Django ModelForm组件使用方法详解
人气:0一、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>
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