[django]Manipulator解惑

代码下载：/Files/maplye/django/Study914.rar

Manipulator英语翻译成“操纵器”，你可以用它来创建，修改，验证你的一个实体对象，并结合FormWrapper可以自动生成页面上Html代码（注：FormWrapper是用来生成html代码，Manipulator使为FormWrapper提供数据和数据模型等）。

 

django系统已经带有两种Manipulator，一是AddManipulator，二是ChangeManipulator，我以前一直以为这是model的两个方法，还有ChangeManipulator我以为是为我的model更换一个Manipulator,其实他是两个不同的类。这两个类能够自动根据model来生成validation和save。AddManipulator和ChangeManipulator都是继承自Manipulator，不同的是ChangeManipulator带有一objectid的构造参数，并获取一object赋值给他的original_object属性，并在save方法使用修改对象，然后保存该对象。

关于这两种Manipulator的使用，可以参考django document:

http://www.djangoproject.com/documentation/forms/

 

除了django提供的两种Manipulator,我们还可以自定义Manipulator,这样我们定义自己的fields,validation,save等等。

如：

from  django  import  forms

urgency_choices  =  (
    ( 1 ,  " Extremely urgent " ),
    ( 2 ,  " Urgent " ),
    ( 3 ,  " Normal " ),
    ( 4 ,  " Unimportant " ),
)

class  ContactManipulator(forms.Manipulator):
     def   __init__ (self):
        self.fields  =  (
            forms.EmailField(field_name = " from " , is_required = True),
            forms.TextField(field_name = " subject " , length = 30 , maxlength = 200 , is_required = True),
            forms.SelectField(field_name = " urgency " , choices = urgency_choices),
            forms.LargeTextField(field_name = " contents " , is_required = True),
        )
     def  save(self):         # .

而且我们还可以定义带有初始化参数的custom Manipulator
如：

class  ContactManipulator(forms.Manipulator):
     def   __init__ (self,object_id = None):
        self.object_id  =  object_id
        self.fields  =  (
            forms.EmailField(field_name = " fromEmail " , is_required = True),
            forms.TextField(field_name = " subject " , length = 30 , maxlength = 200 , is_required = True),
            forms.SelectField(field_name = " urgency " , choices = urgency_choices),
            forms.LargeTextField(field_name = " contents " , is_required = True),
        )

     def  save(self, new_data):
        fromemail  =  new_data[ " fromEmail " ]
        subject  =  new_data[ " subject " ]
        urgency  =  new_data[ " urgency " ]
        contents  =  new_data[ " contents " ]
         if  self.object_id:
            obj  =  Contact.objects.get(pk = int(self.object_id))
            obj.fromEmail  =  fromemail
            obj.subject  =  subject
            obj.urgency  =  urgency;
            obj.contents  =  contents;
         else :
            obj  =  Contact(fromEmail = fromemail, subject = subject, urgency = urgency,contents = contents)
        obj.save()

你看上面ContactManipulator的Manipulator就具有AddManipulator和ChangeManipulator两个的功能，
那这个ContactManipulator应该怎么用呢

# 创建   
def  contact_form(request):
    manipulator  =  ContactManipulator()
     if  request.POST:
        new_data  =  request.POST.copy()
        errors  =  manipulator.get_validation_errors(new_data)
         if   not  errors:
            manipulator.do_html2python(new_data)

            manipulator.save(new_data)
             return  HttpResponseRedirect( " /formapp/contact/ " )
     else :
        errors  =  new_data  =  {}
        
    form  =  forms.FormWrapper(manipulator, new_data, errors)
     return  render_to_response( ' places/contact_form.html ' , { ' form ' : form})

# 修改
def  editcontact(request,contactid):
    manipulator  =  ContactManipulator(contactid)
    
     if  request.POST:
        new_data  =  request.POST.copy()
        errors  =  manipulator.get_validation_errors(new_data)
         if   not  errors:
            manipulator.do_html2python(new_data)
            manipulator.save(new_data)

             #  Do a post-after-redirect so that reload works, etc.
             return  HttpResponseRedirect( " /formapp/contact/1 " )
     else :
        errors  =  {}        
        contact  =  Contact.objects.get(id  =  contactid)
        new_data  =  contact. __dict__
    
    form  =  forms.FormWrapper(manipulator, new_data,errors )
     return  render_to_response( ' places/contact_form.html ' , { ' form ' : form})        

以上是我在学习Manipulator时一些个人理解，暂时记录如此，以后我会更深入的了解他们，同时非常感谢limodou的解惑，他真是个热心人，向他学习！