Django之ajax

一.MTV与MVC(了解)

   

   MTV模型(django):
        M:模型层(models.py)
        T:templates
        V:views
   MVC模型:
        M:模型层(models.py)
        V:视图层(views.py)
        C:控制器(Controller) urls.py
   本质:django的MTV也是MVC

二. 多对多表三种创建方式:

     1.第一种 django orm自动帮我们创建:

        class Book(models.Model):
        name = models.CharField(max_length=32)
        authors = models.ManyToManyField(to='Author')


        class Author(models.Model):
            name = models.CharField(max_length=32)

      2.第二种纯手动创建第三张表 (可新增字段,但不可按orm语句进行查询):

        class Book(models.Model):
            name = models.CharField(max_length=32)

        class Author(models.Model):
            name = models.CharField(max_length=32)

        class Book2Author(models.Model):
            book = models.ForeignKey(to='Book')
            author = models.ForeignKey(to='Author')
            info = models.CharField(max_length=32)

    3.第三种半自动创建第三张表(可扩展性高，并且能够符合orm查询):

        class Book(models.Model):
            name = models.CharField(max_length=32)
            # 第三种创建表的方式
            authors = models.ManyToManyField(to='Author',through='Book2Author',through_fields=('book','author'))

        class Author(models.Model):
            name = models.CharField(max_length=32)
            # book = models.ManyToManyField(to='Book',through='Book2Author',through_fields=('author','book'))


        class Book2Author(models.Model):
            book = models.ForeignKey(to='Book')
            author = models.ForeignKey(to='Author')
            info = models.CharField(max_length=32)

三.前后端传输数据编码格式contentType:

    urlencoded
        对应的数据格式:name=jason&password=666
        后端获取数据:request.POST
        ps；django会将urlencoded编码的数据解析自动放到request.POST
    formdata
        form表单传输文件的编码格式
        后端获取文件格式数据:request.FILES
        后端获取普通键值对数据:request.POST
    application/json
        ajax发送json格式数据
        需要注意的点
            编码与数据格式要一致

四. ajax (Asynchronous Javascript  And XML)

        1.前端有哪些方式可以朝后端发请求:

            浏览器窗口手动输入网址              get请求
            a标签的href属性                   get请求
            form表单                       get/post请求(默认是get请求)
            ajax                           get/post请求

         2.ajax特点:

          异步提交
          局部刷新

         3.ajax基本语法 :

            提交的地址(url)
            提交的方式(type)
            提交的数据(data)
            回调函数(success)
            $('#d1').click(function () {
                    $.ajax({
                        // 提交的地址
                        url:'/index/',
                        // 提交的方式
                        type:'post',
                        // 提交的数据
                        data:{'name':'jason','password':'123'},
                        // 回调函数
                        success:function (data) {  // data接收的就是异步提交返回的结果
                            alert(data)
                        }
                    })
                }
                

          4.ajax默认传输数据的编码格式也是urlencoded

          小练习:

              前端:

<input type="text" id="i1">+<input type="text" id="i2">=<input type="text" id="i3">

<button id="d1">加我加我~</button>

<script>
    $('#d1').click(function () {
        
        $.ajax({
            url: '',
            type: 'post',
            data: {'i1': $('#i1').val(), 'i2': $('#i2').val()},
            success: function (data) { $('#i3').val(data)}
            #接受到的就是后端res传来的值
        })
    })
</script>

               后端:

def index(request):
        if request.method == 'POST':
            i1=request.POST.get('i1')
            i2=request.POST.get('i2')
            i1=int(i1)
            i2=int(i2)
            res=i1+i2
            return HttpResponse(res)
        return render(request,'index.html')

            效果:

  

      5.前后端传输数据,数据是什么格式就应该告诉别人是什么格式(数据与编码要一一对应):

            a.   ajax传输json格式数据:

              前端:

<script>
            $('#d1').click(function () {
                   $.ajax({
                       url:'',  // url参数可以不写，默认就是当前页面打开的地址
                       type:'post',
                       contentType:'application/json',
                       data:JSON.stringify({'name':'jason','hobby':'study'}),
                       success:function (data) {
                            alert(data)
                       }
                   })
                })
</script>

            后端:

def index(request):
        if request.method == 'POST':

            print(request.body)  #json格式只有通过request.body才能查看
            res=json.loads(request.body.decode('utf-8'))
            hobby=res.get('hobby')
            print(hobby)
            return HttpResponse('OK')   #必须返回HttpResponse对象
        return render(request,'index.html')

          b.  ajax传输文件

          前端:

<input type="file" name="myfile" id="i1">
<button id="d1">提交~</button>
{#<button id="d1">选我选我~</button>#}

