基于外键筛选批量编辑Django现有Choice模型条目求助

Hey there! Let's get this sorted out for your Django 2.0.4 poll app. You're on the right track with modelformset—probably just missing a few key bits like filtering the formset to the specific Question and handling the foreign key association when saving. Here's a step-by-step working solution:

1. Confirm Your Model Setup (align with official tutorial) #

First, make sure your polls/models.py matches the base structure (adjust if you've modified it):

from django.db import models

class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

2. Create Choice Form & FormSet #

Create a polls/forms.py file (if it doesn't exist) to define your form and formset:

from django import forms
from django.forms import modelformset_factory
from .models import Choice

# Simple form for Choice - we only expose the editable field
class ChoiceForm(forms.ModelForm):
    class Meta:
        model = Choice
        fields = ['choice_text']

# Generate a formset with 2 extra empty fields for new options
ChoiceFormSet = modelformset_factory(
    Choice,
    form=ChoiceForm,
    extra=2,
    can_delete=False  # Remove this line if you want to let users delete options
)

3. Build the Login-Protected View #

Add this view to polls/views.py to handle editing choices for a specific Question:

from django.shortcuts import get_object_or_404, render, redirect
from django.contrib.auth.decorators import login_required
from .models import Question
from .forms import ChoiceFormSet

@login_required
def edit_choices(request, pk):
    # Fetch the target Question instance
    question = get_object_or_404(Question, pk=pk)
    
    if request.method == 'POST':
        # Initialize formset with POST data, filtered to this Question's choices
        formset = ChoiceFormSet(
            request.POST,
            queryset=Choice.objects.filter(question=question)
        )
        if formset.is_valid():
            # Save each form, ensuring the foreign key links to the current Question
            for form in formset:
                if form.cleaned_data:  # Skip empty extra forms the user didn't fill
                    choice = form.save(commit=False)
                    choice.question = question
                    choice.save()
            # Redirect back to the edit page (or to your question detail page)
            return redirect('polls:edit_choices', pk=pk)
    else:
        # Load existing choices for the Question on GET request
        formset = ChoiceFormSet(queryset=Choice.objects.filter(question=question))
    
    return render(request, 'polls/edit_choices.html', {
        'question': question,
        'formset': formset
    })

4. Update Your URL Configuration #

Add this pattern to polls/urls.py:

from django.urls import path
from . import views

app_name = 'polls'
urlpatterns = [
    # ... your existing URLs ...
    path('question/<int:pk>/edit-choices/', views.edit_choices, name='edit_choices'),
]

5. Create the Edit Template #

Make polls/templates/polls/edit_choices.html to render the formset:

<!DOCTYPE html>
<html>
<head>
    <title>Edit Choices: {{ question.question_text }}</title>
</head>
<body>
    <h1>Edit Choices for "{{ question.question_text }}"</h1>
    
    <form method="post">
        {% csrf_token %}
        {{ formset.management_form }}  <!-- DO NOT OMIT THIS - critical for formset functionality -->
        
        {% for form in formset %}
            <div style="margin: 10px 0;">
                {{ form.id }}  <!-- Hidden field to track existing forms -->
                <label>Option {{ forloop.counter }}:</label>
                {{ form.choice_text }}
                {% if form.errors %}
                    <span style="color: red; margin-left: 10px;">{{ form.choice_text.errors }}</span>
                {% endif %}
            </div>
        {% endfor %}
        
        <button type="submit">Save Changes</button>
    </form>
    
    <p style="margin-top: 20px;"><a href="{% url 'polls:detail' question.id %}">Back to Question</a></p>
</body>
</html>

Key Tips to Avoid Pitfalls: #

• Never skip formset.management_form: This hidden form contains metadata Django needs to process the formset correctly (like how many forms exist). Omitting it will throw errors.
• Filter the queryset: By limiting the formset to the current Question's choices, you ensure you're only editing options tied to that specific question.
• Skip empty extra forms: The if form.cleaned_data check prevents saving blank options if the user doesn't fill out the extra fields.
• Login protection: The @login_required decorator enforces your requirement that only logged-in users can access this page.

Test it out by navigating to /polls/question/<your-question-pk>/edit-choices/ after logging in—you'll see existing choices plus 2 empty fields to add new options. All edits and new choices will be saved to the correct Question.

内容的提问来源于stack exchange，提问作者johntkrpt