优化Django DetailView浏览计数：避免重复递增与使用F()表达式

from django.views.generic import DetailView

class MovieDetail(DetailView):
    model = Movie

    def get_object(self):
        # 错误示例：在此处递增计数
        obj = super().get_object()
        obj.views_count += 1
        obj.save()
        return obj

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # 潜在问题：这里可能会再次调用 get_object()
        # 例如：context['links'] = MovieLink.objects.filter(movie=self.get_object())
        # 例如：context['related_movies'] = Movie.objects.filter(category=self.get_object().category)
        return context

from django.views.generic import DetailView
# from django.db.models import F # 稍后会用到 F() 表达式

class MovieDetail(DetailView):
    model = Movie

    # 保持 get_object() 纯粹，只负责获取对象
    # def get_object(self):
    #     return super().get_object()

    def render_to_response(self, context, **response_kwargs):
        # 在这里递增计数，确保只执行一次
        self.object.views_count += 1
        self.object.save()
        return super().render_to_response(context, **response_kwargs)

    # get_context_data 保持不变，但不再需要调用 self.get_object()
    # 因为 self.object 已经在 DetailView 内部被设置
    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # 直接使用 self.object
        context['links'] = MovieLink.objects.filter(movie=self.object)
        context['related_movies'] = Movie.objects.filter(category=self.object.category)
        return context

from django.views.generic import DetailView
from django.db.models import F # 导入 F() 表达式

class MovieDetail(DetailView):
    model = Movie

    def render_to_response(self, context, **response_kwargs):
        # 使用 F() 表达式进行原子性递增
        self.object.views_count = F('views_count') + 1
        self.object.save() # 这会将 F() 表达式的变更应用到数据库

        # 刷新对象以获取最新的 views_count 值（如果需要在模板中显示更新后的值）
        # self.object.refresh_from_db() # 仅当需要在当前请求的模板中显示更新后的值时才需要

        return super().render_to_response(context, **response_kwargs)

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # 直接使用 self.object，无需再次调用 get_object()
        context['links'] = MovieLink.objects.filter(movie=self.object)
        context['related_movies'] = Movie.objects.filter(category=self.object.category)
        return context

from django.views.generic import DetailView
from django.db.models import F

class MovieDetail(DetailView):
    model = Movie
    template_name = 'movie_detail.html' # 假设你的模板文件

    # get_object() 保持默认行为，只负责获取对象
    # def get_object(self, queryset=None):
    #     return super().get_object(queryset)

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # 直接使用 self.object，避免重复调用 get_object()
        context['links'] = MovieLink.objects.filter(movie=self.object)
        context['related_movies'] = Movie.objects.filter(category=self.object.category)
        return context

    def render_to_response(self, context, **response_kwargs):
        # 1. 使用 F() 表达式原子性递增 views_count
        self.object.views_count = F('views_count') + 1
        self.object.save(update_fields=['views_count']) # 仅更新 views_count 字段，提高效率

        # 2. (可选) 如果模板需要显示更新后的 views_count，则刷新对象
        # self.object.refresh_from_db(fields=['views_count'])

        # 3. 返回父类的响应
        return super().render_to_response(context, **response_kwargs)

<section class="movie">
    <img src="{{ object.image.url }}">
    <ul>
        <li>{{ object }}</li>
        <li>{{ object.description }}</li>
        <li><a href="genre.html">Adventure</a>, <a href="genre.html">Drama</a>, <a href="genre.html">Romance</a></li>
        <li><a href="">{{ object.cast }}</a></li>
        <li><i class="fa fa-eye" id="eye"></i> {{ object.views_count }}</li>
    </ul>
</section>