Merge pull request #171 from SELab-2/feat/question-routes

feat: Question en Answer routes

backend/src/config.ts

@@ -5,3 +5,4 @@ export const DWENGO_API_BASE = getEnvVar(envVars.LearningContentRepoApiBaseUrl);
 export const FALLBACK_LANG = getEnvVar(envVars.FallbackLanguage);
 
 export const FALLBACK_SEQ_NUM = 1;
+export const FALLBACK_VERSION_NUM = 1;

backend/src/controllers/answers.ts

@@ -0,0 +1,99 @@
+import { Request, Response } from 'express';
+import { requireFields } from './error-helper.js';
+import { getLearningObjectId, getQuestionId } from './questions.js';
+import { createAnswer, deleteAnswer, getAnswer, getAnswersByQuestion, updateAnswer } from '../services/answers.js';
+import { FALLBACK_SEQ_NUM } from '../config.js';
+import { AnswerData } from '@dwengo-1/common/interfaces/answer';
+
+export async function getAllAnswersHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const full = req.query.full === 'true';
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const answers = await getAnswersByQuestion(questionId, full);
+
+    res.json({ answers });
+}
+
+export async function getAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const seqAnswer = req.params.seqAnswer;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
+    const answer = await getAnswer(questionId, sequenceNumber);
+
+    res.json({ answer });
+}
+
+export async function createAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const author = req.body.author as string;
+    const content = req.body.content as string;
+    requireFields({ author, content });
+
+    const answerData = req.body as AnswerData;
+
+    const answer = await createAnswer(questionId, answerData);
+
+    res.json({ answer });
+}
+
+export async function deleteAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const seqAnswer = req.params.seqAnswer;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
+    const answer = await deleteAnswer(questionId, sequenceNumber);
+
+    res.json({ answer });
+}
+
+export async function updateAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const seqAnswer = req.params.seqAnswer;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const content = req.body.content as string;
+    requireFields({ content });
+
+    const answerData = req.body as AnswerData;
+
+    const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
+    const answer = await updateAnswer(questionId, sequenceNumber, answerData);
+
+    res.json({ answer });
+}

backend/src/controllers/learning-objects.ts

@@ -6,9 +6,9 @@ import attachmentService from '../services/learning-objects/attachment-service.j
 import { BadRequestException } from '../exceptions/bad-request-exception.js';
 import { NotFoundException } from '../exceptions/not-found-exception.js';
 import { envVars, getEnvVar } from '../util/envVars.js';
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
-function getLearningObjectIdentifierFromRequest(req: Request): LearningObjectIdentifier {
+function getLearningObjectIdentifierFromRequest(req: Request): LearningObjectIdentifierDTO {
     if (!req.params.hruid) {
         throw new BadRequestException('HRUID is required.');
     }

backend/src/controllers/questions.ts

@@ -1,34 +1,20 @@
 import { Request, Response } from 'express';
-import { createQuestion, deleteQuestion, getAllQuestions, getAnswersByQuestion, getQuestion } from '../services/questions.js';
-import { FALLBACK_LANG, FALLBACK_SEQ_NUM } from '../config.js';
+import { createQuestion, deleteQuestion, getAllQuestions, getQuestion, updateQuestion } from '../services/questions.js';
+import { FALLBACK_LANG, FALLBACK_SEQ_NUM, FALLBACK_VERSION_NUM } from '../config.js';
 import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
-import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
+import { QuestionData, QuestionId } from '@dwengo-1/common/interfaces/question';
 import { Language } from '@dwengo-1/common/util/language';
+import { requireFields } from './error-helper.js';
 
-function getObjectId(req: Request, res: Response): LearningObjectIdentifier | null {
-    const { hruid, version } = req.params;
-    const lang = req.query.lang;
-
-    if (!hruid || !version) {
-        res.status(400).json({ error: 'Missing required parameters.' });
-        return null;
-    }
-
+export function getLearningObjectId(hruid: string, version: string, lang: string): LearningObjectIdentifier {
     return {
         hruid,
-        language: (lang as Language) || FALLBACK_LANG,
-        version: Number(version),
+        language: (lang || FALLBACK_LANG) as Language,
+        version: Number(version) || FALLBACK_VERSION_NUM,
     };
 }
 
