python,day22-Django之Form组件，信号

Django的Form主要具有一下几大功

能：生成HTML标签验证用户数据（显示错误信息）HTML Form提交保留上次提交数据初始化页面显示内容1、创建Form类

from django.forms import Formfrom django.forms import widgetsfrom django.forms import fieldsclass MyForm(Form):user = fields.CharField(widget=widgets.TextInput(attrs={'id': 'i1', 'class': 'c1'}))gender = fields.ChoiceField(choices=((1, '男'), (2, '女'),),initial=2,widget=widgets.RadioSelect)city = fields.CharField(initial=2,widget=widgets.Select(choices=((1,'上海'),(2,'北京'),)))pwd = fields.CharField(widget=widgets.PasswordInput(attrs={'class': 'c1'}, render_value=True))

2、View函数处理

from django.shortcuts import render, redirectfrom .forms import MyFormdef index(request):if request.method == "GET":obj = MyForm()return render(request, 'index.html', {'form': obj})elif request.method == "POST":obj = MyForm(request.POST, request.FILES)if obj.is_valid():values = obj.clean()print(values)else:errors = obj.errorsprint(errors)return render(request, 'index.html', {'form': obj})else:return redirect('http://www.google.com')

3、生成HTML

<form action="/" method="POST" enctype="multipart/form-data"><p>{{ form.user }} {{ form.user.errors }}</p><p>{{ form.gender }} {{ form.gender.errors }}</p><p>{{ form.city }} {{ form.city.errors }}</p><p>{{ form.pwd }} {{ form.pwd.errors }}</p><input type="submit"/></form>

其它标签

<form method="POST" enctype="multipart/form-data">{% csrf_token %}{{ form.xxoo.label }}{{ form.xxoo.id_for_label }}{{ form.xxoo.label_tag }}{{ form.xxoo.errors }}<p>{{ form.user }} {{ form.user.errors }}</p><input type="submit" /></form>

Form类

创建Form类时，主要涉及到 【字段】 和 【插件】，字段用于对用户请求数据的验证，插件用于自动生成HTML;1、Django内置字段如下：注：UUID是根据MAC以及当前时间等创建的不重复的随机字符串

>>> import uuid# make a UUID based on the host ID and current time>>> uuid.uuid1()    # doctest: +SKIPUUID('a8098c1a-f86e-11da-bd1a-00112444be1e')# make a UUID using an MD5 hash of a namespace UUID and a name>>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')# make a random UUID>>> uuid.uuid4()    # doctest: +SKIPUUID('16fd2706-8baf-433b-82eb-8c7fada847da')# make a UUID using a SHA-1 hash of a namespace UUID and a name>>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')# make a UUID from a string of hex digits (braces and hyphens ignored)>>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')# convert a UUID to a string of hex digits in standard form>>> str(x)'00010203-0405-0607-0809-0a0b0c0d0e0f'# get the raw 16 bytes of the UUID>>> x.bytesb'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'# make a UUID from a 16-byte string>>> uuid.UUID(bytes=x.bytes)UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')

2、Django内置插件：

TextInput(Input)NumberInput(TextInput)EmailInput(TextInput)URLInput(TextInput)PasswordInput(TextInput)HiddenInput(TextInput)Textarea(Widget)DateInput(DateTimeBaseInput)DateTimeInput(DateTimeBaseInput)TimeInput(DateTimeBaseInput)CheckboxInputSelectNullBooleanSelectSelectMultipleRadioSelectCheckboxSelectMultipleFileInputClearableFileInputMultipleHiddenInputSplitDateTimeWidgetSplitHiddenDateTimeWidgetSelectDateWidget

常用选择插件

<form method="POST" enctype="multipart/form-data">{% csrf_token %}<p>{{ form.user }} {{ form.user.errors }}</p><p>{{ form.city }} {{ form.city.errors }}</p><input type="submit"/></form>

信号

Django中提供了“信号调度”，用于在框架执行操作时解耦。通俗来讲，就是一些动作发生的时候，信号允许特定的发送者去提醒一些接受者。1、Django内置信号

Model signalspre_init                    # django的modal执行其构造方法前，自动触发post_init                   # django的modal执行其构造方法后，自动触发pre_save                    # django的modal对象保存前，自动触发post_save                   # django的modal对象保存后，自动触发pre_delete                  # django的modal对象删除前，自动触发post_delete                 # django的modal对象删除后，自动触发m2m_changed                 # django的modal中使用m2m字段操作第三张表（add,remove,clear）前后，自动触发class_prepared              # 程序启动时，检测已注册的app中modal类，对于每一个类，自动触发Management signalspre_migrate                 # 执行migrate命令前，自动触发post_migrate                # 执行migrate命令后，自动触发Request/response signalsrequest_started             # 请求到来前，自动触发request_finished            # 请求结束后，自动触发got_request_exception       # 请求异常后，自动触发Test signalssetting_changed             # 使用test测试修改配置文件时，自动触发template_rendered           # 使用test测试渲染模板时，自动触发Database Wrappersconnection_created          # 创建数据库连接时，自动触发

对于Django内置的信号，仅需注册指定信号，当程序执行相应操作时，自动触发注册函数：

from django.core.signals import request_finishedfrom django.core.signals import request_startedfrom django.core.signals import got_request_exceptionfrom django.db.models.signals import class_preparedfrom django.db.models.signals import pre_init, post_initfrom django.db.models.signals import pre_save, post_savefrom django.db.models.signals import pre_delete, post_deletefrom django.db.models.signals import m2m_changedfrom django.db.models.signals import pre_migrate, post_migratefrom django.test.signals import setting_changedfrom django.test.signals import template_renderedfrom django.db.backends.signals import connection_createddef callback(sender, **kwargs):print("xxoo_callback")print(sender,kwargs)xxoo.connect(callback)# xxoo指上述导入的内容

from django.core.signals import request_finishedfrom django.dispatch import receiver@receiver(request_finished)def my_callback(sender, **kwargs):print("Request finished!")

2、自定义信号a. 定义信号

import django.dispatchpizza_done = django.dispatch.Signal(providing_args=["toppings", "size"])

b. 注册信号

def callback(sender, **kwargs):print("callback")print(sender,kwargs)pizza_done.connect(callback)

c. 触发信号

from 路径 import pizza_donepizza_done.send(sender='seven',toppings=123, size=456)

由于内置信号的触发者已经集成到Django中，所以其会自动调用，而对于自定义信号则需要开发者在任意位置触发。