modelform組件以及ChoiceField屬性

一. Forms組件補充

1.__init__()

若是繼承forms.Form的類中的每個字段,或者大部分字段都作了相同的約束,能夠將該約束放到__init__中編寫

實例:每個字段都須要添加form-control類名

1 class BookForm(forms.Form):
2     title = forms.CharField(max_length=32)
3     pub_date = forms.DateField()
4     price = forms.DecimalField(max_digits=8, decimal_places=2)
5 
6     def __init__(self,*args,**kwargs):
7         super().__init__(*args,**kwargs)
8         for field in self.fields.values():
9             field.widget.attrs.update({"class":"form-control"})

2.ChoiceField屬性,下拉菜單(元組套元組的形式)

(1)choices做用:在數據庫中用元組的第一項做爲存儲的值,在顯示時,將元組的第二項做爲顯示的內容,便於前端使用下拉框

例:

1 class Book(models.Model):
2     id=models.AutoField(primary_key=True)
3     title=models.CharField(max_length=32)
4     gender=models.IntegerField(choices=((1,"男"),(2,"女")),default=1)

(2)與get_gender_display()方法同時使用,用來獲取元組第二項的內容

(3)在forms組件中渲染時,只需將類型改變成ChoiceField()

例:

1 class BookForm(forms.Form):
2     title = forms.CharField(label="書名",max_length=32)
3     pub_date = forms.DateField(label="出版社")
4     price = forms.DecimalField(label="價格",max_digits=8, decimal_places=2)
5     gender=forms.ChoiceField(choices=((1,"男"),(2,"女")))

(4) Choices的問題:小元組的內容是固定的,沒法隨着數據庫的更改二更改,不靈活

3.ModelChoiceField屬性

做用:幫助渲染前端頁面的下拉框

優點:ModelChoiceField能夠接收queryset屬性的參數,內容能夠隨着數據庫的更改而更改

例:

1 class BookForm(forms.Form):
2     title = forms.CharField(label="書名",max_length=32)
3     gender=forms.ChoiceField(choices=((1,"男"),(2,"女")))
4     publish=forms.ModelChoiceField(queryset=Publish.objects.all())

4.ModelMultipleChoiceField屬性

做用:幫助前端渲染頁面的多選框,內容也能隨着數據庫的改變而改變

例:

1 class BookForm(forms.Form):
2     gender=forms.ChoiceField(choices=((1,"男"),(2,"女")))
3     publish=forms.ModelChoiceField(queryset=Publish.objects.all())
4     author=forms.ModelMultipleChoiceField(queryset=Author.objects.all())

二. modelForm組件

1.做用:

　　正常狀況下的model和form是沒有關係的,全部forms組件必須咱們本身編寫,可是ModelForm能夠與model之間造成對應關係,這樣就免去了咱們本身寫model

2.語法:

(1)須要先引入forms組件的model類:from django.forms import ModelForm

(2)編寫ModelForm類:

1 class BookModelForm(forms.ModelForm):
2     class Meta:
3         model=Book  #與之關聯的模型類
4         # fields="__all__"  #能夠渲染全部字段
5         fields=["title","price"]  #能夠渲染部分字段
6 
7         exclide=[「title」]  #能夠渲染除某些字段外的全部字段

(3)爲公共字段或大多數字段添加內容,批量處理(添加__init__方法)

Input標籤的樣式屬性:

1 def __init__(self,*args,**kwargs):
2     super().__init__(*args,**kwargs)
3     for field in self.fields.values():
4         field.widget.attrs.update({"class":"form-control"})

將錯誤轉換成中文:

1 def __init__(self,*args,**kwargs):
2     super().__init__(*args,**kwargs)
3     for field in self.fields.values():
4         field.error_messages={"required":"不能爲空"}

(4)爲單個字段添加內容(當每一個字段的內容不一樣時)

 1 Labels方法:
 2 
 3 class BookModelForm(forms.ModelForm):
 4         class Meta:
 5             model=Book
 6             fields="__all__"
 7             labels={"title":"書籍名稱","price":"價格"}
 8 
 9 error_messages方法:
10 
11 class BookModelForm(forms.ModelForm):
12     class Meta:
13         model=Book
14         fields="__all__"
15         error_messages={"title":{"required":"書籍名稱不能爲空"}}
16 
17 widgets字段:
18 
19 先引入:from django.forms import widgets as Fwidgets
20 
21 class BookModelForm(forms.ModelForm):
22     class Meta:
23         model=Book
24         fields="__all__"
25         widgets = {
26             'pub_date': Fwidgets.Input(attrs={'type': 'date'})
27         }

3.forms組件有的接口,modelform也有,如is_valid,clean_data,errors

除了forms組件有的接口外,modelform還有save方法

Save方法會自動將乾淨的數據添加到表中,含有一對一,一對多,多對多的字段和表也會被處理好

4.編輯頁面,默認value值得作法:

