96django_modelform

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目錄

ModelForm.. 1

Model field與Form field：... 1

ModelForm save()方法：... 4

ModelForm Meta：... 5

ModelForm自定義驗證：... 5

ModelForm initial and ?instance：... 6

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ModelForm

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結合了form和model，將model的field類型映射成form的field類型，復用了model的驗證，還實現了存儲數據庫的簡單方法，寫更簡潔的代碼；

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django提供一個輔助類（class Meta），使之可從Model創建Form；

生成的Form類中將具有和指定的模型字段對應的表單字段，順序為fields屬性中指定的順序；

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Model field與Form field：

每個模型字段有一個對應的默認表單字段，如模型中的ManyToManyField對應表單中的ModelMultipleChoiceField，ForeignKey<-->ModelChoiceField；

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例：

mysite/books/models.py

TITLE_CHOICE = (

??? ('MR', 'Mr.'),

??? ('MRS', 'Mrs'),

??? ('MS', 'Ms.'),

)

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class Author(models.Model):

??? name = models.CharField(max_length=100)

??? title = models.CharField(max_length=3, choice=TITLE_CHOICE)

??? birth_date = models.DateField(blank=True, null=True)

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??? def __str__(self):

??????? return self.name

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class Book(models.Model):

??? name = models.CharField(max_length=100)

??? authors = models.ManyToManyField(Author)

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mysite/books/forms.py

from django import forms

from django.forms import ModelForm

from .models import Author, Book

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class AuthorForm(ModelForm):

??? class Meta:

??????? model = Author

??????? fields = ['name', 'title', 'birth_date']?? #使用model的全部字段，用field = '__all__'，另exclude = ('birth_date')排除的字段列表，建議顯式的設置，否則有安全問題

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class BookForm(ModelForm):

??? class Meta:

??????? model = Book

??????? fields = ['name', 'authors']

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# from .models import TITLE_CHOICE

# class AuthorForm(forms.Form):

#???? name = forms.CharField(max_length=100)

#???? title = forms.CharField(max_length=3, widget=forms.Select(choices=TITLE_CHOICE))

#???? birth_date = forms.DateField(required=False)

#

# class BookFrom(forms.Form):

#???? name = forms.CharField(max_length=100)

#???? authors = forms.ModelMultipleChoiceField(queryset=Author.objects.all())

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注：

模型字段blank=True，表單字段require=False；

模型字段verbose_name（首字段大寫the first character capitalized），表單字段label；

模型字段help_text，表單字段help_text；

模型字段choices，表單字段widget=forms.Select(choices=TITLE_CHOICE)，choices從模型中來，選項通常會包含空選項，且默認會選擇，如果字段是必選的，它會強制用戶選擇一個選項，如果模型字段的default且有一個顯示default值，將不會包含空選項（初始值即blank=False）；

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ModelForm save()方法：

這個方法根據表單綁定的數據創建并保存數據庫對象；

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save()接受關鍵字參數commit，book=save(commit=False)時：

1將返回一個還沒有保存到數據庫的對象，這種情況下，要調用模型實例的form.save()，

2在多對多關系時指定commit=False，django不會立即為多對多有關系保存表單數據（只有實例在數據庫中存在時才可保存實例的多對多關系），要手動調用save_m2m()來保存多對多的表單數據

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save_m2m()僅在save(commit=False)時才用到；

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>>> from publish.models import Author,Book

>>> from publish.forms import AuthorForm,BookForm

>>> form = AuthorForm({'name':'jowin','title':'MR'})

>>> form.is_valid()

True

>>> form.is_bound

True

>>> form.save()?? #author=form.save()，后續用返回的對象

<Author: jowin>

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>>> form = AuthorForm({'name':'mage','title':'MR'})

>>> form.is_valid()

True

>>> form.save()?? #author=form.save()

<Author: mage>

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>>> authors = Author.objects.all()

>>> authors_id = [author.id for author in authors]

