feat(reaction): 新增 reaction app 与数据模型

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

oj/settings.py

@@ -55,6 +55,7 @@ LOCAL_APPS = [
     "judge",
     "message",
     "comment",
+    "reaction",
     "tutorial",
     "ai",
     "flowchart",

reaction/migrations/0001_initial.py

@@ -0,0 +1,33 @@
+# Generated by Django 6.0.4 on 2026-08-06 07:35
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('problem', '0014_problem_tag_ci_unique'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Reaction',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('type', models.CharField(choices=[('too_easy', '太简单'), ('too_hard', '太难了'), ('confusing', '没看懂'), ('buggy', '题目有错'), ('learned', '学到了'), ('interesting', '有意思'), ('want_explain', '想听讲解')], max_length=20, verbose_name='表情类型')),
+                ('create_time', models.DateTimeField(auto_now_add=True)),
+                ('problem', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='problem.problem')),
+                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+            ],
+            options={
+                'db_table': 'reaction',
+                'indexes': [models.Index(fields=['problem', 'type'], name='reaction_problem_type_idx')],
+                'unique_together': {('problem', 'user', 'type')},
+            },
+        ),
+    ]

reaction/models.py

@@ -0,0 +1,28 @@
+from django.db import models
+
+from account.models import User
+from problem.models import Problem
+
+
+class ReactionType(models.TextChoices):
+    TOO_EASY = "too_easy", "太简单"
+    TOO_HARD = "too_hard", "太难了"
+    CONFUSING = "confusing", "没看懂"
+    BUGGY = "buggy", "题目有错"
+    LEARNED = "learned", "学到了"
+    INTERESTING = "interesting", "有意思"
+    WANT_EXPLAIN = "want_explain", "想听讲解"
+
+
+class Reaction(models.Model):
+    problem = models.ForeignKey(Problem, on_delete=models.CASCADE)
+    user = models.ForeignKey(User, on_delete=models.CASCADE)
+    type = models.CharField(max_length=20, choices=ReactionType.choices, verbose_name="表情类型")
+    create_time = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        db_table = "reaction"
+        unique_together = ("problem", "user", "type")
+        indexes = [
+            models.Index(fields=["problem", "type"], name="reaction_problem_type_idx"),
+        ]

reaction/serializers.py

@@ -0,0 +1,18 @@
+from reaction.models import ReactionType
+from utils.api import serializers
+
+MAX_REACTIONS = 3
+
+
+class SetReactionSerializer(serializers.Serializer):
+    problem_id = serializers.IntegerField()
+    types = serializers.ListField(
+        child=serializers.ChoiceField(choices=ReactionType.choices),
+        allow_empty=True,
+    )
+
+    def validate_types(self, value):
+        unique = list(dict.fromkeys(value))
+        if len(unique) > MAX_REACTIONS:
+            raise serializers.ValidationError(f"最多只能选 {MAX_REACTIONS} 个")
+        return unique

utils/constants.py

@@ -18,6 +18,7 @@ class CacheKey:
     problem_authors = "problem_authors"
     problem_tags = "problem_tags"
     comment_stats = "comment_stats"
+    reaction_stats = "reaction_stats"
     user_activity_rank = "user_activity_rank"
     problem_yearly_ac = "problem_yearly_ac"