Python---The form component in Django (validation using custom methods before data is added, and source analysis)

Form Component code:

 fromapp02.models Import User fromdjango.core.exceptions Import ValidationErrorclassAjaxform (forms. Form): User=Fields . Charfield (Required=True, Min_length=3, Max_length=7,) email=Fields . Emailfield (Required=True,) #自定义方法 the Clean_ field name #必须返回值self. cleaned_data[ ' user '] #如果出错抛出raise validationerror ("Error ...")
#会在基础验证成功后, use a custom method to verify the def clean_user (self): v= self.cleaned_data[' user '] if User.objects.filter (username=v). Count (): #重复了 raise Valida Tionerror ("User name already exists") return v def clean_email (self): return self.cleaned_data[' email ']

If duplicate data is found in the database, an error is thrown.

Views Code:

def Ajax (req):ifReq.method = ="GET": obj=Ajaxform ()returnRender (req,"ajax.html",{"obj": obj}) Else: Ret={} obj=Ajaxform (req. POST)if obj.is_valid (): #在使用is_valid之后才会将数据进行验证ret['Status']="OK"            returnHttpResponse (Json.dumps (ret))Else: Print (obj.errors) ret['message']=obj.errorsreturnHttpResponse (Json.dumps (ret))

Start validating code after Is_valid and enter from here

Source view:

class baseform:       def is_valid (self):        "" "        Returns True If the form has no errors. Otherwise, False. If errors        is being ignored, returns FALSE.         "" returns True        if the form data is correct return self.errors #是属性方法 for field validation

 is  is not None #data传入表单数据不为空, so is_bound=true

Consider self.errors:

    @property    def errors (self):        "Returns a errordict forthedata provided for the form< /c5>"#返回错误信息为表单数据        if  is None:  #初始self. _errors is null                Self.full_clean () #进入该方法         return self._errors

Tracking Self.full_clean ():

def Full_clean (self):"""cleans all of self.data and populates self._errors and Self.cleaned_data. """Self._errors =errordict () #初始化错误字典ifNot Self.is_bound: # Stop further processing. returnSelf.cleaned_data={} #初始化正确数据 # If the form ispermitted to is empty, and none of the form data has # changed fromThe initial data, Shortcircuit any validation. ifself.empty_permitted and not self.has_changed (): #如果允许为空, and the data is changed from the initial state, it is returned directlyreturn#下面是开始验证的方法 Self._clean_fields () self._clean_form () Self._post_clean ( )

Start validation field: Self._clean_fields ()

def _clean_fields (self):
#循环字段, the field that is set in the form component, which is from the __new__ of Declarativefieldsmetaclass forName, fieldinchSelf.fields.items (): # value_from_datadict () gets the data fromThe data dictionaries. # Each widget type knows what to retrieve it own data, because some # widgets split data over several HTML Fiel            Ds. ifField.disabled:value=Self.get_initial_for_field (field, name)Else: Value=field.widget.value_from_datadict (Self.data, Self.files, Self.add_prefix (name))Try:                ifisinstance (field, Filefield): initial=Self.get_initial_for_field (field, name) value=Field.clean (value, initial)Else: Value=Field.clean (value) Self.cleaned_data[name]=value
　　　　　　　　　#上面尝试进行正则验证, after validation succeeds, the following logic begins
#会调用 clean_%s Method name is the field name, and this is our custom method, we can have the data after the regular validation has been satisfied
#上再次进行自定义函数的验证, such as verifying the uniqueness of database data processing ifHasattr (Self,'clean_%s'%name): Value= GetAttr (self,'clean_%s'%name) () Self.cleaned_data[name]=value #注意: The final value depends on the custom method: If the method already exists except validationerror  ase: #在自定义方法上, if the validation is wrong, we need to throw the error to get the method to capture self.add_error (name, E)

Python---The form component in Django (validation using custom methods before data is added, and source analysis)