[Chapter 8] 좋아요 구현하기

### 65. 좋아요 구현-Likes 모델 만들기

1. 좋아요 모델 만들기

story.js

```java
<button>
	 <i class="fas fa-heart active" id="storyLikeIcon-${image.id}" onclick="toggleLike(${image.id})"></i>
</button>

let likeIcon = $(`#storyLikeIcon-${imageId}`);
```

com.cos.photogramstart.domain.likes.Likes.java

```java
package com.cos.photogramstart.domain.likes;

import java.time.LocalDateTime;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.PrePersist;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;

import com.cos.photogramstart.domain.image.Image;
import com.cos.photogramstart.domain.subscribe.Subscribe;
import com.cos.photogramstart.domain.user.User;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

@Builder
@Entity // DB에 테이블을 생성
@Data
@NoArgsConstructor // 빈 생성자
@AllArgsConstructor // 전체 생성자
@Table(
	uniqueConstraints = {
			@UniqueConstraint(
					name="likes_uk",
					columnNames = {"imageId","userId"}
					
					)
	}
) // 유니크
public class Likes { // N

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY) // 번호 증가 전략이 데이터베이스를 따라간다.
	private int id;
	
	@JoinColumn(name="imageId")
	@ManyToOne
	private Image image; // 1
	
	// 오류가 터지고 나서 잡아봅시다.
	@JoinColumn(name="userId")
	@ManyToOne
	private User user; // 1
	
	private LocalDateTime createDate;
	
	@PrePersist // DB에 Insert가 되기 직전에 실행
	public void createDate() {
		this.createDate = LocalDateTime.now();
	}
}
```

### 66. 좋아요 구현-좋아요 및 좋아요취소 API 구현하기

1. 좋아요 API 만들기

LikesRepository.java

```java
package com.cos.photogramstart.domain.likes;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;

public interface LikesRepository extends JpaRepository<Likes, Integer>{

	@Modifying
	@Query(value="INSERT INTO likes(imageId, userId, createDate) VALUES(:imageId, :principalId, now()", nativeQuery = true)
	int mLikes(int imageId, int principalId);
	
	@Modifying
	@Query(value="DELETE FROM likes WHERE imageId = :imageId AND userId = :principalId", nativeQuery = true)
	int mUnLikes(int imageId, int principalId);
	
}
```

LikesService.java

```java
package com.cos.photogramstart.service;

import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.cos.photogramstart.domain.likes.LikesRepository;

import lombok.RequiredArgsConstructor;

@Service
@RequiredArgsConstructor
public class LikesService {
	
	private final LikesRepository likesRepository;
	
	@Transactional
	public void 좋아요(int imageId, int principalId) {
		likesRepository.mLikes(imageId, principalId);
	}
	
	@Transactional
	public void 좋아요취소(int imageId, int principalId) {
		likesRepository.mUnLikes(imageId, principalId);
	}
}
```

ImageApiController.java

```java
package com.cos.photogramstart.web.api;

import java.util.List;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.data.web.PageableDefault;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.security.core.annotation.AuthenticationPrincipal;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import com.cos.photogramstart.config.auth.PrincipalDatails;
import com.cos.photogramstart.domain.image.Image;
import com.cos.photogramstart.service.ImageService;
import com.cos.photogramstart.service.LikesService;
import com.cos.photogramstart.web.dto.CMRespDto;

import lombok.RequiredArgsConstructor;

@RequiredArgsConstructor
@RestController
public class ImageApiController {

	private final ImageService imageService;
	private final LikesService likesService;
	
	@GetMapping("/api/image")
	public ResponseEntity<?> imageStory(@AuthenticationPrincipal PrincipalDatails principalDatails,
			@PageableDefault(size=3) Pageable pageable){
		Page<Image> images = imageService.이미지스토리(principalDatails.getUser().getId(), pageable);
		return new ResponseEntity<>(new CMRespDto<>(1, "성공",images),HttpStatus.OK); // JS에서 호출해야함
	}
	
	@PostMapping("/api/image/{imageId}/likes")
	public ResponseEntity<?> likes(@PathVariable int imageId, @AuthenticationPrincipal PrincipalDatails principalDatails){
		likesService.좋아요(imageId,principalDatails.getUser().getId());
		return new ResponseEntity<>(new CMRespDto<>(1,"좋아요성공",null),HttpStatus.CREATED);
	}
	
	@DeleteMapping("/api/image/{imageId}/likes")
	public ResponseEntity<?> unlikes(@PathVariable int imageId, @AuthenticationPrincipal PrincipalDatails principalDatails){
		likesService.좋아요취소(imageId,principalDatails.getUser().getId());
		return new ResponseEntity<>(new CMRespDto<>(1,"좋아요취소성공",null),HttpStatus.OK);
	}
	
}
```

### 67. 좋아요 구현-좋아요 뷰 렌더링

1. 좋아요 구현하기

ImageService.java

```java
private final ImageRepository imageRepository;
	
	@Transactional(readOnly = true) // 영속성 컨텍스트 변경 감지를 해서, 더티체킹, flush(반영) X
	public Page<Image> 이미지스토리(int principalId,Pageable pageable) {
		Page<Image> images = imageRepository.mStory(principalId, pageable);
		
		// 2(cos) 로그인 
		// images에 좋아요 상태 담기
		images.forEach((image)->{
			image.getLikes().forEach((like)->{
				if(like.getUser().getId() == principalId) { // 해당 이미지에 좋아요한 사람들을 찾아서 현재 로그인한 사람이 좋아요 한것인지 비교
					image.setLikeState(true);
				}
			});
		});
		
		
		return images;
	}
```

story.js

```java
<div class="sl__item__contents">
		<div class="sl__item__contents__icon">

			<button>`;
				if(image.likeState) {
					item += `<i class="fas fa-heart active" id="storyLikeIcon-${image.id}" onclick="toggleLike(${image.id})"></i>`;
				}else{
					item += `<i class="fas fa-heart" id="storyLikeIcon-${image.id}" onclick="toggleLike(${image.id})"></i>`;
				}
				
			
			item += `
			</button>
		</div>
```

### 68. 좋아요 구현-좋아요 카운트 뷰 렌더링

Image.java

```java
@Transient
	private int likeCount;
```

story.js

```java
<span class="like"><b id="storyLikeCount-${image.id}">${image.likeCount}</b>likes</span>
```

### 69. 좋아요 구현-좋아요 구현 완료

ImageService.java

```java
private final ImageRepository imageRepository;
	
	@Transactional(readOnly = true) // 영속성 컨텍스트 변경 감지를 해서, 더티체킹, flush(반영) X
	public Page<Image> 이미지스토리(int principalId,Pageable pageable) {
		Page<Image> images = imageRepository.mStory(principalId, pageable);
		
		// 2(cos) 로그인 
		// images에 좋아요 상태 담기
		images.forEach((image)->{
			
			image.setLikeCount(image.getLikes().size());
			
			image.getLikes().forEach((like)->{
				if(like.getUser().getId() == principalId) { // 해당 이미지에 좋아요한 사람들을 찾아서 현재 로그인한 사람이 좋아요 한것인지 비교
					image.setLikeState(true);
				}
			});
		});
		
		
		return images;
	}
```

story.js

```java
// (3) 좋아요, 안좋아요
function toggleLike(imageId) {
	let likeIcon = $(`#storyLikeIcon-${imageId}`);
	
	if (likeIcon.hasClass("far")) { // 좋아요 하겠다
		
		$.ajax({
			type:"post",
			url:`/api/image/${imageId}/likes`,
			dataType:"json"
		}).done(res=>{
			
			let likeCountStr = $(`#storyLikeCount-${imageId}`).text();
			let likeCount = Number(likeCountStr)+1;
			$(`#storyLikeCount-${imageId}`).text(likeCount);
			
			likeIcon.addClass("fas");
			likeIcon.addClass("active");
			likeIcon.removeClass("far");
		}).fail(error=>{
			console.log("오류",error);
		});
		

	} else { 						// 좋아요 취소 하겠다.
	
		$.ajax({
			type:"delete",
			url:`/api/image/${imageId}/likes`,
			dataType:"json"
		}).done(res=>{
			
			let likeCountStr = $(`#storyLikeCount-${imageId}`).text();
			let likeCount = Number(likeCountStr)-1;
			$(`#storyLikeCount-${imageId}`).text(likeCount);
			
			likeIcon.removeClass("fas");
			likeIcon.removeClass("active");
			likeIcon.addClass("far");
		}).fail(error=>{
			console.log("오류",error);
		});
	}
}
```

### 70. 좋아요 구현-무한참조 버그 잡기

Likes.java

```java
// 오류가 터지고 나서 잡아봅시다.
	@JsonIgnoreProperties({"images"})
	@JoinColumn(name="userId")
	@ManyToOne
	private User user; // 1
```