day06 Django知识点

今日概要：

• Form和ModelForm组件【使用】【源码】
• 缓存【使用】
• ORM【使用】
• 其他：ContentTypes、Admin、权限、分页、信号等

1.Form和ModelForm组件

背景：某个公司后台管理项目。

• 垃圾

  def register(request):""" 用户注册 """# 1.获取提交数据mobile = request.POST.get("mobile")sms = request.POST.get("sms")name = request.POST.get("name")age = request.POST.get("age")email = request.POST.get("email")password = request.POST.get("password")# 2.校验判断（10行）# all([mobile,sms])# 正则表达式# 3.业务逻辑代码
  

• 框架（内置+第三方表单验证组件）

  <form method="post"><input type="text" name="mobile1" />{{form.mobile1}}<input type="text" name="sms" />{{form.sms}}<input type="submit" value="提交" />
  </form>
  

  class MyForm(Form):mobile1 = forms.CharField(reg="\d{11}", required=True)sms = forms.CharField(required=True)def register(request):""" 用户注册 """if request.method == "GET":# form = MyForm(instance={"mobile1":"18766666666","sms":"999"})form = MyForm()return render(request, "xxxxx.html",{"form":form})# 1.获取提交数据form = MyForm(request.POST)if form.is_valid():print(form.cleared_data)else:print(form.errors)# 3.业务逻辑代码return render(request, "xxxxx.html",{"form":form})
  

关于组件：表单验证、自动生成HTML标签、数据初始化（新建按钮、编辑按钮）、保持原来的数据。

1.1 初识Form组件

基于注册为例来进行测试。

详细见示例：1-form组件.zip

1.2 错误信息

1.3 展示所有的字段

对象和可迭代对象。

1.4 问题：关于样式

• 手动操作

  class RegisterForm(forms.Form):v1 = forms.CharField(label="手机号",required=True,# max_length=19,# min_length=6,initial="武沛齐",validators=[RegexValidator(r'^\d{11}$', "手机号格式错误"), ],widget=forms.TextInput(attrs={"class":"form-control"}) # <input type="text" class="form-control"/>)v2 = forms.CharField(label="备注",required=True,widget=forms.Textarea(attrs={"class":"form-control"}) # <textarea class="form-control"/></textarea>)............
  

  {% for field in form %}<p>{{ field.label }} {{ field }} {{ field.errors.0 }}  </p>
  {% endfor %}
  

• 自动操作（找到每个字段中的widget插件，再找到插件中的attrs属性，给他每个赋值**{“class”:“form-control”}**

  class RegisterForm(forms.Form):v1 = forms.CharField(...,widget=forms.TextInput)v2 = forms.CharField(...,widget=forms.TextInput(attrs={"v1":"123"}))def __init__(self,*args,**kwargs):super().__init__(self,*args,**kwargs)for name,field in self.fields.items():if name == "v1":continue if field.widget.attrs:field.widget.attrs.update({"class":"form-control"})else:field.widget.attrs = {"class":"form-control"}
  

  form = RegisterForm()                   # __init__
  form = RegisterForm(data=request.POST)  # __init__
  

1.5 问题：通用父类

class BootStrapForm(object):def __init__(self, *args, **kwargs):super().__init__(*args, **kwargs)for name, field in self.fields.items():field.widget.attrs = {"class": "form-control"}class LoginForm(BootStrapForm, forms.Form):user = forms.CharField(label="用户名", widget=forms.TextInput)pwd = forms.CharField(label="密码", widget=forms.TextInput)def login(request):form = LoginForm()return render(request, "login.html", {"form": form})

class BootStrapForm(forms.Form):def __init__(self, *args, **kwargs):# 不是找父类# 根据类的mro（继承关系），去找上个类# super().__init__(*args, **kwargs)for name, field in self.fields.items():field.widget.attrs = {"class": "form-control"}class LoginForm(BootStrapForm):user = forms.CharField(label="用户名", widget=forms.TextInput)pwd = forms.CharField(label="密码", widget=forms.TextInput)def login(request):form = LoginForm()return render(request, "login.html", {"form": form})

1.6 答疑

类的内部继承关系，是继续c3算法。

class A:passclass B:passclass C(B,A):pass# [<class '__main__.C'>, <class '__main__.B'>, <class '__main__.A'>, <class 'object'>]
print(C.mro())

老师 假如我们通过继承BootStrapForm实现批量给field对象添加{'class': 'form-control'}属性，那还能添加判断是否存在属性，若存在则更新；不存在再进行添加吗

1.7 ModelForm

• 使用Form

  • 创建Form类 + 定义字段

    class LoginForm(forms.Form):user = forms.CharField(label="用户名", widget=forms.TextInput)pwd = forms.CharField(label="密码", widget=forms.TextInput)
    

