fix

reaction/services.py

@@ -0,0 +1,19 @@
+from django.db.models import Count
+
+from reaction.models import Reaction, ReactionType
+
+# 并列票数时按 ReactionType 的定义顺序取靠前的那个，跟前端 REACTIONS 的顺序一致
+TYPE_ORDER = {t.value: index for index, t in enumerate(ReactionType)}
+
+
+def get_top_reactions(problem_ids):
+    """返回 {problem_id: {"type": ..., "count": ...}}，只包含有评价的题目。"""
+    if not problem_ids:
+        return {}
+    top = {}
+    rows = Reaction.objects.filter(problem_id__in=problem_ids).values("problem_id", "type").annotate(count=Count("id"))
+    for row in rows:
+        current = top.get(row["problem_id"])
+        if current is None or (-row["count"], TYPE_ORDER[row["type"]]) < (-current["count"], TYPE_ORDER[current["type"]]):
+            top[row["problem_id"]] = {"type": row["type"], "count": row["count"]}
+    return top