Django管理站點修改保存

Question

在管理站點中，我有一個自定義窗體。但是，我想重寫save方法，以便如果輸入某個關鍵字，則不會將其保存到數據庫中。這可能嗎？

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) 

但這返回錯誤：

AttributeError 'NoneType' object has no attribute 'save' 

編輯 在此之後：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，管理工具仍然會創建一個新的輸入如果輸入_name是「我的關鍵字」

Answer 1

save()方法應該返回對象，無論是否保存。它更應是這樣的：

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，形式已經被稱爲與commit=False和對象是由您ModelAdmin的save_model()方法後保存。這就是你得到AttributeError 'NoneType' object has no attribute 'save'的原因。如果你檢查異常的回溯，我很確定這個錯誤來自this line。

因此，你應該，另外，覆蓋您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) 

---

鑑於此回答您的評論

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"?

它看起來就是你想要的要做的不是重寫保存方法，而是controlling form validation。這是完全不同的。您只需重寫表單的乾淨方法。

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，因爲它看起來像你想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也是模型的一個領域，你不想提這個僅在一個表單上出現錯誤，但是在整個項目中出錯在這種情況下，你在找什麼是Model validators：

from django.core.exceptions import ValidationError 

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