Improve speed of the ChallengeSolves API endpoint (#2046)

* Improve speed of the ChallengeSolves API (`/api/v1/challenges/[challenge_id]/solves`) endpoint

CHANGELOG.md

@@ -1,3 +1,7 @@
+# UNRELEASED
+
+- Improved speed of the `/api/v1/challenges/[challenge_id]/solves` endpoint
+
 # 3.4.0 / 2021-08-11
 
 **General**

CTFd/api/v1/challenges.py

@@ -764,8 +764,13 @@ class ChallengeSolves(Resource):
 
         Model = get_model()
 
+        # Note that we specifically query for the Solves.account.name
+        # attribute here because it is faster than having SQLAlchemy
+        # query for the attribute directly and it's unknown what the
+        # affects of changing the relationship lazy attribute would be
         solves = (
-            Solves.query.join(Model, Solves.account_id == Model.id)
+            Solves.query.add_columns(Model.name.label("account_name"))
+            .join(Model, Solves.account_id == Model.id)
             .filter(
                 Solves.challenge_id == challenge_id,
                 Model.banned == False,
@@ -782,10 +787,12 @@ class ChallengeSolves(Resource):
                 solves = solves.filter(Solves.date < dt)
 
         for solve in solves:
+            # Seperate out the account name and the Solve object from the SQLAlchemy tuple
+            solve, account_name = solve
             response.append(
                 {
                     "account_id": solve.account_id,
-                    "name": solve.account.name,
+                    "name": account_name,
                     "date": isoformat(solve.date),
                     "account_url": generate_account_url(account_id=solve.account_id),
                 }