QuizContext: Keep just the last answer, not the entire history

Author: janezd

api/quiz.ts

@@ -170,7 +170,7 @@ export const postFileAnswer = async (
 
 export type CorrectAnswers = { questionId: string, answer: string }[];
 
-export const getAnswers = async ({ accessToken, bookId, group }: {
+export const getLastAnswers = async ({ accessToken, bookId, group }: {
   accessToken: string;
   bookId: number;
   group: string | undefined | null;
@@ -179,37 +179,46 @@ export const getAnswers = async ({ accessToken, bookId, group }: {
   const answers = [
     ...(
       await db.all(`
-        SELECT answers.answer, q.questionId, isCorrect, points
-        FROM answers
-        JOIN questions q ON answers.questionId = q.id
-        LEFT JOIN groups g ON answers.groupId = g.id
-        WHERE userId = ? AND bookId = ? AND g.name IS ? AND q.type NOT LIKE 'upload%'
-        ORDER BY answers.createdAt`,
+        SELECT answer, questionId, isCorrect, points, nAttempts FROM (
+          SELECT a.answer, q.questionId, a.isCorrect, a.points,
+                 ROW_NUMBER() OVER (PARTITION BY a.questionId ORDER BY a.createdAt DESC) AS rn,
+                 COUNT(*) OVER (PARTITION BY a.questionId) AS nAttempts
+          FROM answers a
+          JOIN questions q ON a.questionId = q.id
+          LEFT JOIN groups g ON a.groupId = g.id
+          WHERE a.userId = ? AND a.bookId = ? AND g.name IS ? AND q.type NOT LIKE 'upload%'
+        ) t
+        WHERE rn = 1;`,
         [userId, bookId, group ?? null]
-      )).map(({answer, questionId, isCorrect, points}) => ({
+      )).map(({answer, questionId, isCorrect, points, nAttempts}) => ({
         type: "value",
         answer,
         questionId,
         points,
+        nAttempts,
         // DB stores 0 and 1 even if the column is declared as BOOLEAN
         isCorrect: isCorrect === null ? undefined : !!isCorrect,
-      }) as AnswerValue & {questionId: string}),
+      }) as AnswerValue & {questionId: string, nAttempts: number}),
     ...(
       await db.all(`
-        SELECT q.questionId, group_concat(u.filename, "\n") as files
-        FROM answers
-        JOIN questions q ON answers.questionId = q.id
-        LEFT JOIN groups g ON answers.groupId = g.id
-        LEFT JOIN uploads u ON u.answerId = answers.id
-        WHERE userId = ? AND bookId = ? AND g.name IS ? AND q.type LIKE 'upload%'
-        GROUP BY answers.id
-        ORDER BY answers.createdAt`,
+        SELECT questionId, group_concat(u.filename, "\n") as files, 1 as nAttempts FROM (
+          SELECT q.questionId, a.id as answerId,
+                 ROW_NUMBER() OVER (PARTITION BY a.questionId ORDER BY a.createdAt DESC) AS rn
+          FROM answers a
+          JOIN questions q ON a.questionId = q.id
+          LEFT JOIN groups g ON a.groupId = g.id
+          WHERE userId = ? AND bookId = ? AND g.name IS ? AND q.type LIKE 'upload%'
+        ) t
+        JOIN uploads u ON u.answerId = t.answerId
+        WHERE rn = 1
+        GROUP BY t.answerId;`,
         [userId, bookId, group ?? null]
-      )).map(({files, questionId}) => ({
+      )).map(({files, questionId, nAttempts}) => ({
         type: "files",
         questionId,
+        nAttempts,
         files: files ? files.split("\n") : [],
-      }) as AnswerFile & {questionId: string})
+      }) as AnswerFile & {questionId: string, nAttempts: number})
   ];
 
   const correctAnswers =

components/Book/Book.tsx

@@ -5,14 +5,14 @@ import { usePathname } from "next/navigation";
 import Image from "../Image";
 import { toast } from "react-toastify";
 
-import { AnswersInBook, CorrectAnswers, getAnswers, getAnswersInBook } from "@/api/quiz";
+import { AnswersInBook, CorrectAnswers, getLastAnswers, getAnswersInBook } from "@/api/quiz";
 import { BookProps, getPublicCollection } from "@/api/book";
 import { isAdminFor } from "@/api/user";
 
 import { logger } from "@/utils/logger";
 import { getT, IntlContextProvider } from "@/i18n";
 import { UserContext } from "@/context/UserContextProvider";
-import { AnswerWithQuestionId, QuizContextProvider } from "@/context/QuizContextProvider";
+import { AnswerState, QuizContextProvider } from "@/context/QuizContextProvider";
 import Layout from "../Layout/Layout";
 
 import Login from "../Login";
@@ -34,7 +34,7 @@ export const Book = (
   const [ isAdmin, setIsAdmin ] = useState<boolean>(false);
   const [answers, setAnswers] =
     useState<"pending" | null | {
-      answers: AnswerWithQuestionId[],
+      answers: AnswerState[],
       correctAnswers: CorrectAnswers}>("pending");
   const hasGroups = useMemo(() => frontmatter.groups.length > 0, [frontmatter]);
   const [groupRequired, setGroupRequired] = useState<boolean | null>(null);
@@ -56,7 +56,7 @@ export const Book = (
     ) {
       return;
     }
-    getAnswers({ accessToken: user.accessToken, bookId, group: userGroup})
+    getLastAnswers({ accessToken: user.accessToken, bookId, group: userGroup})
       .then((response) => {
         logger("Quiz answers fetched:", response);
         setAnswers(response);