-function getQuestionId(req: Request, res: Response): QuestionId | null {
-    const seq = req.params.seq;
-    const learningObjectIdentifier = getObjectId(req, res);
-
-    if (!learningObjectIdentifier) {
-        return null;
-    }
-
+export function getQuestionId(learningObjectIdentifier: LearningObjectIdentifier, seq: string): QuestionId {
     return {
         learningObjectIdentifier,
         sequenceNumber: seq ? Number(seq) : FALLBACK_SEQ_NUM,
@@ -36,84 +22,84 @@ function getQuestionId(req: Request, res: Response): QuestionId | null {
 }
 
 export async function getAllQuestionsHandler(req: Request, res: Response): Promise<void> {
-    const objectId = getObjectId(req, res);
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
     const full = req.query.full === 'true';
+    requireFields({ hruid });
 
-    if (!objectId) {
-        return;
-    }
+    const learningObjectId = getLearningObjectId(hruid, version, language);
 
-    const questions = await getAllQuestions(objectId, full);
+    const questions = await getAllQuestions(learningObjectId, full);
 
-    if (!questions) {
-        res.status(404).json({ error: `Questions not found.` });
-    } else {
-        res.json({ questions: questions });
-    }
+    res.json({ questions });
 }
 
 export async function getQuestionHandler(req: Request, res: Response): Promise<void> {
-    const questionId = getQuestionId(req, res);
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
 
-    if (!questionId) {
-        return;
-    }
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
 
     const question = await getQuestion(questionId);
 
-    if (!question) {
-        res.status(404).json({ error: `Question not found.` });
-    } else {
-        res.json(question);
-    }
-}
-
-export async function getQuestionAnswersHandler(req: Request, res: Response): Promise<void> {
-    const questionId = getQuestionId(req, res);
-    const full = req.query.full === 'true';
-
-    if (!questionId) {
-        return;
-    }
-
-    const answers = await getAnswersByQuestion(questionId, full);
-
-    if (!answers) {
-        res.status(404).json({ error: `Questions not found` });
-    } else {
-        res.json({ answers: answers });
-    }
+    res.json({ question });
 }
 
 export async function createQuestionHandler(req: Request, res: Response): Promise<void> {
-    const questionDTO = req.body as QuestionDTO;
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    requireFields({ hruid });
 
-    if (!questionDTO.learningObjectIdentifier || !questionDTO.author || !questionDTO.content) {
-        res.status(400).json({ error: 'Missing required fields: identifier and content' });
-        return;
-    }
+    const loId = getLearningObjectId(hruid, version, language);
 
-    const question = await createQuestion(questionDTO);
+    const author = req.body.author as string;
+    const content = req.body.content as string;
+    requireFields({ author, content });
 
-    if (!question) {
-        res.status(400).json({ error: 'Could not create question' });
-    } else {
-        res.json(question);
-    }
+    const questionData = req.body as QuestionData;
+
+    const question = await createQuestion(loId, questionData);
+
+    res.json({ question });
 }
 
 export async function deleteQuestionHandler(req: Request, res: Response): Promise<void> {
-    const questionId = getQuestionId(req, res);
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
 
-    if (!questionId) {
-        return;
-    }
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
 
     const question = await deleteQuestion(questionId);
 
-    if (!question) {
-        res.status(400).json({ error: 'Could not find nor delete question' });
-    } else {
-        res.json(question);
-    }
+    res.json({ question });
+}
+
+export async function updateQuestionHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const content = req.body.content as string;
+    requireFields({ content });
+
+    const questionData = req.body as QuestionData;
+
+    const question = await updateQuestion(questionId, questionData);
+
+    res.json({ question });
 }

backend/src/data/questions/answer-repository.ts

@@ -2,6 +2,7 @@ import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
 import { Answer } from '../../entities/questions/answer.entity.js';
 import { Question } from '../../entities/questions/question.entity.js';
 import { Teacher } from '../../entities/users/teacher.entity.js';
+import { Loaded } from '@mikro-orm/core';
 
 export class AnswerRepository extends DwengoEntityRepository<Answer> {
     public async createAnswer(answer: { toQuestion: Question; author: Teacher; content: string }): Promise<Answer> {
@@ -19,10 +20,21 @@ export class AnswerRepository extends DwengoEntityRepository<Answer> {
             orderBy: { sequenceNumber: 'ASC' },
         });
     }
+    public async findAnswer(question: Question, sequenceNumber: number): Promise<Loaded<Answer> | null> {
+        return this.findOne({
+            toQuestion: question,
+            sequenceNumber,
+        });
+    }
     public async removeAnswerByQuestionAndSequenceNumber(question: Question, sequenceNumber: number): Promise<void> {
         return this.deleteWhere({
             toQuestion: question,
             sequenceNumber: sequenceNumber,
         });
     }
+    public async updateContent(answer: Answer, newContent: string): Promise<Answer> {
+        answer.content = newContent;
+        await this.save(answer);
+        return answer;
+    }
 }

