Django---ModelForm详解

示例:

from django.db import models
from django.forms import ModelForm

TITLE_CHOICES = (
    ('MR', 'Mr.'),
    ('MRS', 'Mrs.'),
    ('MS', 'Ms.'),
)

class Author(models.Model):
    name = models.CharField(max_length=100)
    title = models.CharField(max_length=3, choices=TITLE_CHOICES)
    birth_date = models.DateField(blank=True, null=True)

    def __str__(self):              # __unicode__ on Python 2
        return self.name

class Book(models.Model):
    name = models.CharField(max_length=100)
    authors = models.ManyToManyField(Author)

class AuthorForm(ModelForm):
    class Meta:
        model = Author #绑定数据库表
        fields = ['name', 'title', 'birth_date'] #显示的字段(‘__all__’)

class BookForm(ModelForm):
    class Meta:
        model = Book
        fields = ['name', 'authors']

选择用到的字段:

  fields = [] 或 ‘__all__’

  exclude = [ ]

save()方法:

每个ModelForm还具有一个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。

模型表单的子类可以用关键字参数instance 接收一个已经存在的模型实例;如果提供,save() 将更新这个实例。

>>> from myapp.models import Article
>>> from myapp.forms import ArticleForm

# Create a form instance from POST data.
>>> f = ArticleForm(request.POST)
# 创建新对象
>>> new_article = f.save()

# Create a form to edit an existing Article, but use
# POST data to populate the form.
#更新该对象
>>> a = Article.objects.get(pk=1)
>>> f = ArticleForm(request.POST, instance=a)
>>> f.save()

重写(覆盖)默认的字段:

from django.forms import ModelForm, Textarea
from myapp.models import Author

class AuthorForm(ModelForm):
    class Meta:
        model = Author
        fields = ('name', 'title', 'birth_date')
        widgets = {
            'name': Textarea(attrs={'cols': 80, 'rows': 20}),
        }

覆盖字段:

from django.forms import ModelForm
from myapp.models import Article
from django.forms import fields

class ArticleForm(ModelForm):
    slug = fields.ChoiceField()

    class Meta:
        model = Article
        fields = ['pub_date', 'headline', 'content', 'reporter', 'slug']

提供初始值:

>>> article = Article.objects.get(pk=1)
>>> article.headline
'My headline'
>>> form = ArticleForm(initial={'headline': 'Initial headline'}, instance=article)
>>> form['headline'].value()
'Initial headline'

class XXXModelForm(ModelForm)

    a.  class Meta:
            model,                           # 对应Model的
            fields=None,                     # 字段
            exclude=None,                    # 排除字段
            labels=None,                     # 提示信息
            help_texts=None,                 # 帮助提示信息
            widgets=None,                    # 自定义插件
            error_messages=None,             # 自定义错误信息(整体错误信息from django.core.exceptions import NON_FIELD_ERRORS)
            field_classes=None               # 自定义字段类 (也可以自定义字段)
            localized_fields=('birth_date',) # 本地化,如:根据不同时区显示数据
            如:
                数据库中
                    2016-12-27 04:10:57
                setting中的配置
                    TIME_ZONE = 'Asia/Shanghai'
                    USE_TZ = True
                则显示:
                    2016-12-27 12:10:57
    b. 验证执行过程
        is_valid -> full_clean -> 钩子 -> 整体错误
 
    c. 字典字段验证
        def clean_字段名(self):
            # 可以抛出异常
            # from django.core.exceptions import ValidationError
            return "新值"
    d. 用于验证
        model_form_obj = XXOOModelForm()
        model_form_obj.is_valid()
        model_form_obj.errors.as_json()
        model_form_obj.clean()
        model_form_obj.cleaned_data
    e. 用于创建
        model_form_obj = XXOOModelForm(request.POST)
        #### 页面显示,并提交 #####
        # 默认保存多对多
            obj = form.save(commit=True)
        # 不做任何操作,内部定义 save_m2m(用于保存多对多)
            obj = form.save(commit=False)
            obj.save()      # 保存单表信息
            obj.save_m2m()  # 保存关联多对多信息
 
    f. 用于更新和初始化
        obj = model.tb.objects.get(id=1)
        model_form_obj = XXOOModelForm(request.POST,instance=obj)
        ...
 
        PS: 单纯初始化
            model_form_obj = XXOOModelForm(initial={...})
 
原文地址:https://www.cnblogs.com/mona524/p/7716245.html