<script>
        $('#d1').click(function () {
                   var formdata = new FormData();
                   // FormData对象不仅仅可以传文件还可以传普通的键值对
                    formdata.append('name','jason');
                    // 获取input框存放的文件
                    //$('#i1')[0]由Jquery对象变为js对象
                    formdata.append('myfile',$('#i1')[0].files[0]);
                    $.ajax({
                        url:'',
                        type:'post',
                        data:formdata,
                        // ajax发送文件需要修改两个固定的参数
                        processData:false,  // 告诉浏览器不要处理我的数据
                        contentType:false,  // 不要用任何的编码，就用我formdata自带的编码格式，django能够自动识别改formdata对象
                        // 回调函数
                        success:function (data) {
                            alert(data)
                        }
                    })
                })
</script>

          后端:

def index(request):
        if request.method == 'POST':

            print(request.POST)    # 普通的键值对:<QueryDict: {'name': ['jason']}>
            print(request.FILES)
# 传文件< MultiValueDict: {'myfile': [ < InMemoryUploadedFile: day17课件.md(application / octet - stream) >]} >
            return HttpResponse('OK')   
        return render(request,'index.html')

       6.  form表单与ajax异同点:

     1.form表单不支持异步提交局部刷新
     2.form表单不支持传输json格式数据
     3.form表单与ajax默认传输数据的编码格式都是urlencoded

 五.批量插入数据:

   1.正常插数据:

      前端:

<div class="container">
    <div class="row">
        <div class="col-md-8 col-md-offset-2">
            <table class="table table-hover table-bordered table-striped">
                <thead>
                    <tr>
                        <th>id</th>
                        <th>name</th>
                    </tr>
                </thead>
                <tbody>
                    {% for book in book_list %}
                    <tr>
                        <td>{{ book.pk }}</td>
                        <td>{{ book.name }}</td>
                    </tr>
                    {% endfor %}
                </tbody>
            </table>

        </div>
    </div>
</div>

      后端:

def book2(request):

    for i in range(100):
       models.Book2.objects.create(name='第%s本书'%i)
    book_list=models.Book2.objects.all()
    return render(request, 'book2.html',locals())

      2.批量处理:

def test(request):
    l = []
    for i in range(1000):
        l.append(models.Book(name='第%s本书'%i))
    models.Book.objects.bulk_create(l)
    book_list=models.Book.objects.all()
    return render(request, 'book.html',locals())

六.分页器

   

utils / my_page

class Pagination(object):
    def __init__(self, current_page, all_count, per_page_num=9, 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

        用法:
        queryset = model.objects.all()
        page_obj = Pagination(current_page,all_count)
        page_data = queryset[page_obj.start:page_obj.end]
        获取数据用page_data而不再使用原始的queryset
        获取前端分页样式用page_obj.page_html
        """
        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)

views.py:

from django.shortcuts import render
from app01 import models
from app01.utils import my_page

# Create your views here.
def test(request):
    book_list = models.Book.objects.all()
    all_count = book_list.count()
    current_page = request.GET.get('page',1)
    page_obj = my_page.Pagination(current_page=current_page,all_count=all_count)
    page_queryset = book_list[page_obj.start:page_obj.end]
    return render(request,'book.html',locals())

  book.html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
    <link href="https://cdn.bootcss.com/twitter-bootstrap/3.4.1/css/bootstrap.min.css" rel="stylesheet">
    <script src="https://cdn.bootcss.com/twitter-bootstrap/3.4.1/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
    <div class="row">
        <div class="col-md-8 col-md-offset-2">
            <table class="table table-hover table-bordered table-striped">
                <thead>
                    <tr>
                        <th>id</th>
                        <th>name</th>
                    </tr>
                </thead>
                <tbody>
                    {% for book in page_queryset %}
                    <tr>
                        <td>{{ book.pk }}</td>
                        <td>{{ book.name }}</td>
                    </tr>
                    {% endfor %}
                </tbody>
            </table>
            {{ page_obj.page_html|safe }}
        </div>
    </div>
</div>

</body>
</html>

相关知识点:

    all_count = models.Book2.objects.all().count()
     # 要访问的当前页
     current_page = request.GET.get('page', 1)  # 用户不传默认展示第一页
     current_page = int(current_page)
     # 每页展示多少条数据
     per_page_num = 10

     # 获取总页数
     pager_nums,more = divmod(all_count,per_page_num)
     if more:
         pager_nums += 1

     html = ''
     for i in range(1,pager_nums+1):
         html += '<li><a href="?page=%s">%s</a></li>'%(i,i)
     # 起始位置
     page_start = (current_page-1)*per_page_num
     # 终止位置
     page_end = current_page*per_page_num

     book_list = models.Book2.objects.all()[page_start:page_end]

     return render(request,'booklist.html',locals())