使用form组件对图书管理系统进行改进

会了form组建之后，我们可以把之前的图书管理系统使用form加上字段验证

我们只需要对views中的添加和修改逻辑进行修改 再添加form验证

• form组件只能对添加新字段进行验证 不能对修改字段进行验证
  • 因为form组件不涉及读取数据 只是作为验证 修改字段需要携带value数据
• views.py 部分代码展示

  from django import forms
  
  
  class BookFrom(forms.Form):
      title = forms.CharField(
          label="书名",
          max_length=32,
      )
      publishDate = forms.DateField(
          label="出版日期",
          widget=forms.widgets.TextInput(attrs={"type": "date"})
      )
      price = forms.DecimalField(
          label="价格",
          max_digits=5,
          decimal_places=2
      )
  
      # 一对多关系 方案一 写死了
      '''
      # publishs = forms.ForeignKey(to="Publish")
      publishs = forms.ChoiceField(
          label="出版社",
          choices=[
              (1, "滑稽出版社"),
              (2, "人民出版社"),
              (3, "垃圾出版社"),
          ],
          widget=forms.widgets.Select()
      )
      '''
      # 写活了
      publishs = forms.ModelChoiceField(
          label="出版社",
          queryset=models.Publish.objects.all()  # 获取一个queryset对象直接拿来生成choices使用
      )
  
      # 多对多关系 方案一
      '''
      # authors = forms.ManyToManyField(to='Author',) 
      authors = forms.MultipleChoiceField(
          label='作者',
          choices=[
              (1, "李二蛋"),
              (2, '王思丹'),
          ],
          widget=forms.widgets.SelectMultiple(),
      )
      '''
      authors = forms.ModelMultipleChoiceField(
          label='作者',
          queryset=models.Author.objects.all()
      )
  
      def __init__(self, *args, **kwargs):
          super().__init__(*args, **kwargs)
          for field in self.fields.values():  # self.fields 获取所有的字段
              field.widget.attrs.update(
                  {"class": "form-control"})  # 为获取到的字典对象添加属性
  
  # form只能对添加字段进行验证
  def addbooks(request):
      if request.method == 'GET':
          book_form_obj = BookFrom()
          return render(request, 'add_book.html', {
              'book_form_obj': book_form_obj,
          })
      if request.method == 'POST':
          print(request.POST)
          book_form_obj = BookFrom(request.POST)
          if book_form_obj.is_valid():
              print(book_form_obj.cleaned_data)
              # {'title': '屠龙勇士', 'publishDate': datetime.date(2020, 7, 10), 'price': Decimal('1'), 'publishs': <Publish: 人民出版社>, 'authors': <QuerySet [<Author: 李二蛋>]>}
              authors = book_form_obj.cleaned_data.pop("authors")
              new_book = models.Book.objects.create(
                  **book_form_obj.cleaned_data
              )
              new_book.authors.add(*authors) # 多对多可能传入多个做个 通过*打散传入多对多表
              return redirect('showbooks')
          else:
              return render(request, 'add_book.html', {
                  'book_form_obj': book_form_obj,
              })
      
      def editbooks(request, book_id):
          book_obj = models.Book.objects.filter(pk=book_id)
          if request.method == 'GET':
              
              # BookFrom({"key":value}) 接受的是这种值
              # 我们可以直接获取值发送给前端生成展示页面
              # 问题：多对多表和一对多表示queryset类型，key取值只能获取到字典
              # 无法实现(实现繁琐) 我们使用modelform组件实现
              book_form_obj = BookFrom(book_obj.values()[0])
      
              return render(request, 'edit_book.html', {
                  "book_form_obj":book_form_obj,
                  })

   

• add_book.html

  <h1>添加书籍</h1>
  
  <div class="container">
    <div class="row">
      <div class="col-md-8 col-md-offset-2">
        <form action="" method="post" novalidate>
          {% csrf_token %}
          <div class="form-group">
            <label for="{{ book_form_obj.title.id_for_label }}">{{ book_form_obj.title.label }}</label>
            {{ book_form_obj.title }}
            <span style="color: crimson;font-size: 12px;">{{ book_form_obj.title.errors.0 }}</span>
          </div>
          <div class="form-group">
            <label for="{{ book_form_obj.price.id_for_label }}">{{ book_form_obj.price.label }}</label>
            {{ book_form_obj.price }}
            <span style="color: crimson;font-size: 12px;">{{ book_form_obj.title.errors.0 }}</span>
          </div>
          <div class="form-group">
            <label for="{{ book_form_obj.publishDate.id_for_label }}">{{ book_form_obj.publishDate.label }}</label>
            {{ book_form_obj.publishDate }}
            <span style="color: crimson;font-size: 12px;">{{ book_form_obj.title.errors.0 }}</span>
          </div>  
          <div class="form-group">
            <label for="{{ book_form_obj.publishs.id_for_label }}">{{ book_form_obj.publishs.label }}</label>
            {{ book_form_obj.publishs }}
            <span style="color: crimson;font-size: 12px;">{{ book_form_obj.title.errors.0 }}</span>
          </div>  
          <div class="form-group">
            <label for="{{ book_form_obj.authors.id_for_label }}">{{ book_form_obj.authors.label }}</label>
            {{ book_form_obj.authors }}
            <span style="color: crimson;font-size: 12px;">{{ book_form_obj.title.errors.0 }}</span>
          </div>
          <button class="btn btn-success pull-right">提交</button>
        </form>
  
      </div>
    </div>
  
  </div>