13.Django基础之django分页

一、Django的内置分页器(paginator)

view

from django.shortcuts import render,HttpResponse

# Create your views here.
from app01.models import *
from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger

def index(request):

    '''
    批量导入数据:

    Booklist=[]
    for i in range(100):
        Booklist.append(Book(title="book"+str(i),price=30+i*i))
    Book.objects.bulk_create(Booklist)
    '''

    '''
分页器的使用:

    book_list=Book.objects.all()

    paginator = Paginator(book_list, 10)

    print("count:",paginator.count)           #数据总数
    print("num_pages",paginator.num_pages)    #总页数
    print("page_range",paginator.page_range)  #页码的列表



    page1=paginator.page(1) #第1页的page对象
    for i in page1:         #遍历第1页的所有数据对象
        print(i)

    print(page1.object_list) #第1页的所有数据


    page2=paginator.page(2)

    print(page2.has_next())            #是否有下一页
    print(page2.next_page_number())    #下一页的页码
    print(page2.has_previous())        #是否有上一页
    print(page2.previous_page_number()) #上一页的页码



    # 抛错
    #page=paginator.page(12)   # error:EmptyPage 超过页码范围

    #page=paginator.page("z")   # error:PageNotAnInteger 非法页码值
  
    #page = page_obj.page(-1)  #That page number is less than 1 ,也是EmptyPage的错误,页码不能为负数,最少也是1
    '''


    book_list=Book.objects.all()

    paginator = Paginator(book_list, 10) #按照每页显示10条来计算
    page = request.GET.get('page',1)  #将来访问的url是这样的 http://127.0.0.1:8000/路径/?page=1
    currentPage=int(page)


    try:
        print(page)
        book_list = paginator.page(page)
    except PageNotAnInteger:
        book_list = paginator.page(1)
    except EmptyPage:
        book_list = paginator.page(paginator.num_pages)


    return render(request,"index.html",{"book_list":book_list,"paginator":paginator,"currentPage":currentPage})

index.html:




    
    Title
    



分页器

    {% for book in book_list %}
  • {{ book.title }} -----{{ book.price }}
  • {% endfor %}

扩展

from django.core.paginator import Paginator,PageNotAnInteger,EmptyPage
def show(request):

    book_objs = models.Book.objects.all()
    page_obj = Paginator(book_objs,1)
    print('数据总数',page_obj.count)
    print('总页数',page_obj.num_pages)
    print('页码列表',page_obj.page_range)

    page1 = page_obj.page(1)
    for i in page1:
        print(i)
    print(page1.object_list)
    page2 = page_obj.page(2)

    print(page2.has_previous())
    print(page2.has_next())
    print(page2.next_page_number())
    print(page2.previous_page_number())
    # page = page_obj.page(-1)
    page_num = request.GET.get('page',1)

    try:
        current_page_num = int(page_num)
        page_num_data = page_obj.page(current_page_num)
    except PageNotAnInteger:
        current_page_num = 1
        page_num_data = page_obj.page(current_page_num)
    except EmptyPage:
        current_page_num = page_obj.num_pages
        page_num_data = page_obj.page(current_page_num)
    except Exception:
        current_page_num = 1
        page_num_data = page_obj.page(current_page_num)
    if page_obj.num_pages > 11:  #扩展,如果总的页码数大于了11,我们就不把所有的页码数显示出来了,只显示其中11个页面,当前页左边5个,右边5个
        if current_page_num - 5 < 1:  
            pageRange = range(1,12)
        elif current_page_num + 5 > page_obj.num_pages:
            pageRange = range(page_obj.num_pages-10,page_obj.num_pages+1)
        else:
            pageRange = range(current_page_num - 5,current_page_num + 6)

    else:
        pageRange = page_obj.page_range

    book_objs = page_num_data
    return render(request,'show.html',{'book_objs':book_objs,'current_page_num':current_page_num,'page_obj':page_obj,'pageRange':pageRange})

  show.html

{% load static %}



    
    Title
    



数据展示

{% for book_obj in book_objs %} {% endfor %}
id title 价格 性别 出版日期 出版社 作者 操作
{{ book_obj.pk }} {{ book_obj.title }} {{ book_obj.price }} {{ book_obj.get_sex_display }} {{ book_obj.publishDate|date:'Y-d-m' }} {{ book_obj.publish.name }} {% for author in book_obj.authors.all %} {{ author.name }} {% endfor %} 编辑 删除

  model.py文件内容:

from django.db import models

# Create your models here.


class Author(models.Model):
    nid = models.AutoField(primary_key=True)
    name=models.CharField( max_length=32)
    age=models.IntegerField()
    authorDetail=models.OneToOneField(to="AuthorDetail",to_field="nid")
    def __str__(self):
        return self.name
class AuthorDetail(models.Model):

    nid = models.AutoField(primary_key=True)
    birthday=models.DateField()
    telephone=models.BigIntegerField()
    addr=models.CharField( max_length=64)

class Publish(models.Model):
    nid = models.AutoField(primary_key=True)
    name=models.CharField( max_length=32)
    city=models.CharField( max_length=32)
    email=models.EmailField()
    def __str__(self):
        return self.name

class Book(models.Model):

    nid = models.AutoField(primary_key=True)
    title = models.CharField( max_length=32)

    publishDate=models.DateField()
    price=models.DecimalField(max_digits=5,decimal_places=2)
    publish=models.ForeignKey(to="Publish",to_field="nid")
    authors=models.ManyToManyField(to='Author',)
    def __str__(self):
        return self.title