(1)取到待編輯的model對象

例:book_obj=Book.objects.fillter(id=1).first()

(2)將model對象傳入modelform

例:form=BookModelForm(request.POST,instance=book_obj)

獲得的form就是待前端頁面渲染的對象

結果:若是對ModelForm傳了instance就至關於更新操做,沒傳instance,就至關於建立操做

三.include

做用:當某一段代碼被重複利用的次數不少時,能夠將其寫到一個文件中,其餘地方引用便可,減小代碼的冗餘性

例:在form.html中

 1 <form action="" method="post" novalidate>
 2     {% csrf_token %}
 3       {% for field in form %}
 4             <div class="form-group">
 5                  <label for="title">{{ field.label }}</label>
 6                  {{ field }}
 7                  <span>{{ field.errors.0 }}</span>
 8             </div>
 9      {% endfor %}
10     <input type="submit" value="提交" class="btn btn-default pull-right">
11 </form>

在增長書籍頁面中:

 1 <!DOCTYPE html>
 2 <html lang="zh-CN">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>Title</title>
 6     <meta name="viewport" content="width=device-width, initial-scale=1">
 7      <!-- 最新版本的 Bootstrap 核心 CSS 文件 -->
 8     <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css"
 9           integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
10 
11 </head>
12 <body>
13 <h3>添加書籍</h3>
14 <div class="container">
15     <div class="row">
16         <div class="col-md-6 col-md-offset-3">
17            {% include 'form.html' %}  #表明將form.html中的代碼放到這裏
18         </div>
19     </div>
20 </div>
21 </body>
22 </html>

四.ModelForm的使用模板(作添加和編輯頁面)

1.在models.py中:正常寫模型表

 1   class Book(models.Model):
 2      nid=models.AutoField(primary_key=True)
 3      title=models.CharField(max_length=32)
 4      price=models.DecimalField(max_digits=8,decimal_places=2) # 999999.99
 5      pub_date=models.DateTimeField()  # "2012-12-12"
 6      publish=models.ForeignKey(to="Publish",on_delete=models.CASCADE) 
 7      authors=models.ManyToManyField(to="Author")
 8 
 9 
10    def __str__(self):
11        return self.title

2.在form.py中:構建ModelForm

 1 from django.forms import widgets as Fwidgets
 2 class BookModelForm(forms.ModelForm):
 3     class Meta:
 4         model=Book
 5         fields="__all__"
 6         labels={"title":"書籍名稱","price":"價格"}
 7         widgets = {
 8             'pub_date': Fwidgets.Input(attrs={'type': 'date'})
 9         }
10     def __init__(self,*args,**kwargs):
11         super().__init__(*args,**kwargs)
12         for field in self.fields.values():
13             field.widget.attrs.update({"class":"form-control"})
14             field.error_messages={"required":"不能爲空"}
15 
16 等同於寫了如下代碼:
17 
18 class BookForm(forms.Form):
19 
20 
21 title=forms.CharField(max_length=32)
22 price=forms.IntegerField()
23 pub_date=forms.DateField(widget=widgets.TextInput(attrs={"type":"date"}))
24 #publish=forms.ChoiceField(choices=[(1,"AAA"),(2,"BBB")])
25 publish=forms.ModelChoiceField(queryset=Publish.objects.all())
26 authors=forms.ModelMultipleChoiceField(queryset=Author.objects.all())

3.添加邏輯

 1 def add(request):
 2 
 3 if GET請求:
 4 
 5 form=BookModelForm()
 6 
 7 return render(request,{「form」:form})
 8 
 9 else POST請求:
10 
11 form=BookModelForm(request.POST)
12 
13 if form.is_valid():
14 
15 form.save()
16 
17 return render(「/」)
18 
19 else:
20 
21 return render(request,{「form」:form})

4.編輯邏輯

 1 def edit(request,id):
 2 
 3 edit_obj=Book.objects.get(pk=id)
 4 
 5 if GET請求:
 6 
 7 form=BookModelForm(instance=edit_obj)
 8 
 9 return render(request,{「form」:form})
10 
11 else POST請求:
12 
13 form=BookModelForm(request.POST,instance=edit_obj)
14 
15 if form.is_valid():
16 
17 form.save()
18 
19 return rediecr(「/」)
20 
21 else:
22 
23 return render(request,{「form」:form})

5.登陸和編輯共同的渲染頁面

 1 <form action="" method="post" novalidate>
 2 
 3 
 4 {% csrf_token %}
 5   {% for field in form %}
 6       <div class="form-group">
 7           <label for="title">{{ field.label }}</label>
 8           {{ field }}
 9           <span>{{ field.errors.0 }}</span>
10       </div>
11  {% endfor %}
12 <input type="submit" value="提交" class="btn btn-default pull-right">
13 
14 
15 </form>