检查值是否存在，如果存在，则将该值添加到现有值中。

huangapple
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英文:

Check if value exists, if so, add value to existing value

问题

我正在为您翻译以下内容：

对于我正在构建的一个小应用程序，我想要做以下操作：

检查是否已经存在一个具有所选账户的此“spirit”的记录。如果存在，则将“amount”值添加到现有记录中。如果不存在，则添加新记录。

我正在使用crispy forms来显示表单，并使用formset来动态添加额外的项目。
我相当确定我需要在if form.is_valid():之后进行此检查，但我不知道如何做。这样做正确吗？如果是这样，我该如何做？

请查看我的模型代码：

  1. class Spirits(models.Model):
  2.     name = models.CharField(max_length=255)
  4.     def __str__(self):
  5.         return self.name
  8. class Account(models.Model):
  9.     name = models.CharField(max_length=255)
  11.     def __str__(self):
  12.         return self.name
  14.     def get_absolute_url(self):
  15.         return reverse("forecast:account_detail", kwargs={"pk": self.pk})
  18. class VolumeItem(models.Model):
  19.     account = models.ForeignKey(Account, on_delete=models.CASCADE)
  20.     spirit = models.ForeignKey(Spirits, on_delete=models.CASCADE)
  21.     amount = models.IntegerField()
  23.     def __str__(self):
  24.         return f"{self.account}, {self.spirit} - {self.amount}"

以及我的forms.py代码：

  1. class VolumeForm(forms.ModelForm):
  2.     class Meta:
  3.         model = VolumeItem
  4.         fields = ('spirit', 'amount')
  7. ItemForecastFormSet = inlineformset_factory(
  8.     Account,
  9.     VolumeItem,
  10.     form=VolumeForm,
  11.     min_num=1,
  12.     extra=0,
  13.     can_delete=False
  14. )
  16. class FormSetHelper(FormHelper):
  17.     def __init__(self, *args, **kwargs):
  18.         super(FormSetHelper, self).__init__(*args, **kwargs)
  19.         self.layout = Layout(
  20.             Div(
  21.                 Row(
  22.                     Column('spirit', css_class='form-group col-md-6'),
  23.                     Column('amount', css_class='form-group col-md-6'),
  24.                 ),
  25.                 Row(
  26.                     Submit('submit', 'Add', css_class='my-3 btn btn-secondary')
  27.                 )
  28.             )
  29.         )

我的视图当前如下所示：

  1. def account_detail_view(request, pk):
  3.     account_detail = get_object_or_404(Account, pk=pk)
  4.     forecast_items = VolumeItem.objects.filter(account=account_detail.id)
  5.     formset = ItemForecastFormSet(request.POST or None)
  6.     helper = FormSetHelper
  8.     if request.method == 'POST':
  9.         if formset.is_valid():
  10.             formset.instance = account_detail
  11.             formset.save()
  12.             return redirect('forecast:account_detail', pk=account_detail.pk)
  14.     context = {
  15.         'account': account_detail,
  16.         'forecast_items': forecast_items,
  17.         'formset': formset,
  18.         'helper': helper
  19.     }
  21.     return render(request, 'forecast/account_detail.html', context)
英文:

For a small app I'm building I want to do the following:

Check if there already is a record with this spirit for the selected account. If so, add the amount value to the existing record. If not, add new record.

I am using crispy forms to display the form and use a formset to dynamically add extra items.
I'm pretty sure I need to do this check after the if form.is_valid(): but I do not know how. Is this correct? And if so, how do I do this?

See my Model here:

  1. class Spirits(models.Model):
  2.     name = models.CharField(max_length=255)
  4.     def __str__(self):
  5.         return self.name 
  8. class Account(models.Model):
  9.     name = models.CharField(max_length=255)
  11.     def __str__(self):
  12.        return self.name
  13.     
  14.     def get_absolute_url(self):
  15.         return reverse("forecast:account_detail", kwargs={"pk": self.pk})
  17. class VolumeItem(models.Model):
  18.     account = models.ForeignKey(Account, on_delete=models.CASCADE)
  19.     spirit = models.ForeignKey(Spirits, on_delete=models.CASCADE)
  20.     amount = models.IntegerField()
  21.     
  22.     def __str__(self):
  23.         return f"{self.account}, {self.spirit} - {self.amount}"

And my forms.py here:

  1. class VolumeForm(forms.ModelForm):
  2.     class Meta:
  3.         model = VolumeItem
  4.         fields = ('spirit','amount')
  7. ItemForecastFormSet = inlineformset_factory(
  8.     Account,
  9.     VolumeItem,
  10.     form=VolumeForm,
  11.     min_num=1,
  12.     extra=0,
  13.     can_delete=False
  14. )
  16. class FormSetHelper(FormHelper):
  17.     def __init__(self, *args, **kwargs):
  18.         super(FormSetHelper, self).__init__(*args, **kwargs)
  19.         self.layout = Layout(
  20.             Div(
  21.                 Row(
  22.                     Column('spirit', css_class='form-group col-md-6'),
  23.                     Column('amount', css_class='form-group col-md-6'),
  24.                 ),
  25.                 Row(
  26.                     Submit('submit', 'Add', css_class='my-3 btn btn-secondary')
  27.                 )
  28.             )
  29.         )

My view currently looks like this:

  1. def account_detail_view(request, pk):
  3.     account_detail = get_object_or_404(Account, pk=pk)
  4.     forecast_items = VolumeItem.objects.filter(account=account_detail.id)
  5.     formset = ItemForecastFormSet(request.POST or None)
  6.     helper = FormSetHelper
  8.     if request.method == 'POST':
  9.         if formset.is_valid():
  10.             formset.instance=account_detail
  11.             formset.save()
  12.             return redirect('forecast:account_detail', pk=account_detail.pk)
  14.     context = {
  15.         'account' : account_detail,
  16.         'forecast_items' : forecast_items,
  17.         'formset' : formset,
  18.         'helper' : helper
  19.     }
  21.     return render(request,'forecast/account_detail.html',context)

答案1

得分: 1

你可以重写表单的保存方法来获取实例并添加金额，或者创建一个新的记录。

  1. class VolumeForm(forms.ModelForm):
  2.     class Meta:
  3.         model = VolumeItem
  4.         fields = ('spirit', 'amount')
  6.     def save(self, commit=True):
  7.         try:
  8.             instance = VolumeItem.objects.get(account=self.cleaned_data['account'], spirit=self.cleaned_data['spirit'])
  9.             instance.amount += self.cleaned_data["amount"]
  10.             instance.save()
  11.         except VolumeItem.DoesNotExist:
  12.             instance = super().save()
  13.         return instance

请注意，这是一个示例代码，你需要根据你的实际需求进行适当的修改。

英文:

You can override the form save method to get the instace and add the amount or create a new record.

  1. class VolumeForm(forms.ModelForm):
  2.     class Meta:
  3.         model = VolumeItem
  4.         fields = ('spirit','amount')
  6.     def save(self, commit=True):
  7.         try:
  8.             instance = VolumeItem.objects.get(account=self.cleaned_data['account'], spirit=self.cleaned_data['spirit'])
  9.             instance.amount += self.cleaned_data["amount"]
  10.             instance.save()
  11.         except VolumeItem.DoesNotExist:
  12.             instance = super().save()
  13.         return instance

huangapple
  • 本文由 发表于 2023年7月27日 14:55:00
  • 转载请务必保留本文链接：https://go.coder-hub.com/76777166.html
  • django
  • django-forms
  • django-models
  • django-views
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