from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.contrib.auth.models import User

# Create your models here.


# 用于記錄點(diǎn)贊數(shù)量的模型
class LikeCount(models.Model):
 content_type = models.ForeignKey(ContentType, on_delete=models.DO_NOTHING)
 object_id = models.PositiveIntegerField()
 content_object = GenericForeignKey('content_type', 'object_id')
 # 用于記錄點(diǎn)贊數(shù)量的字段
 like_num = models.IntegerField(default=0)


# 用于記錄點(diǎn)贊狀態(tài)的模型
class LikeRecord(models.Model):
 content_type=models.ForeignKey(ContentType, on_delete=models.DO_NOTHING)
 object_id=models.PositiveIntegerField()
 content_object=GenericForeignKey('content_type', 'object_id')
 # 記錄點(diǎn)贊的用戶
 like_user = models.ForeignKey(User, on_delete=models.DO_NOTHING)
 # 記錄點(diǎn)贊的時(shí)間
 like_time = models.DateTimeField(auto_now_add=True)

from django.shortcuts import render, HttpResponseRedirect
from django.contrib.contenttypes.models import ContentType
from django.http import JsonResponse
from .models import LikeCount, LikeRecord

# Create your views here.


# 數(shù)據(jù)操作成功返回?cái)?shù)據(jù)方法
def success_response(like_num):
 data = {}
 data['status'] = 'SUCCESS'
 data['like_num'] = like_num
 return JsonResponse(data)


# 數(shù)據(jù)操作失敗返回信息的方法
def error_response(message):
 data = {}
 data['status'] = 'ERROR'
 data['message'] = message
 return JsonResponse(data)


def like_up(request):
 # 得到GET中的數(shù)據(jù)以及當(dāng)前用戶
 user = request.user
 # 判斷用戶是否登錄
 if not user.is_authenticated:
  return error_response('未登錄，不能進(jìn)行點(diǎn)贊操作')
 content_type = request.GET.get('content_type')
 content_type = ContentType.objects.get(model=content_type)
 object_id = request.GET.get('object_id')
 is_like = request.GET.get('is_like')

 # 創(chuàng)建一個(gè)點(diǎn)贊記錄
 if is_like == 'true':
  # 進(jìn)行點(diǎn)贊，即實(shí)例化一個(gè)點(diǎn)贊記錄
  like_record, created = LikeRecord.objects.get_or_create(content_type=content_type, object_id=object_id, like_user=user)
  # 通過(guò)created來(lái)判斷點(diǎn)贊記錄是否存在，如果存在則不進(jìn)行點(diǎn)贊，如果不存在則進(jìn)行點(diǎn)贊數(shù)量加一
  if created:
   # 不存在點(diǎn)贊記錄并且已經(jīng)創(chuàng)建點(diǎn)贊記錄，需要將點(diǎn)贊數(shù)量加一
   like_count, created = LikeCount.objects.get_or_create(content_type=content_type, object_id=object_id)
   like_count.like_num += 1
   like_count.save()
   return success_response(like_count.like_num)
  else:
   # 已經(jīng)進(jìn)行過(guò)點(diǎn)贊
   return error_response('已經(jīng)點(diǎn)贊過(guò)')
 else:
  # 取消點(diǎn)贊
  # 先查詢數(shù)據(jù)是否存在，存在則進(jìn)行取消點(diǎn)贊
  if LikeRecord.objects.filter(content_type=content_type, object_id=object_id, like_user=user).exists():
   # 數(shù)據(jù)存在，取消點(diǎn)贊
   # 刪除點(diǎn)贊記錄
   LikeRecord.objects.get(content_type=content_type, object_id=object_id, like_user=user).delete()
   # 判斷對(duì)應(yīng)的點(diǎn)贊數(shù)量數(shù)據(jù)是否存在，如果存在則對(duì)點(diǎn)贊數(shù)量進(jìn)行減一
   like_count, create = LikeCount.objects.get_or_create(content_type=content_type, object_id=object_id)
   if create:
    # 數(shù)據(jù)不存在，返回錯(cuò)誤信息
    return error_response('數(shù)據(jù)不存在，不能取消點(diǎn)贊')
   else:
    # 數(shù)據(jù)存在，對(duì)數(shù)量進(jìn)行減一
    like_count.like_num -= 1
    like_count.save()
    return success_response(like_count.like_num)
  else:
   # 數(shù)據(jù)不存在，不能取消點(diǎn)贊
   return error_response('數(shù)據(jù)不存在，不能取消點(diǎn)贊')

<script type="text/javascript">
 function change_like(obj, content_type, object_id) {
  // 判斷obj中是否包含active的元素，用于判斷當(dāng)前狀態(tài)是否為激活狀態(tài)
  var is_like = obj.getElementsByClassName('active').length == 0
  $.ajax({
   url: '/like_up/',
   // 為了避免加入csrf_token令牌，所以使用GET請(qǐng)求
   type: 'GET',
   // 返回的數(shù)據(jù)用于創(chuàng)建一個(gè)點(diǎn)贊記錄
   data: {
    content_type: content_type,
    object_id: object_id,
    is_like: is_like,
   },
   cache: false,
   success: function (data) {
    console.log(data);
    if (data['status'] == 'SUCCESS'){
     // 更新點(diǎn)贊狀態(tài)
     // 通過(guò)class找到對(duì)應(yīng)的標(biāo)簽
     var record = $(obj.getElementsByClassName('glyphicon'))
     if (is_like){
      record.addClass('active')
     }
     else {
      record.removeClass('active')
     }
     // 更新點(diǎn)贊數(shù)量
     var like_num = $(obj.getElementsByClassName('like_num'))
     like_num.text('（' + data['like_num'] + '）')

    }
    else {
     // 以彈窗的形式顯示錯(cuò)誤信息
     alert(data['message'])
    }
   },
   error: function (xhr) {
    console.log(xhr)
   }
  });
  return false;
 };
</script>