二、自定义分页

  当数据库中数据有很多,我们通常会在前端页面做分页展示。

  分页的数据可以在前端页面实现,也可以在后端实现分页。

  后端实现分页的原理就是每次只请求一页数据。

  准备工作

  我们使用脚本批量创建一些测试数据(将下面的代码保存到bulk_create.py文件中放到Django项目的根目录,直接执行即可。):

import os

if __name__ == "__main__":
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "about_orm.settings")

    import django
    django.setup()

    from app01 import models
    bulk_obj = (models.Publisher(name='第{}出版社'.format(i)) for i in range(300))
    models.Publisher.objects.bulk_create(bulk_obj) #批量添加,注意写法

  看下面几个版本的分页:

def publisher_list(request):
    # 从URL中取当前访问的页码数
    try:
        current_page = int(request.GET.get('page'))
    except Exception as e:
        # 取不到或者页码数不是数字都默认展示第1页
        current_page = 1
    # 总数据量
    total_count = models.Publisher.objects.count()
    # 定义每页显示多少条数据
    per_page = 10
    # 计算出总页码数
    total_page, more = divmod(total_count, per_page)
    if more:
        total_page += 1
    # 定义页面上最多显示多少页码(为了左右对称,一般设为奇数)
    max_show = 11
    half_show = max_show // 2
    # 计算一下页面显示的页码范围
    if total_page <= max_show:  # 总页码数小于最大显示页码数
        page_start = 1
        page_end = total_page
    elif current_page + half_show >= total_page:  # 右边越界
        page_end = total_page
        page_start = total_page - max_show
    elif current_page - half_show <= 1:  # 左边越界
        page_start = 1
        page_end = max_show
    else:  # 正常页码区间
        page_start = current_page - half_show
        page_end = current_page + half_show
    # 数据索引起始位置
    data_start = (current_page-1) * per_page
    data_end = current_page * per_page

    publisher_list = models.Publisher.objects.all()[data_start:data_end]

    # 生成页面上显示的页码
    page_html_list = []
    page_html_list.append('')
    page_html = "".join(page_html_list)
    return render(request, "publisher_list.html", {"publisher_list": publisher_list, "page_html": page_html})
class Pagination(object):
    """自定义分页(Bootstrap版)"""
    def __init__(self, current_page, total_count, base_url, per_page=10, max_show=11):
        """
        :param current_page: 当前请求的页码
        :param total_count: 总数据量
        :param base_url: 请求的URL
        :param per_page: 每页显示的数据量,默认值为10
        :param max_show: 页面上最多显示多少个页码,默认值为11
        """
        try:
            self.current_page = int(current_page)
        except Exception as e:
            # 取不到或者页码数不是数字都默认展示第1页
            self.current_page = 1
        # 定义每页显示多少条数据
        self.per_page = per_page
        # 计算出总页码数
        total_page, more = divmod(total_count, per_page)
        if more:
            total_page += 1
        self.total_page = total_page
        # 定义页面上最多显示多少页码(为了左右对称,一般设为奇数)
        self.max_show = max_show
        self.half_show = max_show // 2
        self.base_url = base_url

    @property
    def start(self):
        return (self.current_page-1) * self.per_page

    @property
    def end(self):
        return self.current_page * self.per_page

    def page_html(self):
        # 计算一下页面显示的页码范围
        if self.total_page <= self.max_show:  # 总页码数小于最大显示页码数
            page_start = 1
            page_end = self.total_page
        elif self.current_page + self.half_show >= self.total_page:  # 右边越界
            page_end = self.total_page
            page_start = self.total_page - self.max_show
        elif self.current_page - self.half_show <= 1:  # 左边越界
            page_start = 1
            page_end = self.max_show
        else:  # 正常页码区间
            page_start = self.current_page - self.half_show
            page_end = self.current_page + self.half_show
        # 生成页面上显示的页码
        page_html_list = []
        page_html_list.append('')
        return "".join(page_html_list)
def publisher_list(request):
    # 从URL中取当前访问的页码数
    current_page = int(request.GET.get('page'))
    # 比len(models.Publisher.objects.all())更高效
    total_count = models.Publisher.objects.count()
    page_obj = Pagination(current_page, total_count, request.path_info)
    data = models.Publisher.objects.all()[page_obj.start:page_obj.end]
    page_html = page_obj.page_html()
    return render(request, "publisher_list.html", {"publisher_list": data, "page_html": page_html})

  再来一版django内置分页器的分页

from django.shortcuts import render
from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger

L = []
for i in range(999):
    L.append(i)

def index(request):
    current_page = request.GET.get('p')

    paginator = Paginator(L, 10)
    # per_page: 每页显示条目数量
    # count:    数据总个数
    # num_pages:总页数
    # page_range:总页数的索引范围,如: (1,10),(1,200)
    # page:     page对象
    try:
        posts = paginator.page(current_page)
        # has_next              是否有下一页
        # next_page_number      下一页页码
        # has_previous          是否有上一页
        # previous_page_number  上一页页码
        # object_list           分页之后的数据列表
        # number                当前页
        # paginator             paginator对象
    except PageNotAnInteger:
        posts = paginator.page(1)
    except EmptyPage:
        posts = paginator.page(paginator.num_pages)
    return render(request, 'index.html', {'posts': posts})



    
    


    {% for item in posts %}
  • {{ item }}
  • {% endfor %}

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