnoreCaseContaining(name);
        return thingToDo;
    }
}

我的豆子如下：

package me.abhishek.springboot.microservice.example.todo.springbootmicroservicetodoservice;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="things_to_do")
public class ThingsToDo {
    @Id
    private Long id;
    @Column(name="name")
    private String name;
    @Column(name="verified")
    private int verificationStatus;
    private String task;
    public ThingsToDo() {
    }
    public ThingsToDo(Long id, String name, int verificationStatus, String task) {
        super();
        this.id=id;
        this.name=name;
        this.verificationStatus=verificationStatus;
        this.task=task;
    }
    public Long getId() {
        return id;
    }
    public String getName() {
        return name;
    }
    public int getVerificationStatus() {
        return verificationStatus;
    }
    public String getTask() {
        return task;
    }
    @Override
    public String toString() {
        return "ThingsToDo{" + 
                "id=" + id + 
                ", name='" + name + ''' +
                ", verificationStatus='" + verificationStatus + ''' +
                '}';
    }
}

H2 数据库架构为：

create table things_to_do
(
    id int,
    name varchar(500),
    verified boolean
);

我运行以将值插入数据库的查询是：

insert into things_to_do (id, name, verified) values (1, 'Hello', 1);
insert into things_to_do (id, name, verified) values (2, 'Bye', 0);

但是，当我执行 get to http://localhost:8080/todo/Hello 时，它不会向我返回任何值;而如果我只是 ping http://localhost:8080，它确实会输出Hello from the ToDo Controller。 有人可以指出我错过了什么步骤吗？ 谢谢！

编辑：从日志中(不过我不太了解(：

select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)
Hibernate: select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)
Hibernate: select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)
Hibernate: select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)
Hibernate: select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)
Hibernate: select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)
Hibernate: select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)
Hibernate: select thingstodo0_.id as id1_0_, thingstodo0_.name as name2_0_, thingstodo0_.task as task3_0_, thingstodo0_.verified as verified4_0_ from things_to_do thingstodo0_ where upper(thingstodo0_.name) like upper(?)

编辑：

ThingsToDoRepository如下：

package me.abhishek.springboot.microservice.example.todo.springbootmicroservicetodoservice;
import org.springframework.data.jpa.repository.JpaRepository;
public interface ThingsToDoRepository extends JpaRepository<ThingsToDo, Long> {
    ThingsToDo findByNameIgnoreCaseContaining(String name);
}

Answer 1

尝试将属性spring.jpa.hibernate.ddl-auto设置为application.properties文件中的update：

spring.jpa.hibernate.ddl-auto=update

由于H2是一个嵌入式数据库，因此 Spring 会自动将默认值 spring.jpa.hibernate.ddl-auto 设置为 create-drop ，这会覆盖您的schema.sql和data.sql。

Spring 引导会根据以下条件为您选择一个默认值 它是否认为您的数据库是嵌入式的。它默认为 如果未检测到架构管理器或全部未检测到架构管理器，则创建-删除 其他情况。

参考

此外，您应该在ThingsToDoRepository类的顶部添加@Repository。