在Django/DRF中实现文章访问/评论筛选及访问状态显示问题

一、修复序列化相关错误 #

1. 解决seen_by_user显示绑定方法的问题 #

在Article模型中定义判断用户是否查看过的方法，确保返回布尔值而非方法对象：

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

User = get_user_model()

class Article(models.Model):
    title = models.CharField(max_length=200)
    content = models.TextField()
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)

    def seen_by_user(self, user):
        if not user.is_authenticated:
            return False
        return ArticleSeenRecord.objects.filter(article=self, user=user).exists()

class ArticleSeenRecord(models.Model):
    article = models.ForeignKey(Article, on_delete=models.CASCADE, related_name='seen_records')
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    seen_at = models.DateTimeField(auto_now=True)

    class Meta:
        unique_together = ('article', 'user')  # 避免重复记录

2. 修复SerializerMethodField的NameError问题 #

在序列化器中通过obj参数获取当前文章实例，同时传入请求上下文获取用户：

from rest_framework import serializers
from .models import Article

class ArticleSerializer(serializers.ModelSerializer):
    seen_by_user = serializers.SerializerMethodField()

    class Meta:
        model = Article
        fields = ['id', 'title', 'content', 'author', 'created_at', 'seen_by_user']

    def get_seen_by_user(self, obj):
        # obj为当前Article实例，从上下文获取请求用户
        user = self.context['request'].user
        return obj.seen_by_user(user)

视图中序列化时必须传入请求上下文：

serializer = ArticleSerializer(articles, many=True, context={'request': request})

二、实现模板标签判断用户是否查看过文章 #

1. 在app目录下创建templatetags文件夹，新建article_tags.py：

from django import template
from ..models import ArticleSeenRecord

register = template.Library()

@register.filter(name='has_seen')
def has_seen(article, user):
    if not user.is_authenticated:
        return False
    return ArticleSeenRecord.objects.filter(article=article, user=user).exists()

2. 在模板中加载并使用标签：

{% load article_tags %}

{% for article in articles %}
    <div class="article-item">
        <h3>{{ article.title }}</h3>
        {% if user|has_seen:article %}
            <span class="tag">已查看</span>
        {% else %}
            <span class="tag">未查看</span>
        {% endif %}
    </div>
{% endfor %}

三、实现筛选最近访问/评论过的文章功能 #

1. 筛选最近访问的文章 #

def get_recent_seen_articles(user, limit=10):
    if not user.is_authenticated:
        return Article.objects.none()
    # 获取用户最近访问记录，按访问时间倒序
    seen_records = ArticleSeenRecord.objects.filter(user=user).order_by('-seen_at')[:limit]
    article_ids = [record.article.id for record in seen_records]
    # 保持访问顺序返回文章
    return Article.objects.filter(id__in=article_ids).order_by(
        models.Case(*[models.When(id=aid, then=pos) for pos, aid in enumerate(article_ids)])
    )

2. 筛选最近评论的文章 #

假设已有关联Article和User的Comment模型：

def get_recent_commented_articles(user, limit=10):
    if not user.is_authenticated:
        return Article.objects.none()
    # 获取用户最近评论记录，去重文章后按评论时间倒序
    comments = Comment.objects.filter(user=user).order_by('-created_at').distinct('article')[:limit]
    article_ids = [comment.article.id for comment in comments]
    return Article.objects.filter(id__in=article_ids).order_by(
        models.Case(*[models.When(id=aid, then=pos) for pos, aid in enumerate(article_ids)])
    )

3. 合并筛选访问/评论过的文章（去重并按最近操作时间排序） #

from django.db.models import Value, Case, When, F

def get_recent_interacted_articles(user, limit=10):
    if not user.is_authenticated:
        return Article.objects.none()
    
    articles = Article.objects.annotate(
        last_interacted_at=Case(
            When(seen_records__user=user, then=F('seen_records__seen_at')),
            When(comments__user=user, then=F('comments__created_at')),
            default=Value('1970-01-01'),
            output_field=models.DateTimeField()
        )
    ).filter(
        models.Q(seen_records__user=user) | models.Q(comments__user=user)
    ).distinct().order_by('-last_interacted_at')[:limit]
    
    return articles

内容的提问来源于stack exchange，提问作者Abdullah Roshan