通读策略

小咪咪 2022-12-09 02:40 89阅读 0赞

## 一：通读策略的流程图： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center]

## 二：查询省级信息，加缓存和没有加缓存代码比较： ##

1：没有加缓存

class ProvinceAreasView(View):
        def get(self, request):
    
            try:
                p_data = Area.objects.filter(parent__isnull=True)
            except Exception as e:
                return JsonResponse({
        
                    "code": 400,
                    "errmsg": "查询数据库报错"
                })
            p_list = []
            for p in p_data:
                p_list.append({
        
                    "id": p.id,
                    "name": p.name,
                })
            return JsonResponse({
        
                "code": 0,
                "errmsg": "ok",
                "province_list": p_list
            })

2：增加缓存：  
首先确定我要将什么数据写入缓存----p\_list,

class ProvinceAreasView(View):
        def get(self, request):
    
    
            # 1:首先读缓存
            p_list = cache.get('p_list')
    
            if not p_list:
                # 2:读不到读数据库
                try:
                    p_data = Area.objects.filter(parent__isnull=True)
                except Exception as e:
                    return JsonResponse({
        
                        "code": 400,
                        "errmsg": "查询数据库报错"
                    })
    
    	        p_list = []
    	        for p in p_data:
    	            p_list.append({
        
    	                "id": p.id,
    	                "name": p.name,
    	            })
    	        # 3:回填到缓存中
    	        cache.set("p_list", p_list, 3600)
    	
            return JsonResponse({
        
                "code": 0,
                "errmsg": "ok",
                "province_list": p_list
            })

3:测试：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 1]  
三： 市区信息的缓存配置：  
1：没有加缓存：

class SubAreasView(View):
    
        def get(self, request, pk):
    
            try:
                # 查询父级的对象
                parent_model = Area.objects.get(pk=pk)
    
                # 查询子级的对象
                sub_model_list = Area.objects.filter(parent_id= pk)
            except Exception as e:
                return JsonResponse({
        
                    "code": 200,
                    "errmsg": "查询数据库报错"
                })
    
            sub_list = []
            for sub_model in sub_model_list:
                sub_list.append({
        
                    "id": sub_model.id,
                    "name": sub_model.name,
                })
    
            # 构造响应数据：
            sub_data = {
        
                "id": parent_model.id,
                "name": parent_model.name,
                "subs": sub_list,
            }
    
            return JsonResponse({
        
                "code": 0,
                "errmsg": 200,
                "sub_data": sub_data
            })

2：加缓存之后：

class SubAreasView(View):
    
        def get(self, request, pk):
    
            parent_model = Area.objects.get(pk=pk)
            # 1： 读缓存
            sub_data = cache.get("sub_data_%d"% parent_model.id)
    
            if not sub_data:
    
                try:
                    # 查询子级的对象
                    sub_model_list = Area.objects.filter(parent_id= pk)
                except Exception as e:
                    return JsonResponse({
        
                        "code": 200,
                        "errmsg": "查询数据库报错"
                    })
    
                sub_list = []
                for sub_model in sub_model_list:
                    sub_list.append({
        
                        "id": sub_model.id,
                        "name": sub_model.name,
                    })
                # 2:写缓存
                sub_data = {
        
                "id": parent_model.id,
                "name": parent_model.name,
                "subs": sub_list}
                # 3:回填缓存
                cache.set("sub_data_%s"% parent_model.id, sub_data, 3600)
    
            # 构造响应数据：
            return JsonResponse({
        
                "code": 0,
                "errmsg": 200,
                "sub_data": sub_data
            })

3：测试：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 2]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/39a9db9a3f63450099bc5fc69d581a1d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/5757e82221fc40bd8d4865fee36cd9e4.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221123/6fa6df489a684396990f60962f75def4.png