Django ModelForm组件使用方法详解

框架(架构)  /  管理员 发布于 7年前   221

一、创建ModelForm

from django.forms import ModelFormfrom appxx import modelsfrom 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,redirectfrom appxx import modelsfrom appxx import formsdef 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,redirectfrom appxx import modelsfrom appxx import formsdef 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 urlfrom django.contrib import adminfrom appxx import viewsurlpatterns = [  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,redirectfrom appxx import modelsfrom appxx import formsdef 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 modelsclass 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.titleclass Publisher(models.Model):  id = models.AutoField(primary_key=True)  name = models.CharField(max_length=32)  def __str__(self):    return self.nameclass 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 ModelFormfrom appxx import modelsfrom django.forms import widgets as wdtclass 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="https: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="https: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="https:book/edit/{{ book.pk }}/" rel="external nofollow" >编辑</a></span>  <span><a class="btn btn-danger" href="https:/article/">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="https: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="https: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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