backend/src/data/questions/question-repository.ts

@@ -3,6 +3,7 @@ import { Question } from '../../entities/questions/question.entity.js';
 import { LearningObjectIdentifier } from '../../entities/content/learning-object-identifier.js';
 import { Student } from '../../entities/users/student.entity.js';
 import { LearningObject } from '../../entities/content/learning-object.entity.js';
+import { Loaded } from '@mikro-orm/core';
 
 export class QuestionRepository extends DwengoEntityRepository<Question> {
     public async createQuestion(question: { loId: LearningObjectIdentifier; author: Student; content: string }): Promise<Question> {
@@ -61,4 +62,19 @@ export class QuestionRepository extends DwengoEntityRepository<Question> {
             orderBy: { timestamp: 'DESC' }, // New to old
         });
     }
+
+    public async findByLearningObjectAndSequenceNumber(loId: LearningObjectIdentifier, sequenceNumber: number): Promise<Loaded<Question> | null> {
+        return this.findOne({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            sequenceNumber,
+        });
+    }
+
+    public async updateContent(question: Question, newContent: string): Promise<Question> {
+        question.content = newContent;
+        await this.save(question);
+        return question;
+    }
 }

backend/src/interfaces/answer.ts

@@ -1,14 +1,14 @@
-import { mapToUserDTO } from './user.js';
 import { mapToQuestionDTO, mapToQuestionDTOId } from './question.js';
 import { Answer } from '../entities/questions/answer.entity.js';
 import { AnswerDTO, AnswerId } from '@dwengo-1/common/interfaces/answer';
+import { mapToTeacherDTO } from './teacher.js';
 
 /**
  * Convert a Question entity to a DTO format.
  */
 export function mapToAnswerDTO(answer: Answer): AnswerDTO {
     return {
-        author: mapToUserDTO(answer.author),
+        author: mapToTeacherDTO(answer.author),
         toQuestion: mapToQuestionDTO(answer.toQuestion),
         sequenceNumber: answer.sequenceNumber!,
         timestamp: answer.timestamp.toISOString(),

backend/src/interfaces/question.ts

@@ -1,9 +1,10 @@
 import { Question } from '../entities/questions/question.entity.js';
 import { mapToStudentDTO } from './student.js';
 import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
 
-function getLearningObjectIdentifier(question: Question): LearningObjectIdentifier {
+function getLearningObjectIdentifier(question: Question): LearningObjectIdentifierDTO {
     return {
         hruid: question.learningObjectHruid,
         language: question.learningObjectLanguage,
@@ -11,6 +12,14 @@ function getLearningObjectIdentifier(question: Question): LearningObjectIdentifi
     };
 }
 
+export function mapToLearningObjectID(loID: LearningObjectIdentifierDTO): LearningObjectIdentifier {
+    return {
+        hruid: loID.hruid,
+        language: loID.language,
+        version: loID.version ?? 1,
+    };
+}
+
 /**
  * Convert a Question entity to a DTO format.
  */

backend/src/routes/answers.ts

@@ -0,0 +1,16 @@
+import express from 'express';
+import { createAnswerHandler, deleteAnswerHandler, getAnswerHandler, getAllAnswersHandler, updateAnswerHandler } from '../controllers/answers.js';
+
+const router = express.Router({ mergeParams: true });
+
+router.get('/', getAllAnswersHandler);
+
+router.post('/', createAnswerHandler);
+
+router.get('/:seqAnswer', getAnswerHandler);
+
+router.delete('/:seqAnswer', deleteAnswerHandler);
+
+router.put('/:seqAnswer', updateAnswerHandler);
+
+export default router;

backend/src/routes/questions.ts

@@ -1,11 +1,7 @@
 import express from 'express';
-import {
-    createQuestionHandler,
-    deleteQuestionHandler,
-    getAllQuestionsHandler,
-    getQuestionAnswersHandler,
-    getQuestionHandler,
-} from '../controllers/questions.js';
+import { createQuestionHandler, deleteQuestionHandler, getAllQuestionsHandler, getQuestionHandler } from '../controllers/questions.js';
+import answerRoutes from './answers.js';
+
 const router = express.Router({ mergeParams: true });
 
 // Query language
@@ -20,6 +16,6 @@ router.delete('/:seq', deleteQuestionHandler);
 // Information about a question with id
 router.get('/:seq', getQuestionHandler);
 