  • 视图

    def login(request):if request.method == "GET":form = LoginForm()return render(request, "login.html", {"form": form})form = LoginForm(data=request.POST)if not form.is_valid():# 校验失败return render(request, "login.html", {"form": form})print(form.cleaned_data)# ...return HttpRespon("OK")
    

  • 前端

    <form>{% for field in form %}<p>{{ field.label }} {{ field }} {{ field.errors.0 }}</p>{% endfor %}
    </form>
    

• 使用ModelForm

  • models.py

    class UserInfo(models.Model):name = models.CharField(verbose_name="用户名", max_length=32)age = models.IntegerField(verbose_name="年龄")email = models.CharField(verbose_name="邮箱", max_length=128)
    

  • 创建ModelForm

    class LoginForm(forms.ModelForm):mobile = forms.CharFiled(label="手机号")class Meta:model = models.UserInfofileds = ["name","age", "mobile"]
    

  • 视图使用

    def login(request):form = LoginModelForm()return render(request, "login.html", {"form": form})
    

  • 页面

    <form>{% for field in form %}<p>{{ field.label }} {{ field }} {{ field.errors.0 }}</p>{% endfor %}
    </form>
    

  注意：

  • 后续进行增伤改查是基于数据库Models中的某个表，推荐使用：ModelForm；

  • 如果要进行表单校验是与数据库的表无关直接使用Form。

1.8 ModelForm两个好的地方

1.8.1 初始化数据

• Form

  class LoginForm(BootStrapForm, forms.Form):user = forms.CharField(label="用户名", widget=forms.TextInput)pwd = forms.CharField(label="密码", widget=forms.TextInput)
  

  def login(request):form = LoginForm(initial={"user": "武沛齐", "pwd": "123"})return render(request, "login.html", {"form": form})
  

  

• ModelForm

  class LoginModelForm(BootStrapForm, forms.ModelForm):mobile = forms.CharField(label="手机号", widget=forms.TextInput)class Meta:model = models.UserInfofields = ["name", "age", "mobile"]widgets = {"age": forms.TextInput,}labels = {"age": "x2",}def clean_name(self):value = self.cleaned_data['name']# raise ValidationError("....")return value
  

  def login(request):user_object = models.UserInfo.objects.filter(id=1).first()form = LoginModelForm(instance=user_object, initial={"mobile": "武沛齐"})return render(request, "login.html", {"form": form})
  

1.8.2 新建数据

• Form组件

  def login(request):if request.method == "GET":form = LoginForm(initial={"user": "武沛齐", "pwd": "123"})return render(request, "login.html", {"form": form})form = LoginForm(data=request.POST)if not form.is_valid():return render(request, "login.html", {"form": form})# form.cleaned_data# 手动读取字典，保存至数据库# models.UserInfo.objects.create(name=form.cleaned_data['xx'], pwd=form.cleaned_data['yy'])return HttpResponse("成功")
  

• ModelForm组件

  def login(request):if request.method == "GET":form = LoginForm()return render(request, "login.html", {"form": form})form = LoginForm(data=request.POST)if not form.is_valid():return render(request, "login.html", {"form": form})form.save() # 自动将数据新增到数据库return HttpResponse("成功")
  

1.8.3 更新数据

• Form组件

  def login(request):if request.method == "GET":form = LoginForm(initial={"user": "武沛齐", "pwd": "123"})return render(request, "login.html", {"form": form})form = LoginForm(data=request.POST)if not form.is_valid():return render(request, "login.html", {"form": form})# form.cleaned_data# 手动读取字典，保存至数据库# models.UserInfo.objects.create(name=form.cleaned_data['xx'], pwd=form.cleaned_data['yy'])# models.UserInfo.objects.filter(id=1).update(name=form.cleaned_data['xx'], pwd=form.cleaned_data['y'])return HttpResponse("成功")
  

• ModelForm组件

  def login(request):if request.method == "GET":form = LoginModelForm()return render(request, "login.html", {"form": form})user_object = model.UserInfo.object.filter(id=1).first()form = LoginModelForm(data=request.POST, instance=user_object)if not form.is_valid():return render(request, "login.html", {"form": form})form.save() # 更新id=1return HttpResponse("成功")
  

