調用save（）後Django模型沒有被保存？

Question

我重寫了一個ModelForm的保存方法。我解析一個Excel文件，如果有一些值，我更新窗體的實例相關對象中的數量。它是第一次，當實例沒有相關的對象。但是第二次，當我更新這些值時，沒有任何反應。我不確定它是否與commit參數有關。

編輯 - 相關代碼：

def save(self, commit=True): 
    """ 
    Overrides the save method in order to add the product inventory items listed in 
    the uploaded Excel file, if one was uploaded. 
    """ 
    inventory = super(AddOrChangeProductsInventoryForm, self).save(commit) 

    self._update_inventory_items_quantities() 

    if not commit: 
     inventory.save() 
     self.save_m2m() 

    return inventory 

def _update_inventory_items_quantities(self): 
    inventory = self.instance 

    if len(self.excel_data_dict) == 0: 
     return inventory 

    non_existing_products = [] 

    for i, product_sku in enumerate(self.excel_data_dict['SKU']): 
     quantity = self.excel_data_dict['Cantidad'][i] 
     new_item = inventory.productinventoryitem_set.filter(product__sku=product_sku).first() 

     if new_item is None: 
      product = Product.objects.filter(sku=product_sku).first() 

      if product is None: 
       # TODO: Raise warning in view 
       non_existing_products.append(product_sku) 
       continue 

      new_item = ProductInventoryItem() 
      new_item.product = product 
      new_item.inventory = inventory 

     new_item.quantity += quantity 
     # TODO: Check why after first update it's not being updated 

Answer 1

如果模型有任何許多一對多的關係，那麼你需要確保在組合使用self.save_m2m()與保存方法。下面是一個簡單的例子：

# save method of your forms.ModelForm class. 
def save(self): 
    obj = super(MyModelForm, self).save(commit=False) 
    obj.save() 
    self.save_m2m() 
    return obj 

Answer 2

當commit爲False時，您正在保存表單。 替換（第10行）：

if not commit: 

與：

if commit: 

UPDATE：

new_item是inventory.productinventoryitem_set.filter(product__sku=product_sku).first()

或

ProductInventoryItem() 

新副本

這是本地變量，它不更新inventory。執行該功能後，所有這些更改都將被破壞。您需要將更改存儲在inventory中。

for obj in self.instance.productinventoryitem_set.all(): 
    obj.quantity += 2 
    obj.save() 

然後你保存更改前銷燬：

當你在重寫_save_m2m。

你可以做這樣的事情：

def save(self, commit=True): 

    inventory = super(AddOrChangeProductsInventoryForm, self).save(commit) 

    self._update_inventory_items_quantities(inventory, commit) 

    return inventory 

def _update_inventory_items_quantities(self, inventory, commit): 

    if len(self.excel_data_dict) == 0: 
     return inventory 

    non_existing_products = [] 

    for i, product_sku in enumerate(self.excel_data_dict['SKU']): 
     quantity = self.excel_data_dict['Cantidad'][i] 
     new_item = inventory.productinventoryitem_set.filter(product__sku=product_sku).first() 

     if new_item is None: 
      product = Product.objects.filter(sku=product_sku).first() 

      if product is None: 
       # TODO: Raise warning in view 
       non_existing_products.append(product_sku) 
       continue 

      new_item = ProductInventoryItem() 
      new_item.product = product 
      new_item.inventory = inventory 

     new_item.quantity += quantity 
     if commit: 
      new_item.save()