Flask 第三方组件之 WTForms
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Flask 第三方组件之 WTForms
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簡介
WTForms是一個支持多個web框架的form組件，主要用于對用戶請求數據進行驗證。
安裝： pip3 install wtforms
用戶登錄注冊示例
1. 用戶登錄
當用戶登錄時候，需要對用戶提交的用戶名和密碼進行多種格式校驗。如：
- 用戶不能為空；用戶長度必須大于6；
- 密碼不能為空；密碼長度必須大于12；密碼必須包含 字母、數字、特殊字符等（自定義正則）；
2. 用戶注冊
注冊頁面需要讓用戶輸入：用戶名、密碼、密碼重復、性別、愛好等。
############################## app.py ############################# from flask import Flask, render_template, request, redirect from wtforms import Form from wtforms.fields import core from wtforms.fields import html5 from wtforms.fields import simple from wtforms import validators from wtforms import widgetsapp = Flask(__name__, template_folder='templates') app.debug = Trueclass RegisterForm(Form):name = simple.StringField(label='用戶名',validators=[validators.DataRequired()],widget=widgets.TextInput(),render_kw={'class': 'form-control'},default='alex')pwd = simple.PasswordField(label='密碼',validators=[validators.DataRequired(message='密碼不能為空.')],widget=widgets.PasswordInput(),render_kw={'class': 'form-control'})pwd_confirm = simple.PasswordField(label='重復密碼',validators=[validators.DataRequired(message='重復密碼不能為空.'),validators.EqualTo('pwd', message="兩次密碼輸入不一致")],widget=widgets.PasswordInput(),render_kw={'class': 'form-control'})email = html5.EmailField(label='郵箱',validators=[validators.DataRequired(message='郵箱不能為空.'),validators.Email(message='郵箱格式錯誤')],widget=widgets.TextInput(input_type='email'),render_kw={'class': 'form-control'})gender = core.RadioField(label='性別',choices=((1, '男'),(2, '女'),),coerce=int # 會自動轉化為int)city = core.SelectField(label='城市',choices=(('bj', '北京'),('sh', '上海'),))hobby = core.SelectMultipleField(label='愛好',choices=((1, '籃球'),(2, '足球'),),coerce=int)favor = core.SelectMultipleField(label='喜好',choices=((1, '籃球'),(2, '足球'),),widget=widgets.ListWidget(prefix_label=False),option_widget=widgets.CheckboxInput(),coerce=int,default=[1, 2])def __init__(self, *args, **kwargs):super(RegisterForm, self).__init__(*args, **kwargs)self.favor.choices = ((1, '籃球'), (2, '足球'), (3, '羽毛球'))def validate_pwd_confirm(self, field): # 鉤子函數，filed 代表要檢驗的字段，self 代表所有的數據"""自定義pwd_confirm字段規則，例：與pwd字段是否一致:param field: :return: """# 最開始初始化時，self.data中已經有所有的值if field.data != self.data['pwd']:# raise validators.ValidationError("密碼不一致") # 繼續后續驗證，驗證的是本字段raise validators.StopValidation("密碼不一致") # 不再繼續后續驗證，驗證的是本字段@app.route('/register', methods=['GET', 'POST']) def register():if request.method == 'GET':form = RegisterForm(data={'gender': 1}) # data 為form 傳值return render_template('register.html', form=form)else:form = RegisterForm(formdata=request.form)if form.validate():print('用戶提交數據通過格式驗證，提交的值為：', form.data)else:print(form.errors)return render_template('register.html', form=form)if __name__ == '__main__':app.run() ############################## login.html ############################# <!DOCTYPE html> <html lang="en"> <head><meta charset="UTF-8"><title>Title</title> </head> <body> <h1>用戶注冊</h1> <form method="post" novalidate style="padding:0 50px">{% for item in form %}<p>{{item.label}}: {{item}} {{item.errors[0] }}</p>{% endfor %}<input type="submit" value="提交"> </form> </body> </html>3. meta
使用WTFrom 提供的 csrf_token，一般不怎么用
