[django] ORM Admin

5. 扩展

   1.触发Model中的验证和错误提示有两种方式：
       a. Django Admin中的错误信息会优先根据Admiin内部的ModelForm错误信息提示，如果都成功，才来检查Model的字段并显示指定错误信息
       b. 调用Model对象的 clean_fields 方法，如：
           # models.py
           class UserInfo(models.Model):
               nid = models.AutoField(primary_key=True)
               username = models.CharField(max_length=32)
   
               email = models.EmailField(error_messages={'invalid': '格式错了.'})
   
           # views.py
           def index(request):
               obj = models.UserInfo(username='11234', email='uu')
               try:
                   print(obj.clean_fields())
               except Exception as e:
                   print(e)
               return HttpResponse('ok')
   
          # Model的clean方法是一个钩子，可用于定制操作，如：上述的异常处理。
   
   2.Admin中修改错误提示
       # admin.py
       from django.contrib import admin
       from model_club import models
       from django import forms
   
   
       class UserInfoForm(forms.ModelForm):
           username = forms.CharField(error_messages={'required': '用户名不能为空.'})
           email = forms.EmailField(error_messages={'invalid': '邮箱格式错误.'})
           age = forms.IntegerField(initial=1, error_messages={'required': '请输入数值.', 'invalid': '年龄必须为数值.'})
   
           class Meta:
               model = models.UserInfo
               # fields = ('username',)
               fields = "__all__"
   
   
       class UserInfoAdmin(admin.ModelAdmin):
           form = UserInfoForm
   
       admin.site.register(models.UserInfo, UserInfoAdmin)