-router.get('/answers/:seq', getQuestionAnswersHandler);
+router.use('/:seq/answers', answerRoutes);
 
 export default router;

backend/src/services/answers.ts

@@ -0,0 +1,70 @@
+import { getAnswerRepository } from '../data/repositories.js';
+import { Answer } from '../entities/questions/answer.entity.js';
+import { mapToAnswerDTO, mapToAnswerDTOId } from '../interfaces/answer.js';
+import { fetchTeacher } from './teachers.js';
+import { fetchQuestion } from './questions.js';
+import { QuestionId } from '@dwengo-1/common/interfaces/question';
+import { AnswerData, AnswerDTO, AnswerId } from '@dwengo-1/common/interfaces/answer';
+import { NotFoundException } from '../exceptions/not-found-exception.js';
+
+export async function getAnswersByQuestion(questionId: QuestionId, full: boolean): Promise<AnswerDTO[] | AnswerId[]> {
+    const answerRepository = getAnswerRepository();
+    const question = await fetchQuestion(questionId);
+
+    const answers: Answer[] = await answerRepository.findAllAnswersToQuestion(question);
+
+    if (full) {
+        return answers.map(mapToAnswerDTO);
+    }
+
+    return answers.map(mapToAnswerDTOId);
+}
+
+export async function createAnswer(questionId: QuestionId, answerData: AnswerData): Promise<AnswerDTO> {
+    const answerRepository = getAnswerRepository();
+    const toQuestion = await fetchQuestion(questionId);
+    const author = await fetchTeacher(answerData.author);
+    const content = answerData.content;
+
+    const answer = await answerRepository.createAnswer({
+        toQuestion,
+        author,
+        content,
+    });
+    return mapToAnswerDTO(answer);
+}
+
+async function fetchAnswer(questionId: QuestionId, sequenceNumber: number): Promise<Answer> {
+    const answerRepository = getAnswerRepository();
+    const question = await fetchQuestion(questionId);
+    const answer = await answerRepository.findAnswer(question, sequenceNumber);
+
+    if (!answer) {
+        throw new NotFoundException('Answer with questionID and sequence number not found');
+    }
+
+    return answer;
+}
+
+export async function getAnswer(questionId: QuestionId, sequenceNumber: number): Promise<AnswerDTO> {
+    const answer = await fetchAnswer(questionId, sequenceNumber);
+    return mapToAnswerDTO(answer);
+}
+
+export async function deleteAnswer(questionId: QuestionId, sequenceNumber: number): Promise<AnswerDTO> {
+    const answerRepository = getAnswerRepository();
+
+    const question = await fetchQuestion(questionId);
+    const answer = await fetchAnswer(questionId, sequenceNumber);
+
+    await answerRepository.removeAnswerByQuestionAndSequenceNumber(question, sequenceNumber);
+    return mapToAnswerDTO(answer);
+}
+
+export async function updateAnswer(questionId: QuestionId, sequenceNumber: number, answerData: AnswerData): Promise<AnswerDTO> {
+    const answerRepository = getAnswerRepository();
+    const answer = await fetchAnswer(questionId, sequenceNumber);
+
+    const newAnswer = await answerRepository.updateContent(answer, answerData.content);
+    return mapToAnswerDTO(newAnswer);
+}

backend/src/services/learning-objects/attachment-service.ts

@@ -1,10 +1,10 @@
 import { getAttachmentRepository } from '../../data/repositories.js';
 import { Attachment } from '../../entities/content/attachment.entity.js';
 
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 
 const attachmentService = {
-    async getAttachment(learningObjectId: LearningObjectIdentifier, attachmentName: string): Promise<Attachment | null> {
+    async getAttachment(learningObjectId: LearningObjectIdentifierDTO, attachmentName: string): Promise<Attachment | null> {
         const attachmentRepo = getAttachmentRepository();
 
         if (learningObjectId.version) {

backend/src/services/learning-objects/database-learning-object-provider.ts

@@ -6,7 +6,7 @@ import processingService from './processing/processing-service.js';
 import { NotFoundError } from '@mikro-orm/core';
 import learningObjectService from './learning-object-service.js';
 import { getLogger, Logger } from '../../logging/initalize.js';
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
 const logger: Logger = getLogger();
 
@@ -40,7 +40,7 @@ function convertLearningObject(learningObject: LearningObject | null): FilteredL
     };
 }
 