1.9 案例

• 用户登录【Form】
• 用户管理：增改【ModelForm】

2.Form相关源码

2.1 前置知识点

1.模板渲染

def login(request):# 1.打开login2.html文件读取内容 + 参数进行“替换” => 渲染  ==> 得到被替换完的字符串# 2.将字符串封装HttpReponse对象中，等待给用户返回。return render(request, 'login2.html', {"v1": "wupeiqi"})

def render(request, template_name, context=None, content_type=None, status=None, using=None):content = loader.render_to_string(template_name, context, request, using=using)#    template = get_template(template_name, using=using)#    content = template.render(context, request)return HttpResponse(content, content_type, status)

from django.shortcuts import HttpResponse
from django.template.loader import get_templatedef v1(request):template = get_template("v1.html")text = template.render({"text": "张开"}, request)print(text)return HttpResponse("OK")

2.插件相关的类

class Widget(metaclass=MediaDefiningClass):def __init__(self, attrs=None):self.attrs = {} if attrs is None else attrs.copy()def render(self, name, value, attrs=None, renderer=None):# name="user" value="zhangkai"  attrs=None   self.attrs={'class': "c1", "id": "xx1"}context = self.get_context(name, value, attrs)return self._render(self.template_name, context, renderer)def get_context(self, name, value, attrs):return {"widget": {"name": name, # "user""value": self.format_value(value), # "zhangkai""attrs": self.build_attrs(self.attrs, attrs), # {'class': "c1", "id": "xx1"}"template_name": self.template_name, # "django/forms/widgets/text.html"# "type":"text"},}class Input(Widget):input_type = None  # Subclasses must define this.template_name = "django/forms/widgets/input.html"def __init__(self, attrs=None):if attrs is not None:attrs = attrs.copy()self.input_type = attrs.pop("type", self.input_type)super().__init__(attrs)def get_context(self, name, value, attrs):# {"widget":{"name":}   }context = super().get_context(name, value, attrs)context["widget"]["type"] = self.input_typereturn contextclass TextInput(Input):input_type = "text"template_name = "django/forms/widgets/text.html"class PasswordInput(Input):input_type = "password"template_name = "django/forms/widgets/password.html"def __init__(self, attrs=None, render_value=False):super().__init__(attrs)self.render_value = render_valuedef get_context(self, name, value, attrs):if not self.render_value:value = Nonereturn super().get_context(name, value, attrs)

from django.shortcuts import HttpResponse
from django.template.loader import get_templatefrom django import formsdef v1(request):template = get_template("v1.html")text = template.render({"text": "张开"}, request)print(text)return HttpResponse("OK")def v2(request):# 1.执行 TextInput的 __init__方法obj = forms.TextInput(attrs={'class': "c1", "id": "xx1"})data_string = obj.render(name="user", value="张开")print(data_string)  # <input type='text' name='user' value="张开" class="c1"  id="xx1" />obj2 = forms.PasswordInput(attrs={'class': "c2"}, render_value=True)data_string = obj2.render(name="user", value="张开")print(data_string)return HttpResponse("OK")

3.init和new

class Foo(object):def __init__(self,name):self.name = name # 1. __new__ 去创建空对象 {}   -> 构造方法（创建对象）
# 2. __init__在对象中进行初始化 {"name":"武沛齐"}   -> 初始化方法
obj = Foo("武沛齐")

class Foo(object):def __init__(self, name):print("init初始化", self)self.name = namedef __new__(cls, *args, **kwargs):obj = super().__new__(cls)print("new创建对象", obj)return objinstance = Foo("wupeiqi")
print("得到对象", instance)

4.元类

说两句：

• 默认情况下，类都是由type创建；

  class Info(object):city = "背景"def show(self):print("123")# Info = type("Info", (object,), {"city": "背景", "show": lambda self: print(123)})obj = Info()
  print(obj.city)
  obj.show()
  

• 想要由其他的东西创建类，就可以使用metaclass进行指定。

  class Info(object,metaclass=其他):city = "背景"def show(self):print("123")
  

  class MyType(type):passclass Info(object, metaclass=MyType):city = "背景"def show(self):print("123")
  

类是有type创建的，类又可以进行实例化，去创建对象。

class MyType(type):# def __init__(self, *args, **kwargs):#     super().__init__(*args, **kwargs)def __new__(cls, *args, **kwargs):clazz = super().__new__(cls, *args, **kwargs)clazz.base_declare = [11, 22, 33]return clazzclass Info(object, metaclass=MyType):city = "背景"def show(self):print("123")print(Info.base_declare)

5.isintance

判断某个对象是否是某个类或其子类创建的对象。

class Foo(object):passclass Info(object):passobj1 = Foo()
obj2 = Foo()print(isinstance(obj1, Foo))
print(isinstance(obj2, Info))

class Field(object):passclass CharField(Field):passclass EmailField(Field):passclass ImageField(Field):passobj1 = CharField()
obj2 = EmailField()
obj3 = ImageField()print(isinstance(obj1, Field))
print(isinstance(obj2, Field))
print(isinstance(obj3, Field))

