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Spring Boot + Thymeleaf + LombokでException evaluating SpringEL expression

Last updated at 2023-03-20Posted at 2023-03-17

Spring徹底入門のチュートリアルをアレンジを加えながら進めていたところ、画面表示時にエラーとなったため、検証してみました。

環境

windowds 11
Java 17
Spring Boot 3.0.4
Spring 6.0.6
Thymleaf 3.1.1
STS 4

ソース抜粋

作成したソースは以下の通りです。
Spring徹底入門のチュートリアルではSpring Data JPAを使っていますが、MyBatisを使うようにしました。

RoomsController.java

@Controller
@RequestMapping("rooms")
public class RoomsController {
    @Autowired
    RoomService roomService;

    @RequestMapping(method = RequestMethod.GET)
    String listRooms(Model model) {
        LocalDate today = LocalDate.now();
        List<AvailableReservableRoom> rooms = roomService.findReservableRooms(today);
        model.addAttribute("date", today);
        model.addAttribute("rooms", rooms);
        return "room/listRooms";
    }
}

RoomService.java

@Service
@Transactional
public class RoomService {
    @Autowired
    AvailableReservableRoomMapper reservableRoomMapper;

    public List<AvailableReservableRoom> findReservableRooms(LocalDate date) {
        return reservableRoomMapper.finbByReservedDate(date);
    }
}

AvailableReservableRoomMapper.java

@Mapper
public interface AvailableReservableRoomMapper {
    List<AvailableReservableRoom> finbByReservedDate(LocalDate reservedDate);
}

AvailableReservableRoom.java

import lombok.Data;

@Data
public class AvailableReservableRoom {
    private Integer roomId;
    private LocalDate reservedDate;
    private String roomName;
}

AvailableReservableRoomMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="mrs.domain.mapper.AvailableReservableRoomMapper">
    <resultMap id="availableReservableRoomMap"
        type="mrs.domain.model.AvailableReservableRoom">
        <result column="room_id" jdbcType="INTEGER" property="roomId" />
        <result column="reserved_date" jdbcType="DATE" property="reservedDate" />
        <result column="room_name" jdbcType="VARCHAR" property="roomName" />
    </resultMap>
    <select id="finbByReservedDate" parameterType="java.time.LocalDate" resultMap="availableReservableRoomMap">
        select
            t1.reserved_date,
            t1.room_id,
            t2.room_name
        from
            reservable_room t1,
            meeting_room t2
        <where>
                t1.room_id = t2.room_id
            and t1.reserved_date = #{reservedDate}
        </where>
        order by room_id
    </select>
</mapper>

listRooms.html

<ul>
    <li th:each="room: ${rooms}">
        <a th:href="@{'/reservations/' + ${date} + '/' + ${room.roomId}}"
           th:text="${room.roomName}"></a>
    </li>
</ul>

画面表示

Spring Bootを起動し、http://localhost:8080/rooms にアクセスすると以下のエラーとなりました。

検証

STSのコンソールを確認したところ、htmlに表示する際にフィールドが見つからない旨のエラーとなっている模様です。

エラーログ

org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "room.roomId" (template: "room/listRooms" - line 15, col 12)
	at org.thymeleaf.spring6.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:292) ~[thymeleaf-spring6-3.1.1.RELEASE.jar:3.1.1.RELEASE]
	at org.thymeleaf.standard.expression.VariableExpression.executeVariableExpression(VariableExpression.java:166) ~[thymeleaf-3.1.1.RELEASE.jar:3.1.1.RELEASE]
	at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:66) ~[thymeleaf-3.1.1.RELEASE.jar:3.1.1.RELEASE]
～
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1008E: Property or field 'roomId' cannot be found on object of type 'mrs.domain.model.AvailableReservableRoom' - maybe not public or not valid?
	at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:217) ~[spring-expression-6.0.6.jar:6.0.6]
	at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:104) ~[spring-expression-6.0.6.jar:6.0.6]
	at org.springframework.expression.spel.ast.PropertyOrFieldReference$AccessorLValue.getValue(PropertyOrFieldReference.java:405) ~[spring-expression-6.0.6.jar:6.0.6]

Controllerで確認すると値は設定されているように見えます。