Question

我创建RestController来检索使用JPQL的可分页实体子级。一切正常，直到我将大小作为参数。

这是我的老师课：

@Entity
public class Teacher {
    @Id
    private String id;
    private String name;
    protected Teacher () {}
    public String getId() {
        return id; }

    @ManyToMany
    @JoinTable(name = "Teacher_Room", joinColumns = @JoinColumn(name = "Teacher_Id"), 
    inverseJoinColumns = @JoinColumn(name = "Room_Id"))
    List<Room> Rooms = new ArrayList<>();

    public void setId(String id) {
        this.id = id;}

    public String getName() {
        return name;}

    public void setName(String name) {
        this.name = name;}

    public List<Room> getRooms() {
        return Rooms;}

    public void setRooms(List<Room> rooms) {
        Rooms = rooms;}
}

房间等级：

@Entity(name="Room")
public class Room {
    @Id
    private String id;  
    private String name;

    protected Room() {  }

    public String getName() {
        return name;}

    public String getId() {
        return id;}

    public void setId(String id) {
        this.id = id;}

    public void setName(String name) {
        this.name = name;}
}

教师资料库：

@Repository
interface TeacherRepository extends JpaRepository<Teacher, String> {
    @Query(value = "SELECT t.Rooms FROM Teacher t where t.id = :id")
    public Page<Room> findRooms(String id,  Pageable pageable);
}

老师RestController：

@RestController
public class TeacherController {

    @Autowired
    private TeacherRepository teacherRepository;

    @GetMapping("/{id}/rooms")
    public Page<Room> getRooms(Pageable pageable, @PathVariable String id) {

        Page<Room> pageRooms = teacherRepository.findRooms(id,pageable);

        return pageRooms;
    }
}

结果：http://localhost:8080/teacher/01/rooms给我正确的结果。

{
    "content": [
        {
            "id": "A",
            "name": "Class-A"
        },
        {
            "id": "B",
            "name": "Class-B"
        },
        {
            "id": "C",
            "name": "Class-C"
        },
        {
            "id": "D",
            "name": "Class-D"
        },
        {
            "id": "E",
            "name": "Class-E"
        },
        {
            "id": "F",
            "name": "Class-F"
        }
    ],
    "pageable": {
        "sort": {
            "sorted": false,
            "unsorted": true,
            "empty": true
        },
        "offset": 0,
        "pageNumber": 0,
        "pageSize": 20,
        "paged": true,
        "unpaged": false
    },
    "last": true,
    "totalElements": 6,
    "totalPages": 1,
    "size": 20,
    "number": 0,
    "sort": {
        "sorted": false,
        "unsorted": true,
        "empty": true
    },
    "numberOfElements": 6,
    "first": true,
    "empty": false
}

但是如果出现以下错误，请告诉我：http://localhost:8080/teacher/01/rooms?size=3

{
    "timestamp": "2019-02-28T19:00:52.796+0000",
    "status": 500,
    "error": "Internal Server Error",
    "message": "could not prepare statement; SQL [select count(.) as col_0_0_ from teacher teacher0_
     cross join teacher_room rooms1_, room room2_ where teacher0_.id=rooms1_.teacher_id 
     and rooms1_.room_id=room2_.id and teacher0_.id=?]; nested exception is
     org.hibernate.exception.SQLGrammarException: could not prepare statement",
    "path": "/01/rooms"
}

我需要建议，谢谢Jigu

使用JPQL检索可分页实体子级

0 个答案: