Django ModelForm组件使用方法详解

更新时间：2020-07-18 01:18:01 作者：startmvc

一、创建ModelFormfromdjango.formsimportModelFormfromappxximportmodelsfromdjango.formsimportwidgetsaswdt#因为重名

一、创建ModelForm


from django.forms import ModelForm
from appxx import models
from django.forms import widgets as wdt # 因为重名，所以起个别名
#定义一个类，比如BookForm，这个类要继承ModelForm，在这个类中再写一个原类Meta（规定写法，注意首字母是大写的）
#在这个原类中，有以下属性（部分）：
class BookForm(ModelForm):
 class Meta:
 model = models.Book # 对应的Model中的类
 fields = "__all__" # 字段，如果是__all__，就表示列出所有的字段，或者使用列表列出想要的字段
 exclude = None # 排除的字段
 # error_messages用法
 error_messages = {
 "title": {"required": "书名不能为空"},
 "price": {"required": "售价不能为空"},
 }
 # widgets用法，比如把输入用户名的input框给为Textarea
 widgets = {
 "name": wdt.Textarea(attrs={"class": "c1"}) # 还可以自定义属性
 }
 #labels，自定义在前端显示的名字
 labels= {
 "title": "书名",
 "price": "售价",
 }

然后在 url 对应的视图函数中实例化这个类，把这个对象传给前端：


def add_book(request):
 form = forms.BookForm()
 return render(request, "add_book.html", {"form": form})

然后在前端像Form组件那样渲染页面

二、添加数据

保存数据的时候，不用挨个取数据了，只需要 save 一下即可。


from django.shortcuts import render,redirect
from appxx import models
from appxx import forms


def add_book(request):
 if request.method == "POST":
 form = forms.BookForm(request.POST)
 if form.is_valid():
 form.save()
 return redirect("/book/")
 form = forms.BookForm()
 return render(request, "add_book.html", {"form": form})

三、编辑数据

如果不使用 ModelForm，编辑的时候得显示之前的数据，还得挨个取一遍值；如果使用 ModelForm，只需要加一个instance=obj（obj是要修改的数据库的一条数据的对象）就可以得到同样的效果。

保存的时候要注意，一定要注意有这个对象（instance=obj），否则不知道更新哪一个数据。


from django.shortcuts import render,redirect
from appxx import models
from appxx import forms


def edit_book(request, edit_book_id):
 edit_book= models.Book.objects.filter(id=edit_book_id).first()
 if request.method == "POST":
 form = forms.BookForm(request.POST, instance=edit_book)
 if form.is_valid():
 form.save()
 return redirect("/book/")
 form = forms.BookForm(instance=edit_book)
 return render(request, "edit_book.html", {"form": form})

总结：从上边可以看到 ModelForm 用起来是非常方便的，比如增加修改之类的操作。但是也带来额外不好的地方，model和form之间耦合了。如果不耦合的话，form.save()方法也无法直接提交保存。但是耦合的话使用场景通常局限用于小程序，写大程序就最好不用了。

四、完整示例代码

项目结构

urls.py


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


urlpatterns = [
 url(r'^admin/', admin.site.urls),
 url(r"^book/$", views.book),
 url(r"^book/add/", views.add_book),
 url(r"^book/edit/(\d+)/", views.edit_book),
]

views.py


from django.shortcuts import render,redirect
from appxx import models
from appxx import forms


def book(request):
 book_list = models.Book.objects.all()
 return render(request, "book.html", {"book_list": book_list})


def add_book(request):
 if request.method == "POST":
 form = forms.BookForm(request.POST)
 if form.is_valid():
 form.save()
 return redirect("/book/")
 form = forms.BookForm()
 return render(request, "add_book.html", {"form": form})


def edit_book(request, edit_book_id):
 edit_book= models.Book.objects.filter(id=edit_book_id).first()
 if request.method == "POST":
 form = forms.BookForm(request.POST, instance=edit_book)
 if form.is_valid():
 form.save()
 return redirect("/book/")
 form = forms.BookForm(instance=edit_book)
 return render(request, "edit_book.html", {"form": form})

models.py


from django.db import models


class Book(models.Model):
 id = models.AutoField(primary_key=True)
 title = models.CharField(max_length=32)
 price = models.DecimalField(max_digits=5, decimal_places=2)
 publish_date = models.DateField()
 publisher = models.ForeignKey(to="Publisher")
 authors = models.ManyToManyField(to="Author")

 def __str__(self):
 return self.title


class Publisher(models.Model):
 id = models.AutoField(primary_key=True)
 name = models.CharField(max_length=32)

 def __str__(self):
 return self.name


class Author(models.Model):
 id = models.AutoField(primary_key=True)
 name = models.CharField(max_length=32)

 def __str__(self):
 return self.name

forms.py


from django.forms import ModelForm
from appxx import models
from django.forms import widgets as wdt


class BookForm(ModelForm):
 class Meta:
 model = models.Book
 fields = "__all__"
 labels = {
 "title": "书名",
 "price": "售价",
 "publish_date": "出版日期",
 "publisher": "出版社",
 "authors": "作者"
 }
 widgets = {
 "title": wdt.TextInput(attrs={"class": "form-control"}),
 "price": wdt.TextInput(attrs={"class": "form-control"}),
 "publish_date": wdt.TextInput(attrs={"class": "form-control", "type": "date"}),
 "publisher": wdt.Select(attrs={"class": "form-control"}),
 "authors": wdt.SelectMultiple(attrs={"class": "form-control"}),

 }
 error_messages = {
 "title": {"required": "书名不能为空"},
 "price": {"required": "售价不能为空"},
 "publish_date": {"required": "出版日期不能为空"},
 "publisher": {"required": "出版社不能为空"},
 "authors": {"required": "作者不能为空"},
 }

book.html


<!DOCTYPE html>
<html lang="zh-cn">
<head>
 <meta charset="UTF-8">
 <title>展示书籍</title>
 <link rel="stylesheet" href="/static/bootstrap/css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" >
</head>
<body>
<div class="container">
 <div class="row">
 <div class="col-md-6 col-md-offset-3">
 <span><a class="btn btn-primary" href="/book/add/" rel="external nofollow" >添加</a></span>
 <table class="table table-striped table-bordered">
 <thead>
 <tr>
 <th>序号</th>
 <th>书名</th>
 <th>售价</th>
 <th>出版日期</th>
 <th>出版社</th>
 <th>作者</th>
 <th>操作</th>
 </tr>
 </thead>
 <tbody>
 {% for book in book_list %}
 <tr>
 <td>{{ forloop.counter }}</td>
 <td>{{ book.title }}</td>
 <td>{{ book.price }}</td>
 <td>{{ book.publish_date }}</td>
 <td>{{ book.publisher.name }}</td>
 <td>
 {% for author in book.authors.all %}
 {{ author.name }}
 {% endfor %}
 </td>
 <td>
 <span><a class="btn btn-warning" href="/book/edit/{{ book.pk }}/" rel="external nofollow" >编辑</a></span>
 <span><a class="btn btn-danger" href="">删除</a></span>
 </td>
 </tr>
 {% endfor %}
 </tbody>
 </table>
 </div>
 </div>
</div>
</body>
</html>

add_book.html和edit_book.html（两个页面代码一样）


<!DOCTYPE html>
<html lang="zh-cn">
<head>
 <meta charset="UTF-8">
 <title>添加书籍</title>
 <link rel="stylesheet" href="/static/bootstrap/css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" >
 <style>
 .panel-title {
 font-weight: bolder;
 }

 .panel {
 margin-top: 30px;
 }
 </style>
</head>
<body>
<div class="container">
 <div class="row">
 {# panel开始 #}
 <div class="panel panel-danger col-sm-6 col-md-6 col-sm-offset-3 col-md-offset-3">
 <div class="panel-heading">
 <h3 class="panel-title">添加书籍</h3>
 </div>
 {# panel-body开始 #}
 <div class="panel-body">
 {# form开始 #}
 <form class="form-horizontal" action="" method="post" novalidate>
 {% csrf_token %}
 <div class="form-group">
 <label class="col-md-2 control-label"
 for="{{ form.title.id_for_label }}">{{ form.title.label }}</label>
 <div class="col-md-10">
 {{ form.title }}
 </div>
 </div>
 <div class="form-group">
 <label class="col-md-2 control-label"
 for="{{ form.price.id_for_label }}">{{ form.price.label }}</label>
 <div class="col-md-10">
 {{ form.price }}
 </div>
 </div>
 <div class="form-group">
 <label class="col-md-2 control-label"
 for="{{ form.publish_date.id_for_label }}">{{ form.publish_date.label }}</label>
 <div class="col-md-10">
 {{ form.publish_date }}
 </div>
 </div>
 <div class="form-group">
 <label class="col-md-2 control-label"
 for="{{ form.publisher.id_for_label }}">{{ form.publisher.label }}</label>
 <div class="col-md-10">
 {{ form.publisher }}
 </div>
 </div>
 <div class="form-group">
 <label class="col-md-2 control-label"
 for="{{ form.authors.id_for_label }}">{{ form.authors.label }}</label>
 <div class="col-md-10">
 {{ form.authors }}
 </div>
 </div>
 <div class="form-group">
 <div class="col-md-offset-2 col-md-10">
 <button type="submit" class="btn btn-success">提交</button>
 <a class="btn btn-warning pull-right" href="/book/" rel="external nofollow" >取消</a>
 </div>
 </div>
 </form>
 {# form结束 #}
 </div>
 {# panel-body结束 #}
 </div>
 {# panel结束 #}
 </div>
</div>
</body>
</html>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。