在表单中添加的字段上添加到 manytomany 字段

Question

我有一个模型，需要一个用户（ForeignKey）和一个类别（M2M），对于表单中的类别字段，我通过向其添加自定义字段来扩展其功能（数据列表但也有输入） ，但我无法使用类别和用户保存表单。

models.py

from django.contrib.auth.models import AbstractUser
from django.db import models


class User(AbstractUser):
    pass

class Category(models.Model):
    name = models.CharField(max_length=20, blank=True)

class Listings(models.Model):
    title = models.CharField(max_length=64, null=False, blank=False)
    description = models.CharField(max_length=64, blank=True)
    bid = models.IntegerField(null=False, blank=False)
    timestamp = models.DateField(db_index=True, auto_now_add=True)
    image_url = models.URLField(blank=True)
    category = models.ManyToManyField(Category)
    owner = models.ForeignKey(User, on_delete=models.CASCADE)

    class Meta:
        ordering=['timestamp', 'title']

forms.py

from auctions.models import Listings
from django import forms

class ListTextWidget(forms.TextInput):
    def __init__(self, data_list, name, *args, **kwargs):
        super(ListTextWidget,self).__init__(*args, **kwargs)
        self._name = name
        self._list = data_list
        self.attrs.update({
            'list':'list__%s' % self._name,
            'class':'form-control'
            })
    
    def render(self, name, value, attrs=None, renderer=None):
        text_html = super(ListTextWidget, self).render(name, value, attrs=attrs)
        data_list = '<datalist id="list__%s">' % self._name
        for item in self._list:
            data_list += '<option value="%s">' % item
        data_list += '</datalist>'

        return (text_html + data_list)


class ListingsForm(forms.ModelForm):
    category = forms.CharField()

    class Meta:
        model = Listings
        fields = ['title', 'description', 'bid', 'image_url', 'category']
        widgets = {
            'title': forms.TextInput(attrs={'class':'form-control'}),
            'description': forms.TextInput(attrs={'class':'form-control'}),
            'bid': forms.TextInput(attrs={'class':'form-control'}),
            'image_url': forms.TextInput(attrs={'class':'form-control'}),
            'category': forms.TextInput(attrs={'class':'form-control'})
        }
    def __init__(self, *args, **kwargs):
        _category_list = kwargs.pop('data_list', None)
        super(ListingsForm, self).__init__(*args, **kwargs)
    
        self.fields['category'].widget = ListTextWidget(data_list=_category_list, name='category-list')

views.py

def create_listings(request):
    if request.method == "POST":
        form = ListingsForm(request.POST)
        if form.is_valid():
            #**what to do to save category and user**
            return redirect(reverse('index'))
    else:
        category_list = Category.objects.all().values_list('name')
        form = ListingsForm(data_list=category_list)   
    return render(request, 'auctions/create_listings.html', {
        'form': form
    })

如何在 form.save() 期间将所有数据保存到新的列表中？

我尝试过使用 commit=False，但我得到了ValueError:Field 'id' expected a number but got 'o'. 有没有办法一次保存，还是必须创建一个列表，然后手动添加剩余的数据？

Answer 1

您可以尝试以下方法，将M2M字段更改为外键，然后在表单中没有太多更改，只需删除类别，最后在视图中保存后添加用户（提交=假） models.py

from django.contrib.auth.models import AbstractUser
from django.db import models


class User(AbstractUser):
    pass

class Category(models.Model):
    name = models.CharField(max_length=20, blank=True)
    
    
    def __str__(self) -> str:
        return self.name

class Listings(models.Model):
    title = models.CharField(max_length=64, null=False, blank=False)
    description = models.CharField(max_length=64, blank=True)
    bid = models.IntegerField(null=False, blank=False)
    timestamp = models.DateField(db_index=True, auto_now_add=True)
    image_url = models.TextField(blank=True)
    category = models.ForeignKey(Category, null=True, blank=True, on_delete=models.SET_NULL)
    owner = models.ForeignKey(User, verbose_name="owner", on_delete=models.CASCADE, related_name='owner')

    class Meta:
        ordering=['-timestamp', 'title']
    
    def __str__(self) -> str:
        return self.title

forms.py

from auctions.models import Biddings, Comments, Listings
from django import forms

class ListTextWidget(forms.TextInput):
    def __init__(self, data_list, name, *args, **kwargs):
        super(ListTextWidget,self).__init__(*args, **kwargs)
        self._name = name
        self._list = data_list
        self.attrs.update({
            'list':'list__%s' % self._name,
            'class':'form-control'
            })
    
    def render(self, name, value, attrs=None, renderer=None):
        text_html = super(ListTextWidget, self).render(name, value, attrs=attrs)
        data_list = '<datalist id="list__%s">' % self._name
        for item in self._list:
            data_list += '<option value="%s">' % item
        data_list += '</datalist>'

        return (text_html + data_list)


class ListingsForm(forms.ModelForm):
    category = forms.CharField()

    class Meta:
        model = Listings
        fields = ['title', 'description', 'bid', 'image_url']
        widgets = {
            'title': forms.TextInput(attrs={'class':'form-control'}),
            'description': forms.TextInput(attrs={'class':'form-control'}),
            'bid': forms.TextInput(attrs={'class':'form-control'}),
            'image_url': forms.TextInput(attrs={'class':'form-control'}),
            'category': forms.TextInput(attrs={'class':'form-control'})
        }
    def __init__(self, *args, **kwargs):
        _category_list = kwargs.pop('data_list', None)
        super(ListingsForm, self).__init__(*args, **kwargs)
    
        self.fields['category'].widget = ListTextWidget(data_list=_category_list, name='category-list')

views.py 在这里，我手动渲染了字段以进行澄清

def create_listings(request):
    if request.method == "POST":
        form = ListingsForm(request.POST)
        if form.is_valid():
            title = form.cleaned_data["title"]
            description = form.cleaned_data["description"]
            bid = form.cleaned_data["bid"]
            image_url = form.cleaned_data["image_url"]
            category, created = Category.objects.get_or_create(name = form.cleaned_data["category"])
            owner = request.user
            listing = Listings(
                title=title,
                description=description,
                bid=bid,
                image_url=image_url,
                owner=owner,  
                category=Category.objects.get(name = form.cleaned_data["category"])             
                )
            listing.save()
            messages.success(request, "Listing created succesfully")
            return redirect(reverse('index'))
    else:
        category_list = Category.objects.all().values_list('name')
        form = ListingsForm(data_list=category_list)   
    return render(request, 'auctions/create_listings.html', {
        'form': form
    })

我真的希望这有助于解决您的问题 :)。干杯