如何在 Django 中實現 ModelChoiceField

Question

我正在嘗試從數據庫模型字段創建輸入選擇，並且我嘗試使用 ModelChoiceField，但我不斷收到錯誤，我不知道如何解決。 我需要幫助。

這是模型

class WeeklySavingsDeposit(models.Model):

    WEEKLY_SAVE_DEPOSIT_STATUS_PENDING = 'Pending'
    WEEKLY_SAVE_DEPOSIT_STATUS_APPROVED = 'Approved'
    WEEKLY_SAVE_DEPOSIT_STATUS_DENIED = 'Denied'

    WEEKLY_SAVE_DEPOSIT_STATUS_CHOICES = ((WEEKLY_SAVE_DEPOSIT_STATUS_PENDING, 'Pending'), (WEEKLY_SAVE_DEPOSIT_STATUS_APPROVED, 'Approved'), (WEEKLY_SAVE_DEPOSIT_STATUS_DENIED, 'Denied'))

    user = models.ForeignKey(User, on_delete=models.CASCADE)
    date = models.DateTimeField(default=timezone.now)
    savings_title = models.CharField(max_length=100, null = True, blank=True)
    amount = models.FloatField()
    dep_proof = models.ImageField(upload_to='deposit_proofs')
    status = models.CharField(max_length = 40, choices = WEEKLY_SAVE_DEPOSIT_STATUS_CHOICES, default='Pending')
    dep_tag = models.IntegerField(default=0)


    def __str__(self):
        return f'{self.user.username} WeeklySaveDeposit'

class WeeklySaving(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    created = models.DateTimeField(default=timezone.now)
    title = models.CharField(max_length = 100, default = 'Weekly Savings Title')
    duration = models.CharField(max_length=40, choices=WEEKLY_SAVE_DURATION_CHOICES, default ='2 Months')
    completion_date = models.DateTimeField(null=True)
    amount = models.FloatField()
    target_amount = models.FloatField(null=True)
    status = models.CharField(max_length= 40,choices = WEEKLY_SAVE_STATUS_CHOICES, default='Pending')
    week_save_day = models.CharField(max_length =100, choices=WEEKLY_SAVE_DAY_CHOICES, default='Friday')
    amount_saved = models.FloatField()

我的表格。

class StartWeeklySaveForm(forms.ModelForm):

   title = forms.CharField(label = 'Savings Title', required=True)
   amount =  forms.FloatField(label='Amount to Save Weekly? (in Naira):', min_value=WeeklySaving.MIN_WEEKLY_SAVE, max_value=WeeklySaving.MAX_WEEKLY_SAVE, required=True, widget=forms.TextInput(attrs={'placeholder': 'Input the amount you want to save weekly. Minimum 500'}))

   class Meta:
       model = WeeklySaving
       fields = ["title", "amount", "duration", "week_save_day"]


class DepositWeeklySaveForm(forms.ModelForm):
       amount = forms.FloatField(label='Enter Amount in (Naira)', min_value=WeeklySaving.MIN_WEEKLY_SAVE, max_value=WeeklySaving.MAX_WEEKLY_SAVE, required=True, help_text='How much to deposit? Minimum 500',)
   dep_proof = forms.ImageField(label='Upload a Proof of Payment', help_text='teller or transaction receipt as image')

   class Meta:
       model = WeeklySavingsDeposit
       fields =["savings_title", "amount", "dep_proof"]

在我的 Views.py 我有這個

@login_required
def weekly_save(request):
    startwksave_form = StartWeeklySaveForm(request.POST or None, request.FILES)
    depwksave_form = DepositWeeklySaveForm(request.POST or None, request.FILES)
    user=request.user
    depwksave_form.fields['savings_title'] = WeeklySaveDepositModelChoiceField(WeeklySaving.objects.filter(user=user), empty_label="(Select savings)",required=True)
    depwksave_form.fields['amount'] = WeeklySaveDepositAmountModelChoiceField(WeeklySaving.objects.filter(user=user), empty_label="(Select savings amount)",required=True)

我有一個 fields.py 如下

from savings.models import WeeklySaving, WeeklySavingsDeposit
from django.forms import ModelChoiceField


class WeeklySaveDepositModelChoiceField(ModelChoiceField):
    def label_from_instance(self, obj):
        result = obj.title
        return str(result)


class WeeklySaveDepositAmountModelChoiceField(ModelChoiceField):
    def label_from_instance(self, obj):
        result = obj.amount
        return float(result)

在我的模板中，表單顯示如下..表單模板視圖

我可以從 WeeklySaving 對象中選擇儲蓄標題和金額，這是我想要的，但是當我提交表單時，它顯示錯誤“用戶名儲蓄”必須是浮點數。 這意味着它實際上是將輸入保存為“用戶名保存”而不是選擇的保存標題和金額。

我該如何解決這個問題，我需要幫助。 我還是新手，使用 django。

謝謝你的幫助。

Answer 1

一般來說，在同一個視圖中使用多個表單總是很困難。 因此，如果您將它們拆分為 2 個視圖，則會容易得多。 也許可以從另一個對象創建一個對象？ 更糟糕的是（我認為）兩種形式都有“金額”字段。 也許可以重命名其中之一。

另一個大問題是： DepositWeeklySaveForm().amount = forms.FloatField和這個depwksave_form.fields['amount'] = WeeklySaveDepositAmountModelChoiceField這行不通。 WeeklySaveDepositAmountModelChoiceField應引用 ForeginKey，而不是 FloatField。 所以添加到你的模型中：

class WeeklySavingsDeposit(models.Model):
    weekly_savings = models.ForeignKey(WeeklySaving, on_delete=models.CASCADE)
    ...

我建議將所有內容更改為基於類的視圖，例如CreateView並使用get_form_kwargs傳遞用戶。 就像是

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['user'] = self.request.user
        return kwargs

然后你可以像這樣在 forms.py 中設置字段：

class DepositWeeklySaveForm(forms.ModelForm):
    weekly_savings = forms.ModelMultipleChoiceField(queryset=None)
    required=True, help_text='How much to deposit? Minimum 500',)
   dep_proof = forms.ImageField(label='Upload a Proof of Payment', help_text='teller or transaction receipt as image')

   class Meta:
       model = WeeklySavingsDeposit
       fields =["savings_title", "amount", "dep_proof", "weekly_savings"]

    def __init__(self, user, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields['weekly_savings'].queryset = WeeklySaving.objects.filter(user=user)