96django_modelform-创新互联

目录

ModelForm..1

Model field与Form field：...1

ModelForm save()方法：...4

ModelForm Meta：...5

ModelForm自定义验证：...5

ModelForm initial and  instance：...6

ModelForm

结合了form和model，将model的field类型映射成form的field类型，复用了model的验证，还实现了存储数据库的简单方法，写更简洁的代码；

django提供一个辅助类（class Meta），使之可从Model创建Form；

生成的Form类中将具有和指定的模型字段对应的表单字段，顺序为fields属性中指定的顺序；

Model field与Form field：

每个模型字段有一个对应的默认表单字段，如模型中的ManyToManyField对应表单中的ModelMultipleChoiceField，ForeignKey<-->ModelChoiceField；

例：

mysite/books/models.py

TITLE_CHOICE = (

('MR', 'Mr.'),

('MRS', 'Mrs'),

('MS', 'Ms.'),

)

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)

def __str__(self):

return self.name

class Book(models.Model):

name = models.CharField(max_length=100)

authors = models.ManyToManyField(Author)

mysite/books/forms.py

from django import forms

from django.forms import ModelForm

from .models import Author, Book

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，建议显式的设置，否则有安全问题

class BookForm(ModelForm):

class Meta:

model = Book

fields = ['name', 'authors']

# 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())

注：

模型字段blank=True，表单字段require=False；

模型字段verbose_name（首字段大写the first character capitalized），表单字段label；

模型字段help_text，表单字段help_text；

模型字段choices，表单字段widget=forms.Select(choices=TITLE_CHOICE)，choices从模型中来，选项通常会包含空选项，且默认会选择，如果字段是必选的，它会强制用户选择一个选项，如果模型字段的default且有一个显示default值，将不会包含空选项（初始值即blank=False）；

ModelForm save()方法：

这个方法根据表单绑定的数据创建并保存数据库对象；

save()接受关键字参数commit，book=save(commit=False)时：

1将返回一个还没有保存到数据库的对象，这种情况下，要调用模型实例的form.save()，

2在多对多关系时指定commit=False，django不会立即为多对多有关系保存表单数据（只有实例在数据库中存在时才可保存实例的多对多关系），要手动调用save_m2m()来保存多对多的表单数据

save_m2m()仅在save(commit=False)时才用到；

>>> 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()，后续用返回的对象

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

>>> form.is_valid()

True

>>> form.save()   #author=form.save()

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

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

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

>>> form.is_valid()

True

>>> form.save()   #book=form.save()

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

>>> form.is_valid()

True

>>> form.save()

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

>>> form

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

>>> book

>>> book.name = 'react book'

>>> book.save()

>>> form.save_m2m()

>>> book.name

'react book'

ModelForm Meta：

mysite/publish/forms.py

class AuthorForm(ModelForm):

class Meta:

model = Author

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

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."}}

ModelForm自定义验证：

mysite/publish/forms.py

class AuthorForm(ModelForm):

class Meta:

model = Author

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

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."}}

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))

def clean_name(self):   #clean_

name = self.cleaned_data['name']

if len(name) < 30:

raise ValidationError('length must more than 30')

return name

ModelForm initial and instance：

提供初始值；

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

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})

def update(request, publish_id):

author = get_object_or_404(Author, id=publish_id)

if request.method == 'POST':

form = AuthorForm(request.POST, instance=author)   #更新时要加instance，否则认为是新创建，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})

mysite/publish/models.py

from django.db import models

TITLE_CHOICE = (

('MR', 'Mr.'),

('MRS', 'Mrs'),

('MS', 'Ms.'),

)

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)

def __str__(self):

return self.name

class Book(models.Model):

name = models.CharField(max_length=100)

authors = models.ManyToManyField(Author)

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