JPA使用之@Query的常用写法

Posted 2020-12-13 mrcharleshu

准备

实体

@Data
@Table(name = "task_apply")
@Entity
public class TaskApply {
    @Id
    @GeneratedValue
    @Column(name = "apply_id")
    private Long applyId;
    
    private Integer status;
    
    private SyncType type;
    
    @Column(name = "task_message")
    private String taskMessage;
}

其中同步类型

package com.charles.enums

public enum SyncType {
    /**
     * 手动同步
     */
    MANUAL("M", "手动同步"),
    /**
     * 任务同步
     */
    SCHEDULED("S", "任务同步");

    private final String value;
    private final String text;

    SyncType(String value, String text) {
        this.value = value;
        this.text = text;
    }

    public String text() {
        return text;
    }

    public String getValue() {
        return value;
    }

    public static SyncType fromValue(String type) {
        for (SyncType value : SyncType.values()) {
            if (value.equals(type)) {
                return value;
            }
        }
        return null;
    }
}

枚举的转换器

import javax.persistence.AttributeConverter;

public class SyncTypeConverter implements AttributeConverter<SyncType, String> {

    @Override
    public String convertToDatabaseColumn(SyncType e) {
        if (e == null) {
            return null;
        }
        return e.getValue();
    }

    @Override
    public SyncType convertToEntityAttribute(String value) {
        if (value == null) {
            return null;
        }
        return SyncType.fromValue(value);
    }
}

修改

使用冒号传参

@Modifying
@Query("update TaskApply set status = :status where applyId = :applyId")
void updateStatusByApplyId(@Param("applyId") Long applyId, @Param("status") Integer status);

使用问号传参

@Modifying
@Query("update TaskApply set status = ?2 where applyId = ?1")
void updateStatusByApplyId(Long applyId, Integer status);

查询

返回指定列第1种写法

package com.charles.vo;

@Data
public class TaskMessageVO {
    private Long applyId;
    private String taskMessage;
}

@Query("select new com.charles.vo.TaskMessageVO(applyId, taskMessage) from TaskApply where applyId in (:applyIds)")
List<TaskMessageVO> findTaskMessages(@Param("applyIds") List<Long> applyIds);

返回指定列第2种写法

@Query(nativeQuery = true, value = 
"SELECT id as applyId, task_message as taskMessage FROM task_apply WHERE apply_id IN (:applyIds)")
List<Object> findTaskMessages(@Param("applyIds") List<Long> applyIds);

这种写法是nativeQuery，返回的结果中每个Object中返回的是一个数组，数组下标0对应的是applyId，下标1对应的是taskMessage。

查询单列

@Query("select distinct status from TaskApply where applyId in (:applyIds)")
List<Integer> findDistinctStatus(@Param("applyIds") List<Long> applyIds);

查询条件为常量

@Query("select applyId from TaskApply where type <> com.charles.enums.SyncType.MANUAL")
List<Long> findNotManualSyncApplyIds();

参考

• spel-support-in-spring-data-jpa-query-definitions
• Spring Data JPA @Query
• Spring JPA selecting specific columns
• spring-data-jpa-query-with-parameter-properties
• Spring @Query annotation with enum parameter
• Can I use enum parameter into JpaRepository nativeQuery?
• Spring Expression Language (SpEL)
• Using Literals in JPQL
• Persisting Enums in JPA