最近在写一个cmdb系统的分页，尽管Django本身有分页的模块儿，但是还是想实现一下自己心中想的分页的一种逻辑
因为，在我们工作当中，当我们的数据量超级大的时候，其实我们每次分页查询都不必将所有的数据查询出来，而是可以按阶段的查询，举个例子
每次查询5页数据，当需要第六页的时候，再次进行加载,为了更加明了，做了举例
首先我们规定好每次查询5页，每页4条数据
1 db_data = list(range(1,100)) 2 3 final_page = len(db_data) 4 5 one_page_num = 5 #每页4条 6 one_time_num = 5 #每次查5页
1、查询索引的逻辑 设定findIndex查询的索引
1 # page = 1 int(1/5) + 1 findIndex = 1 2 # page = 2 int(2/5) + 1 findIndex = 1 3 # page = 3 int(3/5) + 1 findIndex = 1 4 # page = 4 int(4/5) + 1 findIndex = 1 5 # page = 5 int(5/5) findIndex = 1 6 # page = 6 int(6/5) + 1 findIndex = 2 7 # page = 7 int(7/5) + 1 findIndex = 2 8 # page = 8 int(8/5) + 1 findIndex = 2 9 # page = 9 int(9/5) + 1 findIndex = 2 10 # page = 10 int(10/5) findIndex = 2 11 # page = 11 int(11/5) + 1 findIndex = 3 12 # page = 12 int(12/5) + 1 findIndex = 3 13 # page = 13 int(13/5) + 1 findIndex = 3 14 # page = 14 int(14/5) + 1 findIndex = 3 15 # page = 15 int(15/5) findIndex = 3
所以我们可以写如下代码
1 if page/one_time_num > int(page/one_time_num): 2 findIndex = int(page / one_time_num) + 1 3 else: 4 findIndex = int(page / one_time_num) 5 #进行第一次查询，查询每次5页，每页4条的数据 6 select_num = one_time_num * one_page_num #这里决一次定查询20条 7 select_start = (findIndex - 1) * select_num # 开始查询的索引 8 select_down = findIndex * select_num # 结束查询的索引 9 select_data = db_data[select_start: select_down] #这里查询出了一次20条数据
这个时候是查询出20条数据了，但是，我们想要的具体的数据和页码对不上，所以做了以下的数据
1 #下面对20条数据进行截取 2 #findIndex 1 3 # page = 1 1-(0*5) gnPage = 1 4 # page = 2 2-(0*5) gnPage = 2 5 # page = 3 3-(0*5) gnPage = 3 6 # page = 4 4-(0*5) gnPage = 4 7 # page = 5 5-(0*5) gnPage = 5 8 #findIndex 2 9 # page = 6 6-(1*5) gnPage = 1 10 # page = 7 7-(1*5) gnPage = 2 11 # page = 8 8-(1*5) gnPage = 3 12 # page = 9 9-(1*5) gnPage = 4 13 # page = 10 10-(1*5) gnPage = 5 14 #findIndex 3 15 # page = 11 11-(2*5) gnPage = 1 16 # page = 12 12-(2*5) gnPage = 2 17 # page = 13 13-(2*5) gnPage = 3 18 # page = 14 14-(2*5) gnPage = 4 19 # page = 15 15-(2*5) gnPage = 5
所以我们可以得到以下代码来获取具体的一页数据
#设定 截取的索引位now_index now_index = page - (findIndex-1)*one_time_num #设定单页的截取起始 page_start = (now_index - 1) * one_page_num page_end = now_index * one_page_num #开始截取 page_data = select_data[page_start:page_end]
最后进行代码结合
1 #coding:utf-8 2 3 db_data = list(range(1,100)) 4 5 one_page_num = 5 #每页4条 6 one_time_num = 5 #每次查5页 7 8 9 while True: 10 page = int(input("page >>>")) #输入页码 11 12 #查询索引的逻辑 设定findIndex查询的索引 13 # page = 1 int(1/5) + 1 findIndex = 1 14 # page = 2 int(2/5) + 1 findIndex = 1 15 # page = 3 int(3/5) + 1 findIndex = 1 16 # page = 4 int(4/5) + 1 findIndex = 1 17 # page = 5 int(5/5) findIndex = 1 18 # page = 6 int(6/5) + 1 findIndex = 2 19 # page = 7 int(7/5) + 1 findIndex = 2 20 # page = 8 int(8/5) + 1 findIndex = 2 21 # page = 9 int(9/5) + 1 findIndex = 2 22 # page = 10 int(10/5) findIndex = 2 23 # page = 11 int(11/5) + 1 findIndex = 3 24 # page = 12 int(12/5) + 1 findIndex = 3 25 # page = 13 int(13/5) + 1 findIndex = 3 26 # page = 14 int(14/5) + 1 findIndex = 3 27 # page = 15 int(15/5) findIndex = 3 28 29 if page/one_time_num > int(page/one_time_num): 30 findIndex = int(page / one_time_num) + 1 31 else: 32 findIndex = int(page / one_time_num) 33 #进行第一次查询，查询每次5页，每页4条的数据 34 select_num = one_time_num * one_page_num #这里决一次定查询20条 35 select_start = (findIndex - 1) * select_num # 开始查询的索引 36 select_down = findIndex * select_num # 结束查询的索引 37 38 select_data = db_data[select_start: select_down] #这里查询出了一次20条数据 39 40 #下面对20条数据进行截取 41 #findIndex 1 42 # page = 1 1-(0*5) gnPage = 1 43 # page = 2 2-(0*5) gnPage = 2 44 # page = 3 3-(0*5) gnPage = 3 45 # page = 4 4-(0*5) gnPage = 4 46 # page = 5 5-(0*5) gnPage = 5 47 #findIndex 2 48 # page = 6 6-(1*5) gnPage = 1 49 # page = 7 7-(1*5) gnPage = 2 50 # page = 8 8-(1*5) gnPage = 3 51 # page = 9 9-(1*5) gnPage = 4 52 # page = 10 10-(1*5) gnPage = 5 53 #findIndex 3 54 # page = 11 11-(2*5) gnPage = 1 55 # page = 12 12-(2*5) gnPage = 2 56 # page = 13 13-(2*5) gnPage = 3 57 # page = 14 14-(2*5) gnPage = 4 58 # page = 15 15-(2*5) gnPage = 5 59 #设定 截取的索引位now_index 60 now_index = page - (findIndex-1)*one_time_num 61 #设定单页的截取起始 62 page_start = (now_index - 1) * one_page_num 63 page_end = now_index * one_page_num 64 #开始截取 65 page_data = select_data[page_start:page_end] 66 #输出效果 67 print("+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++") 68 print("当前是第%s次查询"%findIndex) 69 print("当前查询到的所有数据是 %s" % select_data) 70 print("当前是 %s 页" % page) 71 print("当前的数据是 %s " % page_data) 72 print("+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++")
大家试一下吧。