#!/usr/bin/env python # -*- coding:utf-8 -*- from flask import Flask, render_template, request, redirect, session from wtforms import Form from wtforms.csrf.core import CSRF from wtforms.fields import core from wtforms.fields import html5 from wtforms.fields import simple from wtforms import validators from wtforms import widgets from hashlib import md5app = Flask(__name__, template_folder='templates') app.debug = Trueclass MyCSRF(CSRF): # 繼承CSRF，實現自己的規則"""Generate a CSRF token based on the user's IP. I am probably not verysecure, so don't use me."""def setup_form(self, form):self.csrf_context = form.meta.csrf_context()self.csrf_secret = form.meta.csrf_secretreturn super(MyCSRF, self).setup_form(form)def generate_csrf_token(self, csrf_token):gid = self.csrf_secret + self.csrf_contexttoken = md5(gid.encode('utf-8')).hexdigest()return tokendef validate_csrf_token(self, form, field):print(field.data, field.current_token)if field.data != field.current_token:raise ValueError('Invalid CSRF')class TestForm(Form):name = html5.EmailField(label='用戶名')pwd = simple.StringField(label='密碼')class Meta:# -- CSRF# 是否自動生成CSRF標簽csrf = True# 生成CSRF標簽namecsrf_field_name = 'csrf_token'# 自動生成標簽的值，加密用的csrf_secretcsrf_secret = 'xxxxxx'# 自動生成標簽的值，加密用的csrf_contextcsrf_context = lambda x: request.url# 生成和比較csrf標簽csrf_class = MyCSRF# -- i18n# 是否支持本地化# locales = Falselocales = ('zh', 'en')# 是否對本地化進行緩存cache_translations = True# 保存本地化緩存信息的字段translations_cache = {}@app.route('/index/', methods=['GET', 'POST']) def index():if request.method == 'GET':form = TestForm()else:form = TestForm(formdata=request.form)if form.validate():print(form)return render_template('index.html', form=form)if __name__ == '__main__':app.run()其他：
1. metaclass
第一階段
class MyType(type):def __init__(self, *args, **kwargs):print('MyType創建類',self)super(MyType, self).__init__(*args, **kwargs)def __call__(self, *args, **kwargs):obj = super(MyType, self).__call__(*args, **kwargs)print('類創建對象', self, obj)return objclass Foo(object,metaclass=MyType):user = 'flepeng'age = 18obj = Foo()第二階段
class MyType(type):def __init__(self, *args, **kwargs):super(MyType, self).__init__(*args, **kwargs)def __call__(cls, *args, **kwargs):v = dir(cls)obj = super(MyType, cls).__call__(*args, **kwargs)return objclass Foo(MyType('MyType', (object,), {})):user = 'wupeiqi'age = 18obj = Foo()第三階段
class MyType(type):def __init__(self, *args, **kwargs):super(MyType, self).__init__(*args, **kwargs)def __call__(cls, *args, **kwargs):v = dir(cls)obj = super(MyType, cls).__call__(*args, **kwargs)return objdef with_metaclass(arg,base):return MyType('MyType', (base,), {})class Foo(with_metaclass(MyType,object)):user = 'wupeiqi'age = 18obj = Foo()2. 實例化流程分析
# 源碼流程1. 執行type的 __call__ 方法，讀取字段到靜態字段 cls._unbound_fields 中； meta類讀取到cls._wtforms_meta中2. 執行構造方法a. 循環cls._unbound_fields中的字段，并執行字段的bind方法，然后將返回值添加到 self._fields[name] 中。即：_fields = {name: wtforms.fields.core.StringField(),}PS：由于字段中的__new__方法，實例化時：name = simple.StringField(label='用戶名')，創建的是UnboundField(cls, *args, **kwargs)，當執行完bind之后，才變成執行 wtforms.fields.core.StringField()b. 循環_fields，為對象設置屬性for name, field in iteritems(self._fields):# Set all the fields to attributes so that they obscure the class# attributes with the same names.setattr(self, name, field)c. 執行process，為字段設置默認值：self.process(formdata, obj, data=data, **kwargs)優先級：obj,data,formdata;再循環執行每個字段的process方法，為每個字段設置值：for name, field, in iteritems(self._fields):if obj is not None and hasattr(obj, name):field.process(formdata, getattr(obj, name))elif name in kwargs:field.process(formdata, kwargs[name])else:field.process(formdata)執行每個字段的process方法，為字段的data和字段的raw_data賦值def process(self, formdata, data=unset_value):self.process_errors = []if data is unset_value:try:data = self.default()except TypeError:data = self.defaultself.object_data = datatry:self.process_data(data)except ValueError as e:self.process_errors.append(e.args[0])if formdata:try:if self.name in formdata:self.raw_data = formdata.getlist(self.name)else:self.raw_data = []self.process_formdata(self.raw_data)except ValueError as e:self.process_errors.append(e.args[0])try:for filter in self.filters:self.data = filter(self.data)except ValueError as e:self.process_errors.append(e.args[0])d. 