Question

我在这个网站上搜索了很多并找到了我的部分问题，但这个我找不到。也许我没有使用正确的关键字，这是一个常见问题吗？如果是这样的道歉。

我正在尝试将名为barcode_input的输入值与名为barcode的模型字段的表单进行匹配。如果匹配，则打印（“有匹配！”）将显示在终端中。

下一步将是，当匹配时，必须将amount_input值添加到特定模型已售出字段（与之匹配）并从特定模型amount_sold字段中减去（使用该字段时）一场比赛）。

到目前为止，这是我的代码。

models.py

from django.db import models

class AddProduct(models.Model):
    title = models.CharField(max_length=255)
    barcode = models.IntegerField(default=0, primary_key=True)
    stock_amount = models.IntegerField(default=0)
    sold = models.IntegerField(default=0)

    def __str__(self):
        return self.title

    class Meta:
        verbose_name_plural = "Products"

forms.py

from django import forms
from .models import AddProduct

class ScanProductForm(forms.Form):
    barcode_input = forms.IntegerField(label='scan barcode')
    amount_input = forms.IntegerField(label='amount')
    def clean(self):
        cleaned_data = super(ScanProductForm, self).clean()
        barcode_input = cleaned_data.get("barcode_input")
        amount_input = cleaned_data.get("amount_input")

        try:
            p = AddProduct.objects.get(pk=barcode_input)
            p.sold += amount_input
        except AddProduct.DoesNotExist:
            raise forms.ValidationError("Does not exist")

views.py

from django.shortcuts import render
from .forms import ScanProductForm

from .models import AddProduct

def scan_product_view(request):
    if request.method == 'POST':

        form = ScanProductForm(request.POST or None)

        if form.is_valid():
                print("There is a match!")
        else:
            form = ScanProductForm()

        return render(request, 'scanapp/barscan.html', {'form': form})

Answer 1

你应该使用Django的F表达式进行这类工作的 forms.py

from django.db.models import F from django import forms from .models import AddProduct class ScanProductForm(forms.Form): barcode_input = forms.IntegerField(label='scan barcode') amount_input = forms.IntegerField(label='amount') def clean(self): cleaned_data = super(ScanProductForm, self).clean() barcode_input = cleaned_data.get("barcode_input") amount_input = cleaned_data.get("amount_input") try: p = AddProduct.objects.get(pk=barcode_input) p.sold = F('sold') + amount_input p.save() except AddProduct.DoesNotExist: raise forms.ValidationError("Does not exist")

更好的方法是仅验证forms.py中的条形码输入字段并将更新对象的逻辑移到views.py。

的 forms.py

class ScanProductForm(forms.Form): barcode_input = forms.IntegerField(label='scan barcode') amount_input = forms.IntegerField(label='amount') def clean_barcode_input(self): barcode_input = self.cleaned_data['barcode_input'] qs = AddProduct.objects.filter(pk=barcode_input) if qs.exists(): return barcode_input raise forms.ValidationError("Barcode does not exist")

<强> views.py

from django.shortcuts import render from django.db.models import F from .forms import ScanProductForm from .models import AddProduct def scan_product_view(request): if request.method == 'POST': form = ScanProductForm(request.POST or None) if form.is_valid(): print("There is a match!") barcode_input = form.cleaned_data.get("barcode_input") amount_input = form.cleaned_data.get("amount_input") p = AddProduct.objects.get(pk=barcode_input) p.sold = F("sold") + amount_input p.save() else: form = ScanProductForm() return render(request, 'scanapp/barscan.html', {'form': form})

当输入与Django中的行匹配时，如何更改现有数据库中的值

1 个答案: