Django之ModelForm

ModelForm：

 应用场景：
            - ModelForm - 中小型应用程序。因为ModelForm是依赖于models的
            - Form      - 大型应用程序  *

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={...})

            - 1. 类 
                  class Foo(ModelForm):
                    class Meta:
                        # model = models.Role
                        # fields = "__all__"
                        # fields = ['caption',]
                        # exclude = ['catpion']
                        model = models.UserType
                        fields = "__all__"

                        error_messages = {
                            'title':{'required':'名称不能为空','invalid':'格式错误'}
                        }
                        widgets = {
                            'title':wd.TextInput(attrs={'class':'c1'})
                        }
                
            - 2. 添加
                 GET:
                    form = Foo()
                 POST:
                    form = Foo(data=request.POST)
                    form.is_valid()
                    form.cleaned_data
                    form.erros
                    form.save()
            - 3. 修改
                 GET:
                    form = Foo(instance=obj)
                 
                 POST:
                    form = Foo(instance=obj,dat=request.POST)
                    ...
                    form.save()

使用

from django.shortcuts import render,HttpResponse
from app01 import models

from django import forms
from django.forms import fields as Ffields
from django.forms import widgets as Fwidgets
class UserInfoModelForm(forms.ModelForm):

    is_rmb = Ffields.CharField(widget=Fwidgets.CheckboxInput())  # 免登录Checkbox字段

    class Meta:
        model = models.UserInfo
        fields = '__all__'
        # fields =  ['username','email']
        # exclude = ['username']
        labels = {
            'username': '用户名',
            'email': '邮箱',
        }
        help_texts = {
            'username': '...'
        }
        widgets = {
            'username': Fwidgets.Textarea(attrs={'class': 'c1'})
        }
        error_messages = {
            '__all__':{            # 定义整体的错误信息

            },
            'email': {
                'required': '邮箱不能为空',
                'invalid': '邮箱格式错误..',
            }
        }
        field_classes = {
            # 'email': Ffields.URLField        # 和model中定义字段不同，这里只能填写类，可以覆盖model中的字段属性
        }

        # localized_fields=('ctime',)

    def clean_username(self):
        old = self.cleaned_data['username']
        return old

class UserInfoForm(forms.Form):
    username = Ffields.CharField(max_length=32)
    email = Ffields.EmailField()
    user_type = Ffields.ChoiceField(
        choices=models.UserType.objects.values_list('id','caption')
    )

    def __init__(self, *args, **kwargs):
        super(UserInfoForm,self).__init__(*args, **kwargs)
        self.fields['user_type'].choices = models.UserType.objects.values_list('id','caption')
'''
源码截取： 
    def save(self, commit=True):
        if commit:
            # If committing, save the instance and the m2m data immediately.
            self.instance.save()
            self._save_m2m()
        else:
            # If not committing, add a method to the form to allow deferred
            # saving of m2m data.
            self.save_m2m = self._save_m2m
'''

def index(request):
    if request.method == "GET":
        obj = UserInfoModelForm()
        return render(request,'index.html',{'obj': obj})
    elif request.method == "POST":
        obj = UserInfoModelForm(request.POST)
        if obj.is_valid():
            # obj.save()
            instance = obj.save(False)            # self.instance 当前model对象
            instance.save()                        # 仅保存当前类对应的表,相当于源码中if条件的self.instance.save()
            obj.save_m2m()                        # 相当于源码中if条件的self._save_m2m()，else分支中做了赋值self.save_m2m = self._save_m2m


        # print(obj.is_valid())
        # print(obj.cleaned_data)
        # print(obj.errors.as_json())
        return render(request,'index.html',{'obj': obj})


def user_list(request):
    li = models.UserInfo.objects.all().select_related('user_type')
    return render(request,'user_list.html',{'li': li})

def user_edit(request, nid):
    # 获取当前id对象的用户信息
    
    if request.method == "GET":
        user_obj = models.UserInfo.objects.filter(id=nid).first()
        mf = UserInfoModelForm(instance=user_obj)            # 显示用户已经存在数据
        return render(request,'user_edit.html',{'mf': mf, 'nid': nid})
    elif request.method == 'POST':
        user_obj = models.UserInfo.objects.filter(id=nid).first()
        mf = UserInfoModelForm(request.POST,instance=user_obj)
        if mf.is_valid():

            mf.save()
        else:
            print(mf.errors.as_json())
        return render(request,'user_edit.html',{'mf': mf, 'nid': nid})
        
# modelform小结        
    1. 生成HTML标签：class Meta: ...
    2. 显示用户已经存在数据 ：mf = xxxModelForm(instance=ModelObj)
    3. 额外的标签， is_rmb = Ffields.CharField(widget=Fwidgets.CheckboxInput())  #  7天免登录Checkbox字段
    4. 各种验证 is_valid() -> 各种钩子...  # 方法和Form中的钩子完全一样
    5.     mf.save()
        # 或
        instance = mf.save(False)
        instance.save()
        mf.save_m2m()