頁面上執行print(form.name) 時，打印標簽因為執行了：字段的 __str__ 方法字符的 __call__ 方法self.meta.render_field(self, kwargs)def render_field(self, field, render_kw):other_kw = getattr(field, 'render_kw', None)if other_kw is not None:render_kw = dict(other_kw, **render_kw)return field.widget(field, **render_kw)執行字段的插件對象的 __call__ 方法，返回標簽字符串3. 驗證流程分析
a. 執行form的validate方法，獲取鉤子方法def validate(self):extra = {}for name in self._fields:inline = getattr(self.__class__, 'validate_%s' % name, None)if inline is not None:extra[name] = [inline]return super(Form, self).validate(extra)b. 循環每一個字段，執行字段的 validate 方法進行校驗(參數傳遞了鉤子函數)def validate(self, extra_validators=None):self._errors = Nonesuccess = Truefor name, field in iteritems(self._fields):if extra_validators is not None and name in extra_validators:extra = extra_validators[name]else:extra = tuple()if not field.validate(self, extra):success = Falsereturn successc. 每個字段進行驗證時候字段的pre_validate 【預留的擴展】字段的_run_validation_chain，對正則和字段的鉤子函數進行校驗字段的post_validate【預留的擴展】 ################################## class FormMeta ############################### class FormMeta(type):# 創建類時，調用的方法def __init__(cls, name, bases, attrs):type.__init__(cls, name, bases, attrs)cls._unbound_fields = Nonecls._wtforms_meta = None# 實例化類時調用的方法def __call__(cls, *args, **kwargs):if cls._unbound_fields is None:fields = []for name in dir(cls):if not name.startswith('_'):unbound_field = getattr(cls, name)if hasattr(unbound_field, '_formfield'): # 只要是繼承自File，_formfield = Truefields.append((name, unbound_field)) # 將字段添加至fields?fields.sort(key=lambda x: (x[1].creation_counter, x[0]))cls._unbound_fields = fields # _unbound_fields?=[字段對應的示例,]if cls._wtforms_meta is None:bases = []for mro_class in cls.__mro__:if 'Meta' in mro_class.__dict__:bases.append(mro_class.Meta) # 將所有的Meta添加至bases中cls._wtforms_meta = type('Meta', tuple(bases), {}) # 創建一個新的Meta，并繼承自找到的Meta列表return type.__call__(cls, *args, **kwargs) # 執行type的call方法，前面的都是派生的 ################################## class Form ############################### # class Form(BaseForm , classmate=FormMeta) class Form(with_metaclass(FormMeta, BaseForm)):Meta = DefaultMetadef __init__(self, formdata=None, obj=None, prefix='', data=None, meta=None, **kwargs):meta_obj = self._wtforms_meta()if meta is not None and isinstance(meta, dict):meta_obj.update_values(meta)super(Form, self).__init__(self._unbound_fields, meta=meta_obj, prefix=prefix)for name, field in iteritems(self._fields):setattr(self, name, field)self.process(formdata, obj, data=data, **kwargs)def __setitem__(self, name, value):raise TypeError('Fields may not be added to Form instances, only classes.')def __delitem__(self, name):del self._fields[name]setattr(self, name, None)def __delattr__(self, name):if name in self._fields:self.__delitem__(name)else:unbound_field = getattr(self.__class__, name, None)if unbound_field is not None and hasattr(unbound_field, '_formfield'):setattr(self, name, None)else:super(Form, self).__delattr__(name)def validate(self):extra = {}for name in self._fields:inline = getattr(self.__class__, 'validate_%s' % name, None)if inline is not None:extra[name] = [inline]return super(Form, self).validate(extra) ################################## class BaseForm ############################### class BaseForm(object):def __init__(self, fields, prefix='', meta=DefaultMeta()):if prefix and prefix[-1] not in '-_;:/.':prefix += '-'self.meta = metaself._prefix = prefixself._errors = Noneself._fields = OrderedDict()if hasattr(fields, 'items'):fields = fields.items()translations = self._get_translations()extra_fields = []if meta.csrf:self._csrf = meta.build_csrf(self)extra_fields.extend(self._csrf.setup_form(self))for name, unbound_field in itertools.chain(fields, extra_fields):options = dict(name=name, prefix=prefix, translations=translations)field = meta.bind_field(self, unbound_field, options)self._fields[name] = field?
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