功能：很多对象可以判断这些对象，都是我Field的子类创建的对象。

2.2 Form组件-定义类

class DeclarativeFieldsMetaclass(MediaDefiningClass):"""Collect Fields declared on the base classes."""def __new__(mcs, name, bases, attrs):# Collect fields from current class and remove them from attrs.attrs["declared_fields"] = {key: attrs.pop(key)for key, value in list(attrs.items())if isinstance(value, Field)}new_class = super().__new__(mcs, name, bases, attrs)# Walk through the MRO.declared_fields = {}for base in reversed(new_class.__mro__):# Collect fields from base class.if hasattr(base, "declared_fields"):declared_fields.update(base.declared_fields)# Field shadowing.for attr, value in base.__dict__.items():if value is None and attr in declared_fields:declared_fields.pop(attr)new_class.base_fields = declared_fieldsnew_class.declared_fields = declared_fieldsreturn new_class

from django import formsclass Form(BaseForm, metaclass=DeclarativeFieldsMetaclass):passclass LoginForm(forms.Form):username = forms.CharField(label="用户名", required=True, widget=forms.TextInput)pwd = forms.CharField(label="密码", required=True, widget=forms.PasswordInput)

LoginForm类其实是由DeclarativeFieldsMetaclass创建的【new】【init】。

2.3 Form组件-创建类的对象

from django import formsclass LoginForm(forms.Form):username = forms.CharField(label="用户名", required=True, widget=forms.TextInput)pwd = forms.CharField(label="密码", required=True, widget=forms.PasswordInput)

form = LoginForm() # __new__   __init__

class BaseForm(RenderableFormMixin):field_order = Nonedef __init__(self,data=None,files=None,auto_id="id_%s",prefix=None,initial=None,....,field_order=None,renderer=None):self.fields = copy.deepcopy(self.base_fields)self.order_fields(  self.field_order if field_order is None else field_order   )self.initial = initial or {}renderer = get_default_renderer()self.renderer = rendererdef order_fields(self, field_order):if field_order is None:returnfields = {}for key in field_order:try:fields[key] = self.fields.pop(key)except KeyError:  # ignore unknown fieldspassfields.update(self.fields)  # add remaining fields in original orderself.fields = fieldsclass Form(BaseForm, metaclass=DeclarativeFieldsMetaclass):passclass LoginForm(forms.Form):username = forms.CharField(label="用户名", required=True, widget=forms.TextInput)pwd = forms.CharField(label="密码", required=True, widget=forms.PasswordInput)form = LoginForm(initial={})

2.4 Form组件-对象.字段

class LoginForm(forms.Form):username = forms.CharField(label="用户名", required=True, widget=forms.TextInput)pwd = forms.CharField(label="密码", required=True, widget=forms.PasswordInput)

def v3(request):form = LoginForm()print(form['username'])  # form.username <input type="text" name="username" required id="id_username">return HttpResponse("OK")

class Foo(object):def __getitem__(self, item):return 999obj = Foo()print(obj)
print(obj['xxxx'])

class BoundField:"A Field plus data"def __init__(self, form, field, name):self.form = form    # Form对象self.field = field  #  forms.CharField(label="用户名", required=True, widget=forms.TextInput)self.name = name    # "username"self.html_name = form.add_prefix(name)self.html_initial_name = form.add_initial_prefix(name)self.html_initial_id = form.add_initial_prefix(self.auto_id)if self.field.label is None:self.label = pretty_name(name)else:self.label = self.field.labelself.help_text = field.help_text or ""def __str__(self):"""Render this field as an HTML widget."""return self.as_widget() # <input type="text" name="username" required id="id_username">def as_widget(self, widget=None, attrs=None, only_initial=False):# 插件对象widget = widget or self.field.widgetif self.field.localize:widget.is_localized = Trueattrs = attrs or {}attrs = self.build_widget_attrs(attrs, widget)if self.auto_id and "id" not in widget.attrs:attrs.setdefault("id", self.html_initial_id if only_initial else self.auto_id)if only_initial and self.html_initial_name in self.form.data:# Propagate the hidden initial value.value = self.form._widget_data_value(self.field.hidden_widget(),self.html_initial_name,)else:value = self.value()# 字符串= 插件forms.TextInput对象.render  《input name='?' class=".."/>return widget.render(name=self.html_initial_name if only_initial else self.html_name,value=value,attrs=attrs,renderer=self.form.renderer,)

2.5 Form组件-可迭代对象

class MyForm(object):def __iter__(self):return iter([11, 22, 33, 44])obj = MyForm()
for item in obj:print(item)