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Django ModelForm組件使用方法詳解

 更新時(shí)間：2019年07月23日 11:13:52   作者：little_pd  
這篇文章主要介紹了Django ModelForm組件使用方法詳解,文中通過(guò)示例代碼介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值,需要的朋友可以參考下

一、創(chuàng)建ModelForm

from django.forms import ModelForm
from appxx import models
from django.forms import widgets as wdt # 因?yàn)橹孛?，所以起個(gè)別名
#定義一個(gè)類，比如BookForm，這個(gè)類要繼承ModelForm，在這個(gè)類中再寫一個(gè)原類Meta（規(guī)定寫法，注意首字母是大寫的）
#在這個(gè)原類中，有以下屬性（部分）：
class BookForm(ModelForm):
  class Meta:
    model = models.Book # 對(duì)應(yīng)的Model中的類
    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": "書名不能為空"},
      "price": {"required": "售價(jià)不能為空"},
    }
    # widgets用法，比如把輸入用戶名的input框給為Textarea
    widgets = {
      "name": wdt.Textarea(attrs={"class": "c1"}) # 還可以自定義屬性
    }
    #labels，自定義在前端顯示的名字
    labels= {
      "title": "書名",
      "price": "售價(jià)",
    }

然后在 url 對(duì)應(yīng)的視圖函數(shù)中實(shí)例化這個(gè)類，把這個(gè)對(duì)象傳給前端：

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

然后在前端像Form組件那樣渲染頁(yè)面

二、添加數(shù)據(jù)

保存數(shù)據(jù)的時(shí)候，不用挨個(gè)取數(shù)據(jù)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、編輯數(shù)據(jù)

如果不使用 ModelForm，編輯的時(shí)候得顯示之前的數(shù)據(jù)，還得挨個(gè)取一遍值；如果使用 ModelForm，只需要加一個(gè)instance=obj（obj是要修改的數(shù)據(jù)庫(kù)的一條數(shù)據(jù)的對(duì)象）就可以得到同樣的效果。

保存的時(shí)候要注意，一定要注意有這個(gè)對(duì)象（instance=obj），否則不知道更新哪一個(gè)數(shù)據(jù)。

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})

總結(jié)： 從上邊可以看到 ModelForm 用起來(lái)是非常方便的，比如增加修改之類的操作。但是也帶來(lái)額外不好的地方，model和form之間耦合了。如果不耦合的話，form.save()方法也無(wú)法直接提交保存。 但是耦合的話使用場(chǎng)景通常局限用于小程序，寫大程序就最好不用了。

四、完整示例代碼

項(xiàng)目結(jié)構(gòu)

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": "書名",
      "price": "售價(jià)",
      "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": "書名不能為空"},
      "price": {"required": "售價(jià)不能為空"},
      "publish_date": {"required": "出版日期不能為空"},
      "publisher": {"required": "出版社不能為空"},
      "authors": {"required": "作者不能為空"},
    }

book.html

<!DOCTYPE html>
<html lang="zh-cn">
<head>
  <meta charset="UTF-8">
  <title>展示書籍</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>序號(hào)</th>
          <th>書名</th>
          <th>售價(jià)</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" >編輯</a></span>
              <span><a class="btn btn-danger" href="">刪除</a></span>
            </td>
          </tr>
        {% endfor %}
        </tbody>
      </table>
    </div>
  </div>
</div>
</body>
</html>

add_book.html和edit_book.html（兩個(gè)頁(yè)面代碼一樣）

<!DOCTYPE html>
<html lang="zh-cn">
<head>
  <meta charset="UTF-8">
  <title>添加書籍</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開(kāi)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">添加書籍</h3>
      </div>
      {# panel-body開(kāi)始 #}
      <div class="panel-body">
        {# form開(kāi)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結(jié)束 #}
      </div>
      {# panel-body結(jié)束 #}
    </div>
    {# panel結(jié)束 #}
  </div>
</div>
</body>
</html>

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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