如何解决Django影评提交与更新功能中的IntegrityError问题

Hey there, let's figure out why your review form is throwing those errors and fix it up.

First, let's unpack the error messages:

• The first reviews.DoesNotExist makes sense—it just means the user hasn't submitted a review for this movie yet, so your get() call can't find an existing record.
• The real problem comes in the except block: when you create a new reviews instance, you're not setting the movie and user fields. Since these are required ForeignKeys in your model, the database rejects the save because movie_id (and user_id) can't be null.

Here's how to fix this, step by step:

1. Fix the new review creation in the except block #

You need to associate the new review with both the current movie and the logged-in user. Update your views.py code like this:

First, make sure you import the necessary modules (if you haven't already):

from django.core.exceptions import ObjectDoesNotExist
from .models import reviews, details  # Ensure details is your Movie model
from django.contrib.auth.decorators import login_required

Then modify the user_reviews view:

@login_required  # Add this to ensure only logged-in users can submit reviews
def user_reviews(request, movies_id):
    url = request.META.get('HTTP_REFERER')
    if request.method == 'POST':
        try:
            # Try to get existing review for this user and movie
            ureview = reviews.objects.get(movie__id=movies_id, user__id=request.user.id)
            form = ReviewForm(request.POST, instance=ureview)
            form.save()
            return redirect(url)
        except ObjectDoesNotExist:
            form = ReviewForm(request.POST)
            if form.is_valid():
                data = reviews()
                # Set the required ForeignKey fields (this fixes the null error)
                data.movie = details.objects.get(id=movies_id)  # Link to the correct movie
                data.user = request.user  # Link to the logged-in user
                # Set the other fields from the form
                data.title = form.cleaned_data['title']
                data.review = form.cleaned_data['review']
                data.rating = form.cleaned_data['rating']
                data.ip = request.META.get('REMOTE_ADDR')
                data.save()
                return redirect(url)
    # Add handling for GET requests (when user first loads the page)
    else:
        # Optionally pre-fill form if user has an existing review
        try:
            existing_review = reviews.objects.get(movie__id=movies_id, user__id=request.user.id)
            form = ReviewForm(instance=existing_review)
        except ObjectDoesNotExist:
            form = ReviewForm()
        return render(request, 'your_review_template.html', {'form': form, 'movies_id': movies_id})

2. Why this works: #

• @login_required ensures request.user is always a valid logged-in user, preventing issues with anonymous users trying to submit reviews.
• We explicitly set data.movie to the details object matching movies_id, and data.user to request.user. This populates the required movie_id and user_id fields in the database, fixing the IntegrityError.
• Added handling for GET requests—your original code didn't account for this, which could lead to unexpected behavior when users first navigate to the review page.

Bonus: Use ModelForm for cleaner code #

Your ReviewForm should probably be a ModelForm, which simplifies creating/updating instances without manually assigning fields. Here's how that would look:

In forms.py:

from django import forms
from .models import reviews

class ReviewForm(forms.ModelForm):
    class Meta:
        model = reviews
        fields = ['title', 'review', 'rating']  # Fields users can edit

Then your view can be simplified even more:

@login_required
def user_reviews(request, movies_id):
    url = request.META.get('HTTP_REFERER')
    movie = details.objects.get(id=movies_id)  # Get the movie once
    try:
        existing_review = reviews.objects.get(movie=movie, user=request.user)
    except ObjectDoesNotExist:
        existing_review = None

    if request.method == 'POST':
        form = ReviewForm(request.POST, instance=existing_review)
        if form.is_valid():
            review = form.save(commit=False)
            review.movie = movie
            review.user = request.user
            review.ip = request.META.get('REMOTE_ADDR')
            review.save()
            return redirect(url)
    else:
        form = ReviewForm(instance=existing_review)
    
    return render(request, 'your_review_template.html', {'form': form, 'movie': movie})

This version is cleaner, less error-prone, and follows Django best practices.

Final Checks: #

• Confirm your details model is correctly imported in views.py.
• Ensure your template is passing the correct movies.id to the form's action URL (your existing HTML looks okay for this).
• Test both submitting a new review and updating an existing one to confirm the fix works.

内容的提问来源于stack exchange，提问作者Abin Benny