标签：内置 obj self Django current book 组件 pager page

一、django内置序列化组件

1.前夕

前后端分离的情况下，两者交互只能通过json格式的数据，后端视图函数返回的数据应该是一个Json格式的大字典，那我们只能自己封装成大字典

from app01 import models
from django.http import JsonResponse


def ser_func(request):
    # 1。查询所有的书籍对象
    book_queryset = models.Book.objects.all()  # 结果为QuerySet对象 [数据对象1，数据对象2]
    # 2。封装成大字典返回
    data_dict = {}
    for book_obj in book_queryset:
        temp_dict = {}
        temp_dict['pk'] = book_obj.pk
        temp_dict['title'] = book_obj.title
        temp_dict['price'] = book_obj.price
        temp_dict['info'] = book_obj.info
        data_dict[book_obj.pk] = temp_dict  # {"1":{},"2":{}...}
    return JsonResponse(data_dict)

2.序列化组件

django自带的serializers.serialize()方法

# 导入内置序列化模块
from django.core import serializers

def ser_func(request):
    # 1。查询所有的书籍对象
    book_queryset = models.Book.objects.all()  # 结果为QuerySet对象 [数据对象1，数据对象2]
    # serializers.serialize()方法第一个参数，是序列化数据的格式
    res = serializers.serialize('json', book_queryset)
    return HttpResponse(res)

二、批量操作数据

1.循环插入

直接循环插入，10s 500条左右，效率很低

def bulk_data_func(request):
    for i in range(1, 10000):
        models.Book.objects.create(title="第%s本书" % i)
    book_queryset = models.Book.objects.all()
    return render(request, 'bulkPage.html', locals())

2.orm提供的操作

# orm提供的批量查询
def bulk_data_func(request):
    # 1.列表生成式生成对象，然后插入数据
    book_obj_list = [models.Book(title="第%i本书" % i) for i in range(1, 10000)]  # 通过类名加（）生成对象
    # 2 通过orm提供的批量操作插入
    models.Book.objects.bulk_create(book_obj_list)
    # 3.查询所有表中数据展示到前端
    book_queryset = models.Book.objects.all()
    return render(request, 'bulkPage.html', locals())

三、分页器

1.分页器思路

推导流程
	1.queryset支持切片操作(正数)
	2.研究各个参数之间的数学关系
 		每页固定展示多少条数据、起始位置、终止位置
 	3.自定义页码参数
    	current_page = request.GET.get('page')
 	4.前端展示分页器样式
	5.总页码数问题
    	divmod方法
 	6.前端页面页码个数渲染问题
    	后端产生 前端渲染

分页器后端

# 分页器
def bulk_data_func(request):
    # 1.查询出所有表中的数据，并展示到前端
    # 3.获取书籍总数量
    book_all = models.Book.objects.all()
    book_count = book_all.count()

    per_page_num = 10  # 没页展示多少数据
    # 4.开始分页
    all_page_num, extra_num = divmod(book_count, per_page_num)
    if extra_num:
        all_page_num += 1

    current_page = request.GET.get('page', 1)  # 获取'page'键对应的值，如果没有则默认为1



    # 2.前端拿到的是字符串，所以需要转换成整型，并且需要异常捕获防止一样
    try:
        current_page = int(current_page)
    except BaseException:
        current_page = 1
    start_num = (current_page - 1) * per_page_num
    end_num = current_page * per_page_num
    book_queryset = book_all[start_num:end_num]

    # 5 在模版上通过添加标签，并通过过滤器取消转义添加分页页码
    html_str = ''
    real_page = current_page
    if real_page<6:
        real_page=6
    for i in range(real_page - 5, real_page + 6):
        if current_page==i:
            html_str += '<li class="active"><a href="?page=%s">%s</a></li>' % (i, i)
        else:
            html_str += '<li><a href="?page=%s">%s</a></li>' % (i, i)
    return render(request, 'bulkPage.html', locals())

前端

{% for book_obj in book_queryset %}
   <p class="text-center">{{ book_obj.title }}</p>
{% endfor %}


{{ html_str|safe }}

2.自定义分页器使用

新建utils文件夹的自定义py文件内

class Pagination(object):
    def __init__(self, current_page, all_count, per_page_num=10, pager_count=11):
        """
        封装分页相关数据
        :param current_page: 当前页
        :param all_count:    数据库中的数据总条数
        :param per_page_num: 每页显示的数据条数
        :param pager_count:  最多显示的页码个数
        """
        try:
            current_page = int(current_page)
        except Exception as e:
            current_page = 1

        if current_page < 1:
            current_page = 1

        self.current_page = current_page

        self.all_count = all_count
        self.per_page_num = per_page_num

        # 总页码
        all_pager, tmp = divmod(all_count, per_page_num)
        if tmp:
            all_pager += 1
        self.all_pager = all_pager

        self.pager_count = pager_count
        self.pager_count_half = int((pager_count - 1) / 2)

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

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

    def page_html(self):
        # 如果总页码 < 11个：
        if self.all_pager <= self.pager_count:
            pager_start = 1
            pager_end = self.all_pager + 1
        # 总页码  > 11
        else:
            # 当前页如果<=页面上最多显示11/2个页码
            if self.current_page <= self.pager_count_half:
                pager_start = 1
                pager_end = self.pager_count + 1

            # 当前页大于5
            else:
                # 页码翻到最后
                if (self.current_page + self.pager_count_half) > self.all_pager:
                    pager_end = self.all_pager + 1
                    pager_start = self.all_pager - self.pager_count + 1
                else:
                    pager_start = self.current_page - self.pager_count_half
                    pager_end = self.current_page + self.pager_count_half + 1

        page_html_list = []
        # 添加前面的nav和ul标签
        page_html_list.append('''
                    <nav aria-label='Page navigation>'
                    <ul class='pagination'>
                ''')
        first_page = '<li><a href="?page=%s">首页</a></li>' % (1)
        page_html_list.append(first_page)

        if self.current_page <= 1:
            prev_page = '<li class="disabled"><a href="#">上一页</a></li>'
        else:
            prev_page = '<li><a href="?page=%s">上一页</a></li>' % (self.current_page - 1,)

        page_html_list.append(prev_page)

        for i in range(pager_start, pager_end):
            if i == self.current_page:
                temp = '<li class="active"><a href="?page=%s">%s</a></li>' % (i, i,)
            else:
                temp = '<li><a href="?page=%s">%s</a></li>' % (i, i,)
            page_html_list.append(temp)

        if self.current_page >= self.all_pager:
            next_page = '<li class="disabled"><a href="#">下一页</a></li>'
        else:
            next_page = '<li><a href="?page=%s">下一页</a></li>' % (self.current_page + 1,)
        page_html_list.append(next_page)

        last_page = '<li><a href="?page=%s">尾页</a></li>' % (self.all_pager,)
        page_html_list.append(last_page)
        # 尾部添加标签
        page_html_list.append('''
                                           </nav>
                                           </ul>
                                       ''')
        return ''.join(page_html_list)

view.py中

def ab_pg_func(request):
    book_queryset = models.Books01.objects.all()
    from app01.utils.mypage import Pagination
    current_page = request.GET.get('page')
    page_obj = Pagination(current_page=current_page, all_count=book_queryset.count())
    page_queryset = book_queryset[page_obj.start:page_obj.end]
    return render(request, 'pgPage.html', locals())


{% for book_obj in page_queryset %}
   <p>{{ book_obj.title }}</p>
{% endfor %}
{{ page_obj.page_html|safe }}

四、form组件

1.功能

自动校验数据
自动生成标签
自动展示信息

2.自动校验数据

（1）forms模块的关键字

is_valid 是否合法，只要有一个不符合结果都是false
cleaned_data 获取符合校验条件的数据
errors 获取不符合校验规则的数据

（2）例

views.py

class MyForm(forms.Form):
    # 代表username字段最少三个字符最大八个字符
    username = forms.CharField(min_length=3, max_length=8)
    # age字段最小为0 最大为200
    age = forms.IntegerField(min_value=0, max_value=200)
    # email字段必须符合邮箱格式
    email = forms.EmailField()

测试

    # 测试views中的form组件
    from app01 import views
    form_obj = views.MyForm({'username':'jason','age':18,'email':'123'})

    # 1.判断数据是否全部符合要求
    res = form_obj.is_valid()
    print(res)  # False

    # 2.获取全部符合校验条件的数据
    res1 = form_obj.cleaned_data
    print(res1)  # {'username': 'jason', 'age': 18}

    # 3.获取不符合校验规则的数据及其原因
    res2 = form_obj.errors
    print(res2)  
    # <ul class="errorlist"><li>email<ul class="errorlist"><li>Enter a valid email address.</li></ul></li></ul>

标签：内置,obj,self,Django,current,book,组件,pager,page
From： https://www.cnblogs.com/DuoDuosg/p/16995080.html

Django框架：内置组件