Python - Django - ORM 实例

Posted 2021-10-25 sch01ar

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在 app01/models.py 中添加 Book 类对象表

from django.db import models

# Create your models here.


# 出版社
class Publisher(models.Model):
    id = models.AutoField(primary_key=True)  # 自增的 ID 主键
    # 创建一个 varchar(64) 的唯一的不为空的字段
    name = models.CharField(max_length=64, null=False, unique=True)


# 书籍
class Book(models.Model):
    id = models.AutoField(primary_key=True)  # 自增的 ID 主键
    # 创建一个 varchar(64) 的唯一的不为空的字段
    title = models.CharField(max_length=64, null=False, unique=True)
    # 和出版社关联的外键字段
    publisher = models.ForeignKey(to="Publisher")

然后执行命令更新到数据库中

[email protected] > makemigrations
[email protected] > migrate

在 Book 表中添加 3 条数据

展示书籍列表：

创建 book_list.html：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>书籍列表</title>
</head>
<body>

<table border="1">
    <thead>
    <tr>
        <th>id</th>
        <th>书名</th>
        <th>出版社</th>
    </tr>
    </thead>
    <tbody>
    {% for book in book_list %}
        <tr>
        <td>{{ book.id }}</td>
        <td>{{ book.title }}</td>
        <td>{{ book.publisher.name }}</td>
        </tr>
    {% endfor %}
    </tbody>
</table>
</body>
</html>

这里的 book.publisher 获取到的是 Publisher 对象，因为 publisher 关联了 Publisher 对象

在 app01/views.py 中添加 book_list 函数

from django.shortcuts import render, redirect, HttpResponse
from app01 import models


# 展示出版社列表
def publisher_list(request):
    # 去数据库查出所有的出版社，填充到 html 中，返回给用户
    ret = models.Publisher.objects.all().order_by("id")  # order_by("id") 通过 id 进行排序
    return render(request, "publisher_list.html", {"publisher_list": ret})


# 添加新的出版社
def add_publisher(request):
    # 如果是 POST 请求，就获取用户填写的数据
    if request.method == "POST":
        new_publisher = request.POST.get("publisher_name")
        # 获得数据后去数据库中新增一条数据
        models.Publisher.objects.create(name=new_publisher)
        # 添加成功后进行跳转
        return redirect("/publisher_list/")

    # 用户来到该界面返回的 html 页面
    return render(request, "add_publisher.html")


# 删除出版社
def del_publisher(request):
    # 从 GET 请求的参数中拿到要删除的 id 值
    del_id = request.GET.get(‘id‘)
    # 如果取到 id 值，就去数据库中删除该 id 的数据
    if del_id:
        # 根据 id 查找数据，并删除
        del_obj = models.Publisher.objects.get(id=del_id).delete()
        # 删除后返回页面
        return redirect("/publisher_list/")
    else:
        return HttpResponse("要删除的数据不存在！")


# 编辑出版社
def edit_publisher(request):
    # 获取 POST 发来的数据，并更新到数据库中
    if request.method == "POST":
        # 获取 POST 传送来的 id 值和出版社
        edit_id = request.POST.get(‘id‘)
        new_name = request.POST.get(‘publisher_name‘)
        # 根据 id 取得出版社
        publisher = models.Publisher.objects.get(id=edit_id)
        publisher.name = new_name
        publisher.save()  # 把修改的结果提交到数据库
        return redirect("/publisher_list/")  # 跳转到列表页面

    # 从 GET 请求中取得 id 值
    publisher_id = request.GET.get(‘id‘)
    if publisher_id:
        # 获取当前编辑的出版社对象
        publisher_obj = models.Publisher.objects.get(id=publisher_id)
        return render(request, "edit_publisher.html", {"publisher": publisher_obj})
    else:
        return HttpResponse("编辑的出版社不存在！")


# 展示书籍列表
def book_list(request):
    # 去数据库中查询所有书籍
    all_book = models.Book.objects.all()
    # 渲染数据
    return render(request, "book_list.html", {"book_list": all_book})

在 mysite0/urls.py 中添加对应关系

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
    url(r‘^publisher_list/‘, views.publisher_list),
    url(r‘^add_publisher/‘, views.add_publisher),
    url(r‘^del_publisher/‘, views.del_publisher),
    url(r‘^edit_publisher/‘, views.edit_publisher),
    url(r‘^book_list/‘, views.book_list),
]

运行结果：

技术图片

添加书籍：

修改 book_list.html：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>书籍列表</title>
</head>
<body>

<table border="1">
    <thead>
    <tr>
        <th>id</th>
        <th>书名</th>
        <th>出版社</th>
    </tr>
    </thead>
    <tbody>
    {% for book in book_list %}
        <tr>
        <td>{{ book.id }}</td>
        <td>{{ book.title }}</td>
        <td>{{ book.publisher.name }}</td>
        </tr>
    {% endfor %}
    </tbody>
</table>

<a href="/add_book/">添加书籍</a>

</body>
</html>

创建 add_book.html：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>添加书籍</title>
</head>
<body>

<h1>添加书籍</h1>

<form action="/add_book/" method="post">
    <p>
        书名:<input type="text" name="book_title">
    </p>
    <p>
        出版社:
        <select name="publisher" >
            {% for publisher in publisher_list %}
                <option value="{{ publisher.id }}">{{ publisher.name }}</option>
            {% endfor %}
        </select>
    </p>
    <p>
         <input type="submit" value="提交">
    </p>

</form>

</body>
</html>

在 app01/views.py 中添加 add_book 函数

from django.shortcuts import render, redirect, HttpResponse
from app01 import models


# 展示出版社列表
def publisher_list(request):
    # 去数据库查出所有的出版社，填充到 html 中，返回给用户
    ret = models.Publisher.objects.all().order_by("id")  # order_by("id") 通过 id 进行排序
    return render(request, "publisher_list.html", {"publisher_list": ret})


# 添加新的出版社
def add_publisher(request):
    # 如果是 POST 请求，就获取用户填写的数据
    if request.method == "POST":
        new_publisher = request.POST.get("publisher_name")
        # 获得数据后去数据库中新增一条数据
        models.Publisher.objects.create(name=new_publisher)
        # 添加成功后进行跳转
        return redirect("/publisher_list/")

    # 用户来到该界面返回的 html 页面
    return render(request, "add_publisher.html")


# 删除出版社
def del_publisher(request):
    # 从 GET 请求的参数中拿到要删除的 id 值
    del_id = request.GET.get(‘id‘)
    # 如果取到 id 值，就去数据库中删除该 id 的数据
    if del_id:
        # 根据 id 查找数据，并删除
        del_obj = models.Publisher.objects.get(id=del_id).delete()
        # 删除后返回页面
        return redirect("/publisher_list/")
    else:
        return HttpResponse("要删除的数据不存在！")


# 编辑出版社
def edit_publisher(request):
    # 获取 POST 发来的数据，并更新到数据库中
    if request.method == "POST":
        # 获取 POST 传送来的 id 值和出版社
        edit_id = request.POST.get(‘id‘)
        new_name = request.POST.get(‘publisher_name‘)
        # 根据 id 取得出版社
        publisher = models.Publisher.objects.get(id=edit_id)
        publisher.name = new_name
        publisher.save()  # 把修改的结果提交到数据库
        return redirect("/publisher_list/")  # 跳转到列表页面

    # 从 GET 请求中取得 id 值
    publisher_id = request.GET.get(‘id‘)
    if publisher_id:
        # 获取当前编辑的出版社对象
        publisher_obj = models.Publisher.objects.get(id=publisher_id)
        return render(request, "edit_publisher.html", {"publisher": publisher_obj})
    else:
        return HttpResponse("编辑的出版社不存在！")


# 展示书籍列表
def book_list(request):
    # 去数据库中查询所有书籍
    all_book = models.Book.objects.all()
    print(all_book)
    # 渲染数据
    return render(request, "book_list.html", {"book_list": all_book})


# 添加书籍
def add_book(request):
    if request.method == "POST":
        new_title = request.POST.get("book_title")
        new_publisher_id = request.POST.get("publisher")
        # 去数据库中创建数据
        models.Book.objects.create(title=new_title, publisher_id=new_publisher_id)
        return redirect("/book_list/")
    # 去数据库取得出版社数据展示在页面上以供用户选择
    publishers = models.Publisher.objects.all()
    return render(request, "add_book.html", {"publisher_list": publishers})

在 mysite0/urls.py 中添加对应关系

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
    url(r‘^admin/‘, admin.site.urls),
    url(r‘^publisher_list/‘, views.publisher_list),
    url(r‘^add_publisher/‘, views.add_publisher),
    url(r‘^del_publisher/‘, views.del_publisher),
    url(r‘^edit_publisher/‘, views.edit_publisher),
    url(r‘^book_list/‘, views.book_list),
    url(r‘^add_book/‘, views.add_book),
]

运行结果：

技术图片

点击“添加书籍”

技术图片

点击“提交”

技术图片

删除书籍：

修改 book_list.html：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>书籍列表</title>
</head>
<body>

<table border="1">
    <thead>
    <tr>
        <th>id</th>
        <th>书名</th>
        <th>出版社</th>
        <th>操作</th>
    </tr>
    </thead>
    <tbody>
    {% for book in book_list %}
        <tr>
        <td>{{ book.id }}</td>
        <td>{{ book.title }}</td>
        <td>{{ book.publisher.name }}</td>
        <td>
            <a href="/del_book/?id={{ book.id }}">删除</a>
        </td>
        </tr>
    {% endfor %}
    </tbody>
</table>

<a href="/add_book/">添加书籍</a>

</body>
</html>

在 app01/views.py 中添加 del_book 函数

from django.shortcuts import render, redirect, HttpResponse
from app01 import models


# 展示出版社列表
def publisher_list(request):
    # 去数据库查出所有的出版社，填充到 html 中，返回给用户
    ret = models.Publisher.objects.all().order_by("id")  # order_by("id") 通过 id 进行排序
    return render(request, "publisher_list.html", {"publisher_list": ret})


# 添加新的出版社
def add_publisher(request):
    # 如果是 POST 请求，就获取用户填写的数据
    if request.method == "POST":
        new_publisher = request.POST.get("publisher_name")
        # 获得数据后去数据库中新增一条数据
        models.Publisher.objects.create(name=new_publisher)
        # 添加成功后进行跳转
        return redirect("/publisher_list/")

    # 用户来到该界面返回的 html 页面
    return render(request, "add_publisher.html")


# 删除出版社
def del_publisher(request):
    # 从 GET 请求的参数中拿到要删除的 id 值
    del_id = request.GET.get(‘id‘)
    # 如果取到 id 值，就去数据库中删除该 id 的数据
    if del_id:
        # 根据 id 查找数据，并删除
        del_obj = models.Publisher.objects.get(id=del_id).delete()
        # 删除后返回页面
        return redirect("/publisher_list/")
    else:
        return HttpResponse("要删除的数据不存在！")


# 编辑出版社
def edit_publisher(request):
    # 获取 POST 发来的数据，并更新到数据库中
    if request.method == "POST":
        # 获取 POST 传送来的 id 值和出版社
        edit_id = request.POST.get(‘id‘)
        new_name = request.POST.get(‘publisher_name‘)
        # 根据 id 取得出版社
        publisher = models.Publisher.objects.get(id=edit_id)
        publisher.name = new_name
        publisher.save()  # 把修改的结果提交到数据库
        return redirect("/publisher_list/")  # 跳转到列表页面

    # 从 GET 请求中取得 id 值
    publisher_id = request.GET.get(‘id‘)
    if publisher_id:
        # 获取当前编辑的出版社对象
        publisher_obj = models.Publisher.objects.get(id=publisher_id)
        return render(request, "edit_publisher.html", {"publisher": publisher_obj})
    else:
        return HttpResponse("编辑的出版社不存在！")


# 展示书籍列表
def book_list(request):
    # 去数据库中查询所有书籍
    all_book = models.Book.objects.all()
    print(all_book)
    # 渲染数据
    return render(request, "book_list.html", {"book_list": all_book})


# 添加书籍
def add_book(request):
    if request.method == "POST":
        new_title = request.POST.get("book_title")
        new_publisher_id = request.POST.get("publisher")
        # 去数据库中创建数据
        models.Book.objects.create(title=new_title, publisher_id=new_publisher_id)
        return redirect("/book_list/")
    # 去数据库取得出版社数据展示在页面上以供用户选择
    publishers = models.Publisher.objects.all()
    return render(request, "add_book.html", {"publisher_list": publishers})


# 删除书籍
def del_book(request):
    # 从 URL 中获取要删除的书籍的 id
    del_id = request.GET.get("id")
    # 去数据库中删除指定 id 的书籍
    models.Book.objects.get(id=del_id).delete()
    # 跳转到书籍列表页面
    return redirect("/book_list/")

在 mysite0/urls.py 中添加对应关系

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
    url(r‘^admin/‘, admin.site.urls),
    url(r‘^publisher_list/‘, views.publisher_list),
    url(r‘^add_publisher/‘, views.add_publisher),
    url(r‘^del_publisher/‘, views.del_publisher),
    url(r‘^edit_publisher/‘, views.edit_publisher),
    url(r‘^book_list/‘, views.book_list),
    url(r‘^add_book/‘, views.add_book),
    url(r‘^del_book/‘, views.del_book),
]

运行结果：

技术图片

删除“php”

技术图片

页面闪了一下，PHP 就被删除了

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