Django 操作数据库-原生SQL初体验

2018-12-15 本文已影响0人前端程序猿

一、安装 `mysqlclient`

pip install mysqlclient

二、配置连接数据库

mysite/settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        # 数据库名
        'NAME': 'django_db1',
        'USER': 'root',
        'PASSWORD': '123456',
        'HOST': '127.0.0.1',
        'PORT': '3306',
    }
}

三、使用原生 `sql` 操作数据库

使用 navicat 新建数据库 django_db1
在数据库 django_db1 新建表 book

新增数据：

front/views.py

from django.shortcuts import render
from django.db import connection


def index(request):
    cursor = connection.cursor()
    cursor.execute("insert into book(title,author) values('深入理解ES6', '尼古拉斯')")
    return render(request, 'front/index.html')

浏览器访问： localhost:8000, 便会新增一条数据

查询数据

front/views.py

def index(request):
cursor = connection.cursor()
cursor.execute("select * from book")
# 查询一条数据
# row = cursor.fetchone()
# 指定查询的条数
# rows = cursor.fetchmany(2)
# 查询所有数据
rows = cursor.fetchall()
for row in rows:
    print(row)
return render(request, 'front/index.html')

四、`Python DB API`下 `cursor`对象，常用接口

description

执行 cursor.execute后，可通过 cursor.description 查看字段信息

front/views.py

def index(request):
cursor = connection.cursor()
cursor.execute("select * from book")
# (('id', 3, 1, 11, 11, 0, 0), ('title', 253, 15, 765, 765, 0, 0), ('author', 253, 12, 765, 765, 0, 0))
print(cursor.description)
rows = cursor.fetchall()
for row in rows:
    print(row)
return render(request, 'front/index.html')

rowcount

执行 sql 删除，新增，修改时，返回受影响的条数，查询时，返回查询数据的条数

front/views.py

def index(request):
cursor = connection.cursor()
cursor.execute("delete from book where id=2")
# 1
print(cursor.rowcount)
return render(request, 'front/index.html')

close

关闭游标
```
cursor.close()
```

execute

用于执行 sql 语句，还可以传递参数

cursor.execute('select * from book where id=%s', (1,))

fetchone
fetchmany

fetchall

# 查询一条数据
row = cursor.fetchone()
# 指定查询的条数
rows = cursor.fetchmany(2)
# 查询所有数据
rows = cursor.fetchall()

五、图书管理系统案例

进入虚拟环境
```
workon myenv
```
创建一个新的项目
```
django-admin startproject book_manager
```

创建 front 应用

cd book_manager
python manage.py startapp front

配置将 front 应用，注册到已安装应用
book_manager/setting.py
```
INSTALLED_APPS = [
    'front',
]
```

使用 Navicat 创建数据库 book_manager
创建表 book, 三个字段： id、 title、 author

配置数据库连接
book_manager/settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        # 数据库名
        'NAME': 'book_manager',
        'USER': 'root',
        'PASSWORD': '123456',
        'HOST': '127.0.0.1',
        'PORT': '3306',
    }
}

配置路由

book_manager/urls.py

from django.urls import path, include

urlpatterns = [
    path('', include('front.urls')),
]

front/urls.py

from django.urls import path
from . import views

app_name = 'front'

urlpatterns = [
   path('', views.index, name='index'),
   path('create/', views.create_book, name='create'),
   path('detail/<int:book_id>', views.book_detail, name='detail'),
   path('delete/<int:book_id>', views.book_delete, name='delete'),
   path('edit/<int:book_id>', views.book_edit, name='edit'),
]

编写视图函数

front/views.py

from django.shortcuts import render, reverse, redirect
from django.db import connection


# 获取操作数据库锚点
def get_cursor():
    return connection.cursor()

# 首页，展示所有图书
def index(request):
    cursor = get_cursor()
    cursor.execute('select * from book')
    keys = [item[0] for item in cursor.description]
    books = [dict(zip(keys, values)) for values in cursor.fetchall()]
    cursor.close()
    return render(request, 'front/index.html', context={"books": books})

# 新增图书
def create_book(request):
    if request.method == 'POST':
        title = request.POST.get('title')
        author = request.POST.get('author')
        cursor = get_cursor()
        cursor.execute('insert into book(title, author) values(%s, %s)', (title, author))
        cursor.close()
        return redirect(reverse('front:index'))
    else:
        return render(request, 'front/create.html')

# 图书详情
def book_detail(request, book_id):
    cursor = get_cursor()
    cursor.execute('select * from book where id=%s', (book_id,))
    keys = [item[0] for item in cursor.description]
    book = dict(zip(keys, cursor.fetchone()))
    cursor.close()
    return render(request, 'front/detail.html', context={"book": book})

# 删除图书
def book_delete(request, book_id):
    cursor = get_cursor()
    cursor.execute('delete from book where id=%s', (book_id,))
    cursor.close()
    return redirect(reverse('front:index'))

# 编辑图书
def book_edit(request, book_id):
    cursor = get_cursor()
    if request.method == 'GET':
        cursor.execute('select * from book where id=%s', (book_id,))
        keys = [item[0] for item in cursor.description]
        book = dict(zip(keys, cursor.fetchone()))
        cursor.close()
        return render(request, 'front/edit.html', context={"book": book})
    else:
        title = request.POST.get('title')
        author = request.POST.get('author')
        cursor.execute('update book set title=%s, author=%s where id=%s', (title, author, book_id))
        cursor.close()
        return redirect(reverse('front:index'))

将 static 注册为模板标签
book_manager/settings.py

TEMPLATES = [
    {
        'OPTIONS': {
            'builtins': [
                'django.templatetags.static'
            ],
        },
    },
]

关闭表单 csrf 验证
book_manager/settings.py

MIDDLEWARE = [
    # 'django.middleware.csrf.CsrfViewMiddleware',
]

编写模板
front/templates/front/base.html

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>图书管理系统</title>
        <link rel="stylesheet" href="{% static 'front/style.css' %}">
    </head>
    <body>
        {% include 'front/header.html' %}
        {% block content %}
        {% endblock %}
    </body>
    </html>

front/templates/front/header.html

     <header>
        <nav>
            <ul>
                <li><a href="/">首页</a></li>
                <li><a href="/create/">新增图书</a></li>
            </ul>
        </nav>
    </header>

front/templates/front/index.html

    {% extends "front/base.html" %}

    {% block content %}
        <h1>所有图书</h1>
        <table cellpadding="0" cellspacing="0" >
            <thead>
                <tr>
                    <th class="table-id">序号</th>
                    <th class="table-title">书名</th>
                    <th class="table-author">作者</th>
                </tr>
            </thead>
            <tbody>
                {% for book in books %}
                    <tr>
                        <td class="table-id">{{ forloop.counter }}</td>
                        <td class="table-title"><a href="{% url 'front:detail' book_id=book.id %}">{{ book.title }}</a></td>
                        <td class="table-author">{{ book.author }}</td>
                    </tr>
                {% endfor %}
            </tbody>
        </table>
    {% endblock %}

front/templates/front/create.html

    {% extends "front/base.html" %}

    {% block content %}
        <h1>新增图书</h1>
        <form action="" method="post" id="create-form">
            <p>
                <label for="title"> 书名：
                    <input type="text" class="input-text" name="title" id="title" required>
                </label>
            </p>
            <p>
                <label for="author"> 作者：
                    <input type="text" class="input-text" name="author" id="author" required>
                </label>
            </p>
            <p>
                <input type="submit" value="新增图书" class="default-btn">
            </p>
        </form>
    {% endblock %}

front/templates/front/detail.html

    {% extends "front/base.html" %}

    {% block content %}
        <h1>图书详情</h1>
        <table cellspacing="0" cellpadding="0">
            {% for key, value in book.items %}
                <tr>
                    <td class="table-id">{{ key }}</td>
                    <td class="table-title">{{ value }}</td>
                </tr>
            {% endfor %}
            <tr>
                <td class="table-id"><button id="book-del" class="small-danger-btn">删除</button></td>
                <td class="table-title"><button id="book-edit" class="small-default-btn">编辑</button></td>
            </tr>
        </table>

        <script>
            const delBtn = document.querySelector('#book-del');
            const editBtn = document.querySelector('#book-edit');

            delBtn.onclick = function() {
                window.location.href = '{% url 'front:delete' book_id=book.id %}'
            };

            editBtn.onclick = function() {
                window.location.href = '{% url 'front:edit' book_id=book.id %}'
            };
        </script>
    {% endblock %}

front/templates/front/edit.html

    {% extends "front/base.html" %}

    {% block content %}
        <h1>编辑图书</h1>
        <form action="{% url 'front:edit' book_id=book.id %}" method="post" id="create-form">
            <p>
                <label for="title"> 书名：
                    <input type="text" class="input-text" value="{{ book.title }}" name="title" id="title" required>
                </label>
            </p>
            <p>
                <label for="author"> 作者：
                    <input type="text" class="input-text" value="{{ book.author }}" name="author" id="author" required>
                </label>
            </p>
            <p>
                <input type="submit" value="编辑图书" class="default-btn">
            </p>
        </form>
    {% endblock %}

front/static/front/style.css

    body, ul, li, h1{
        padding: 0;
        margin: 0;
    }

    nav ul {
        list-style: none;
        height: 60px;
        background-color: #333;
    }

    nav li {
        padding: 0 10px;
        float: left;
        text-align: center;
        line-height: 60px;
    }

    nav a {
        width: 120px;
        display: block;
        height: 60px;
        font-size: 22px;
        color: #fff;
        font-weight: bold;
        text-decoration: none;
    }

    nav a:hover {
        color: lightblue;
    }

    #create-form {
        width: 600px;
        height: 300px;
        background-color: #abcdef;
        margin: 15px auto;
    }

    #create-form p {
        text-align: center;
        padding-top:  25px;
    }

    .input-text {
        width: 200px;
        height: 30px;
        border-radius: 5px;
        border: 1px solid lightblue;
    }

    .default-btn {
        width: 150px;
        height: 50px;
        border-radius: 10px;
        color: #fff;
        background-color: lightgreen;
        line-height: 30px;
        text-align: center;
        border: 1px solid #89a1a9;
    }

    .small-default-btn {
        width: 100px;
        height: 35px;
        border-radius: 10px;
        color: #fff;
        background-color: lightgreen;
        line-height: 30px;
        text-align: center;
        border: 1px solid #89a1a9;
    }

    .small-danger-btn {
        width: 100px;
        height: 35px;
        border-radius: 10px;
        color: #fff;
        background-color: darkred;
        line-height: 30px;
        text-align: center;
        border: 1px solid #89a1a9;
    }

    table {
        margin: 25px auto;
    }

    td, th {
        border: 1px solid lightblue;
        text-align: center;
    }

    .table-id {
        width: 100px;
        height: 50px;
    }

    .table-title {
        width: 500px;
        height: 50px;
    }

    .table-author {
        width: 300px;
        height: 50px;
    }


    h1 {
        text-align: center;
        color: #333;
    }

Django 操作数据库-原生SQL初体验

一、安装 `mysqlclient`

二、配置连接数据库

三、使用原生 `sql` 操作数据库

四、`Python DB API`下 `cursor`对象，常用接口

五、图书管理系统案例

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热点阅读

Django 操作数据库-原生SQL初体验

一、安装 mysqlclient

二、 配置连接数据库

三、使用原生 sql 操作数据库

四、Python DB API下 cursor对象，常用接口

五、图书管理系统案例

猜你喜欢

热点阅读

一、安装 `mysqlclient`

二、配置连接数据库

三、使用原生 `sql` 操作数据库

四、`Python DB API`下 `cursor`对象，常用接口