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>>> form = BookForm({'name':'django book','authors':authors_id})

>>> form.is_valid()

True

>>> form.save()?? #book=form.save()

<Book: Book object>

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>>> form = BookForm({'name':'py book','authors':authors_id})

>>> form.is_valid()

True

>>> form.save()

<Book: Book object>

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>>> form = BookForm({'name':'js book','authors':authors_id})

>>> form

<BookForm bound=True, valid=Unknown, fields=(name;authors)>

>>> book = form.save(commit=False)

>>> book

<Book: Book object>

>>> book.name = 'react book'

>>> book.save()

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>>> form.save_m2m()

>>> book.name

'react book'

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ModelForm Meta：

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mysite/publish/forms.py

class AuthorForm(ModelForm):

??? class Meta:

??????? model = Author

??????? fields = ['name', 'title', 'birth_date']?? #fields = '__all__';exclude = ('birth_date')

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??????? labels = {'name': 'Writer'}

??????? widgets = {'name': Textarea(attrs={'cols': 80, 'rows': 20})}?? #forms.Textarea()

??????? help_texts = {'name': 'Some useful help text'}

??????? error_messages = {'name': {'max_length': "This writer's name is too long."}}

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ModelForm自定義驗證：

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mysite/publish/forms.py

class AuthorForm(ModelForm):

??? class Meta:

??????? model = Author

??????? fields = ['name', 'title', 'birth_date']?? #fields = '__all__';exclude = ('birth_date')

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??????? labels = {'name': 'Writer'}

??????? widgets = {'name': Textarea(attrs={'cols': 80, 'rows': 20})}

??????? help_texts = {'name': 'Some useful help text'}

??????? error_messages = {'name': {'max_length': "This writer's name is too long."}}

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??????? def clean(self):

??????????? cleaned_data = super(AuthorForm, self).clean()

??????????? name = cleaned_data.get('name')

??????????? title = cleaned_data.get('title')

??????????? if len(name) < 40 and title == 'MR':

??????????????? raise ValidationError('Field: {} and {} is error'.format(name, title))

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??????? def clean_name(self):?? #clean_<field-name>

??????????? name = self.cleaned_data['name']

??????????? if len(name) < 30:

??????????????? raise ValidationError('length must more than 30')

??????????? return name

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ModelForm initial and instance：

提供初始值；

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mysite/publish/views.py?? #view中使用modelform

from django.shortcuts import render, get_object_or_404

from django.http import HttpResponse

from .forms import AuthorForm

from .models import Author

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def index(request):

??? if request.method == 'POST':

???? ???form = AuthorForm(request.POST)

??????? if form.is_valid():

??????????? publish = form.save()

??????????? return HttpResponse('ok')

??? else:

??????? form = AuthorForm()

??? return render(request, 'publish/publish.html', {'form': form})

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def update(request, publish_id):

??? author = get_object_or_404(Author, id=publish_id)

??? if request.method == 'POST':

??????? form = AuthorForm(request.POST, instance=author)?? #更新時要加instance，否則認為是新創建，也可form=AuthorForm(request.POST,initial={'name':'test'})

??????? if form.is_valid():

??????????? author = form.save()

??????????? return HttpResponse('add succeed')

??? form = AuthorForm(instance=author)?? #initial={'name':'test'}

??? return render(request, 'publish/publish.html', {'form': form})

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mysite/publish/models.py

from django.db import models

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TITLE_CHOICE = (

??? ('MR', 'Mr.'),

??? ('MRS', 'Mrs'),

??? ('MS', 'Ms.'),

)

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class Author(models.Model):

??? name = models.CharField(max_length=100)

??? title = models.CharField(max_length=3, choices=TITLE_CHOICE)

??? birth_date = models.DateField(blank=True, null=True)

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??? def __str__(self):

??????? return self.name

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class Book(models.Model):

??? name = models.CharField(max_length=100)

??? authors = models.ManyToManyField(Author)

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