Django管理站点修改保存

Question

在管理站点中，我有一个自定义窗体。但是，我想重写save方法，以便如果输入某个关键字，则不会将其保存到数据库中。这可能吗？

class MyCustomForm (forms.ModelForm): 

    def save(self, commit=True): 
     input_name = self.cleaned_data.get('input_name', None) 
     if input_name == "MyKeyword": 
      //Do not save 
     else: 
      return super(MyCustomForm, self).save(commit=commit) 

但这返回错误：

AttributeError 'NoneType' object has no attribute 'save' 

编辑 在此之后：Overriding the save method in Django ModelForm

我想：

def save(self, force_insert=False, force_update=False, commit=True): 
    m = super(MyCustomCategoryForm, self).save(commit=False) 
    input_name = self.cleaned_data.get('input_name', None) 
    if input_name != "MyKeyword": 
     m.save() 
    return m  

但是，管理工具仍然会创建一个新的输入如果输入_name是“我的关键字”

Answer 1

save()方法应该返回对象，无论是否保存。它更应是这样的：

def save(self, commit=True): 
    input_name = self.cleaned_data.get('input_name') 
    if input_name == "MyKeyword": 
     commit = False 
    return super().save(commit=commit) 

然而，正如你可以看到here和here，形式已经被称为与commit=False和对象是由您ModelAdmin的save_model()方法后保存。这就是你得到AttributeError 'NoneType' object has no attribute 'save'的原因。如果你检查异常的回溯，我很确定这个错误来自this line。

因此，你应该，另外，覆盖您ModelAdmin的save_model()方法：

def save_model(self, request, obj, form, change): 
    if form.cleaned_data.get('input_name') == 'MyKeyword': 
     return # Don't save in this case 
    super().save_model(request, obj, form, change) 

# And you'll also have to override the `ModelAdmin`'s `save_related()` method 
# in the same flavor: 

def save_related(self, request, form, formsets, change): 
    if form.cleaned_data.get('input_name') == 'MyKeyword': 
     return # Don't save in this case 
    super().save_related(request, form, formsets, change) 

---

鉴于此回答您的评论

It is working now but I just have one related question. The admin site will still display a green banner at the top saying "The model was added successfully". Can I override some method so that it is red and says "The model already exists"?

它看起来就是你想要的要做的不是重写保存方法，而是controlling form validation。这是完全不同的。您只需重写表单的干净方法。

from django import forms 

def clean(self): 
    """ 
    super().clean() 
    if self.cleaned_data.get('input_name') == 'MyKeyword': 
     raise forms.ValidationError("The model already exists") 

，或者甚至更好，因为它看起来像你想clean a single field：

from django import form 

def clean_input_name(self): 
    data = self.cleaned_data['input_name'] 
    if data == 'MyKeyWord': 
     raise forms.ValidationError("The model already exists") 

然而，我猜input_name也是模型的一个领域，你不想提这个仅在一个表单上出现错误，但是在整个项目中出错在这种情况下，你在找什么是Model validators：

from django.core.exceptions import ValidationError 

def validate_input_name(value): 
    if value == 'MyKeyword': 
     raise ValidationError("The model already exists")