NULL约束失败: Movies_comment.movie_id djnago

Question

我得到错误NULL约束失败: Movies_comment.movie_id。我试图返回模型类电影中评论和评分的平均值，但是我得到了错误NULL约束失败: Movies_comment.movie_id。我怎么才能修好它？

class Movie(models.Model):
    
    def get_comments(self):
        return Comment.objects.filter(movie_id=self.id)
    
    def average_stars(self):
        comments = self.get_comments()
        n_comments = comments.count()
        if n_comments == 0:
            return 0
        else:
            return sum([comment.stars for comment in comments]) / n_comments
    

class Comment(models.Model):
    comment     = models.TextField(max_length=1000)
    stars       = models.FloatField(
                     blank=False,
                     null=False,
                     default=0, 
                     validators=[MinValueValidator(0.0),
                     MaxValueValidator(10.0)]
                  )

    user        = models.OneToOneField(CustomUser, on_delete=models.CASCADE,)
    movie       = models.ForeignKey(Movie, on_delete=models.CASCADE)
    created_at  = models.DateTimeField(default=datetime.now)
    updated_at  = models.DateTimeField(auto_now=True)

def view_movie_detail(request, movie_id):
    if request.method == "POST":
        user = request.user  
        comment = request.POST.get("comment")
        stars = request.POST.get("stars")
        if not request.user.is_authenticated:
            user = User.objects.get(id=1)

        Comment(comment=comment, stars = stars, user=user,movie_id=movie_id).save()

        return redirect(f"/movie/{movie_id}/")
    else:
        data = requests.get(f"https://api.themoviedb.org/3/movie/{movie_id}?api_key={TMDB_API_KEY}&language=en-US")
        recommendations = requests.get(f"https://api.themoviedb.org/3/movie/{movie_id}/recommendations?api_key={TMDB_API_KEY}&language=en-US")
        comments = reversed(Movie().get_comments())
        average = Movie().average_stars()
        return render(request, "Movie/movie_detail.html", {
            "data": data.json(),
            "recommendations": recommendations.json(),
            "type": "movie",
            "comments": comments,
            "average" : average,
        })

上面的异常( NULL约束失败: Movies_comment.movie_id)是导致以下异常的直接原因：

Traceback:Traceback(最近一次调用)：文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\utils.py"，第98行，在内部返回函数(*args，**kwargs)

上述异常(外键约束失败)是以下异常的直接原因:文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\core\handlers\exception.py"，行55，内部响应=get_response(请求)文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\core\handlers\base.py"，行197，_get_response响应=wrapped_callback(请求，*callback_args，文件"C:\Users\81804\enviroment\MovieReview\MovieReview\Movies\views.py"，( **callback_kwargs)第74行，在view_movie_detail注释(comment=comment，stars = stars，user=user，movie_id=movie_id)中，文件user=user()user=user()在保存"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py"，(文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py"，行857，save_base self.save_base= self._save_table(文件“C：\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py”，行1000 )中，在"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py"，结果= self._do_insert(文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\manager.py"，行1041，_do_insert返回manager._insert(文件“C：\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\manager.py”，行85，manager_method返回getattr(self.get_queryset()，name))中(*args，**kwargs)文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\query.py"，第1434行，在_insert返回query.get_compiler(using=using).execute_sql(returning_fields)文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\sql\compiler.py"，第1632行，在self.connection.ops.fetch_returned_insert_columns(文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\backends\base\operations.py"，第205行中，在fetch_returned_insert_columns返回cursor.fetchone()文件第98行中，在内部返回函数(*args)中**kwargs)文件"C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\utils.py"，第91行，在出口中从exc_value File "C:\Users\81804\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\utils.py"，第98行提起dj_exc_value.with_traceback(回溯)，在内部返回函数(*args，**kwargs)

异常类型:/ IntegrityError /616037/异常值:外键约束失败

Answer 1

由于您没有提供追溯功能，导致这种错误的唯一地方是在这里：

Comment(comment=comment, stars = stars, user=user,movie_id=movie_id).save()

您正在创建新对象，但是变量movie_id似乎是空的(None)。您需要确保它以正确的方式传递到视图(如http://yourdomain.com/view_movie_detail/12/ )。