一、wtforms源碼流程

1、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，並執行字段的bind方法，然後將返回值添加到 self._fields[name] 中。
            即：
                _fields = {
                    name: wtforms.fields.core.StringField(),
                }
                
            PS：由於字段中的__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之後，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.default
        
                self.object_data = data
        
                try:
                    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

2、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 = None
                success = True
                for 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 = False
                return success
        c. 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】

二、自定義From組件

#!usr/bin/env python
# -*- coding:utf-8 -*-
from flask import Flask,render_template,request,Markup
app = Flask(__name__,template_folder="templates")
app.debug = True
# ==============通過這幾個類就可以顯示了-==============
#插件
class Widget(object):
    pass

class InputText(Widget):
    def __call__(self, *args, **kwargs):

        return "<input type=‘text‘ name=‘name‘>"

class TextArea(Widget):
    def __call__(self, *args, **kwargs):
        return Markup("<textarea name=‘email‘></textarea>")

#Form
class BaseForm(object):
    def __init__(self):
        #獲取當前所有的字段
        _fields = {}
        for name, field in self.__class__.__dict__.items():
            if isinstance(field, Field):  # 篩選出字段是name和emailDe
                _fields[name] = field
        self._fields = _fields
        self.data = {}
        # print(_fields)  # {‘name‘: 111, ‘email‘: 222}

    def validate(self,request_data):
        #先找到所有的字段，在執行每一個字段的validate方法
        flag = True
        for name, field in self._fields.items():
            input_val = request_data.get(name,"") #用戶輸入的值
            result= field.validate(input_val)  #每一個字段自己校驗
            print("???????????",input_val,result)
            if not result:
                flag = False
            else:
                self.data[name] = input_val
        return flag
#字段
class Field(object):
    ‘‘‘所有類的基類‘‘‘
    def __str__(self):          #python中的靜態字段通過類能找到，通過對象也能找到
        return Markup(self.widget())  #self就是StringField，self

class StringField(Field):  #每個字段打印的時候都要去執行__str__，所以選擇放在基類裏面，自己沒有就調用父類的
    widget = InputText()
    def validate(self,val):
        if val:
            return True

class EmaliField(Field):
    widget = TextArea()
    reg = ".*@.*"

    def validate(self,val):
        import re
        print(re.match(self.reg,val),"************")
        if re.match(self.reg,val):
            return True


# ===============使用===============
class LoginForm(BaseForm):
    name = StringField()
    email = EmaliField()

@app.route(‘/index‘, methods=["GET","POST"])
def index():
    form = LoginForm()
    ret = form.validate(request.form)
    print("驗證成功",ret)
    print("驗證成功的值",form.data)
    # print(form.name)
    # print(form.email)
    return render_template("index.html",form=form)

if __name__ == ‘__main__‘:
    app.run()

Flask系列（十）自定義Form組件