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@QueryProjection

- 상품 조회시 DTO 객체로 결곽밧을 받는 방법

- Item 객체로 값을 받은 후 DTO 클래스로 변환하는 과정 없이 바로 DTO객체를 뽑아낼수 있다.

 

1) DTO 생성

package com.shop.dto;

import com.querydsl.core.annotations.QueryProjection;
import lombok.Getter;
import lombok.Setter;

@Getter
@Setter
public class MainItemDto {
    private Long id;
    private String itemNm;
    private String itemDetail;
    private String imgUrl;
    private Integer price;

    @QueryProjection
    public MainItemDto(Long id, String itemNm, String itemDetail, String imgUrl, Integer price){
        this.id = id;
        this.itemNm = itemNm;
        this.itemDetail = itemDetail;
        this.imgUrl = imgUrl;
        this.price = price;
    }
}

 

2) 컴파일

 

3) 인터페이스 메소드 생성

package com.shop.repository;

import com.shop.dto.ItemSearchDto;
import com.shop.dto.MainItemDto;
import com.shop.entity.Item;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;

public interface ItemRepositoryCustom {
    ...

    Page<MainItemDto> getMainItemPage(ItemSearchDto itemSearchDto, Pageable pageable);
}

 

4) 인터페이스 구현

- selectForm 에서 select 로 변경되었고 select() 메소드안에 매개변수 형태도 달라졌다.

package com.shop.repository;

import com.querydsl.core.QueryResults;
import com.querydsl.core.types.dsl.BooleanExpression;
import com.querydsl.jpa.impl.JPAQuery;
import com.querydsl.jpa.impl.JPAQueryFactory;
import com.shop.constant.ItemSellStatus;
import com.shop.dto.ItemSearchDto;
import com.shop.dto.MainItemDto;
import com.shop.dto.QMainItemDto;
import com.shop.entity.Item;
import com.shop.entity.ItemImg;
import com.shop.entity.QItem;
import com.shop.entity.QItemImg;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.Pageable;
import org.springframework.data.support.PageableExecutionUtils;
import org.thymeleaf.util.StringUtils;

import javax.persistence.EntityManager;
import java.time.LocalDateTime;
import java.util.List;

public class ItemRepositoryCustomImpl implements ItemRepositoryCustom{
    private JPAQueryFactory queryFactory;

    ...

    public BooleanExpression itemNmLike(String searchQuery){
        return StringUtils.isEmpty(searchQuery) ? null : QItem.item.itemNm.like("%"+searchQuery+"%");
    }

    @Override
    public Page<MainItemDto> getMainItemPage(ItemSearchDto itemSearchDto, Pageable pageable) {
        QItem item = QItem.item;
        QItemImg itemImg = QItemImg.itemImg;

        List<MainItemDto> fetch = queryFactory
                .select(new QMainItemDto(
                        item.id,
                        item.itemNm,
                        item.itemDetail,
                        itemImg.imgUrl,
                        item.price
                ))
                .from(itemImg)
                .join(itemImg.item, item)
                .where(itemImg.repimgYn.eq("Y"))
                .where(itemNmLike(itemSearchDto.getSearchQuery()))
                .orderBy(item.id.desc())
                .offset(pageable.getOffset())
                .limit(pageable.getPageSize())
                .fetch();

        JPAQuery<MainItemDto> count = queryFactory
                .select(new QMainItemDto(
                        item.id,
                        item.itemNm,
                        item.itemDetail,
                        itemImg.imgUrl,
                        item.price
                ))
                .from(itemImg)
                .join(itemImg.item, item)
                .where(itemImg.repimgYn.eq("Y"))
                .where(itemNmLike(itemSearchDto.getSearchQuery()));

        return PageableExecutionUtils.getPage(fetch, pageable, ()-> count.fetch().size());
    }
}

 

5) 서비스 구현

package com.shop.service;

import com.shop.dto.ItemFormDto;
import com.shop.dto.ItemImgDto;
import com.shop.dto.ItemSearchDto;
import com.shop.dto.MainItemDto;
import com.shop.entity.Item;
import com.shop.entity.ItemImg;
import com.shop.repository.ItemImgRepository;
import com.shop.repository.ItemRepository;
import lombok.RequiredArgsConstructor;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.multipart.MultipartFile;

import javax.persistence.EntityNotFoundException;
import java.util.ArrayList;
import java.util.List;

@Service
@Transactional
@RequiredArgsConstructor
public class ItemService {

    private final ItemRepository itemRepository;
    private final ItemImgService itemImgService;
    private final ItemImgRepository itemImgRepository;

    ...

    @Transactional(readOnly = true)
    public Page<MainItemDto> getMainItemPgae(ItemSearchDto itemSearchDto, Pageable pageable){
        return itemRepository.getMainItemPage(itemSearchDto, pageable);
    }
}

 

6) 컨트롤러 작성

package com.shop.controller;

import com.shop.dto.ItemSearchDto;
import com.shop.dto.MainItemDto;
import com.shop.service.ItemService;
import lombok.RequiredArgsConstructor;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

import java.util.Optional;

@Controller
@RequiredArgsConstructor
public class MainController {

    private final ItemService itemService;

    @GetMapping(value = "/")
    public String main(ItemSearchDto itemSearchDto, Optional<Integer> page, Model model){
        Pageable pageable = PageRequest.of(page.isPresent() ? page.get() : 0, 6);
        Page<MainItemDto> items = itemService.getMainItemPgae(itemSearchDto, pageable);
        model.addAttribute("items", items);
        model.addAttribute("itemSearchDto", itemSearchDto);
        model.addAttribute("maxPage", 5);
        return "main";
    }
}

 

7) main.html 작성

소스길어서 아래링크 참고

https://github.com/gusrl6394/SpringbootShop/blob/master/src/main/resources/templates/main.html

 

결과)