-async function findLearningObjectEntityById(id: LearningObjectIdentifier): Promise<LearningObject | null> {
+async function findLearningObjectEntityById(id: LearningObjectIdentifierDTO): Promise<LearningObject | null> {
     const learningObjectRepo = getLearningObjectRepository();
 
     return learningObjectRepo.findLatestByHruidAndLanguage(id.hruid, id.language);
@@ -53,7 +53,7 @@ const databaseLearningObjectProvider: LearningObjectProvider = {
     /**
      * Fetches a single learning object by its HRUID
      */
-    async getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null> {
+    async getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null> {
         const learningObject = await findLearningObjectEntityById(id);
         return convertLearningObject(learningObject);
     },
@@ -61,7 +61,7 @@ const databaseLearningObjectProvider: LearningObjectProvider = {
     /**
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string).
      */
-    async getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null> {
+    async getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null> {
         const learningObjectRepo = getLearningObjectRepository();
 
         const learningObject = await learningObjectRepo.findLatestByHruidAndLanguage(id.hruid, id.language);

backend/src/services/learning-objects/dwengo-api-learning-object-provider.ts

@@ -5,7 +5,7 @@ import { LearningObjectProvider } from './learning-object-provider.js';
 import { getLogger, Logger } from '../../logging/initalize.js';
 import {
     FilteredLearningObject,
-    LearningObjectIdentifier,
+    LearningObjectIdentifierDTO,
     LearningObjectMetadata,
     LearningObjectNode,
     LearningPathIdentifier,
@@ -67,7 +67,7 @@ async function fetchLearningObjects(learningPathId: LearningPathIdentifier, full
 
         const objects = await Promise.all(
             nodes.map(async (node) => {
-                const learningObjectId: LearningObjectIdentifier = {
+                const learningObjectId: LearningObjectIdentifierDTO = {
                     hruid: node.learningobject_hruid,
                     language: learningPathId.language,
                 };
@@ -85,7 +85,7 @@ const dwengoApiLearningObjectProvider: LearningObjectProvider = {
     /**
      * Fetches a single learning object by its HRUID
      */
-    async getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null> {
+    async getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null> {
         const metadataUrl = `${DWENGO_API_BASE}/learningObject/getMetadata`;
         const metadata = await fetchWithLogging<LearningObjectMetadata>(
             metadataUrl,
@@ -121,7 +121,7 @@ const dwengoApiLearningObjectProvider: LearningObjectProvider = {
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string). For learning objects
      * from the Dwengo API, this means passing through the HTML rendering from there.
      */
-    async getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null> {
+    async getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null> {
         const htmlUrl = `${DWENGO_API_BASE}/learningObject/getRaw`;
         const html = await fetchWithLogging<string>(htmlUrl, `Metadata for Learning Object HRUID "${id.hruid}" (language ${id.language})`, {
             params: { ...id },

backend/src/services/learning-objects/learning-object-provider.ts

@@ -1,10 +1,10 @@
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
 export interface LearningObjectProvider {
     /**
      * Fetches a single learning object by its HRUID
      */
-    getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null>;
+    getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null>;
 
     /**
      * Fetch full learning object data (metadata)
@@ -19,5 +19,5 @@ export interface LearningObjectProvider {
     /**
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string).
      */
-    getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null>;
+    getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null>;
 }

backend/src/services/learning-objects/learning-object-service.ts

@@ -2,9 +2,9 @@ import dwengoApiLearningObjectProvider from './dwengo-api-learning-object-provid
 import { LearningObjectProvider } from './learning-object-provider.js';
 import { envVars, getEnvVar } from '../../util/envVars.js';
 import databaseLearningObjectProvider from './database-learning-object-provider.js';
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
-function getProvider(id: LearningObjectIdentifier): LearningObjectProvider {
+function getProvider(id: LearningObjectIdentifierDTO): LearningObjectProvider {
     if (id.hruid.startsWith(getEnvVar(envVars.UserContentPrefix))) {
         return databaseLearningObjectProvider;
     }
@@ -18,7 +18,7 @@ const learningObjectService = {
     /**
      * Fetches a single learning object by its HRUID
      */
-    async getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null> {
+    async getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null> {
         return getProvider(id).getLearningObjectById(id);
     },
 
@@ -39,7 +39,7 @@ const learningObjectService = {
     /**
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string).
      */
-    async getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null> {
+    async getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null> {
         return getProvider(id).getLearningObjectHTML(id);
     },
 };

backend/src/services/learning-objects/processing/markdown/dwengo-marked-renderer.ts

@@ -12,7 +12,7 @@ import Image = marked.Tokens.Image;
 import Heading = marked.Tokens.Heading;
 import Link = marked.Tokens.Link;
 import RendererObject = marked.RendererObject;
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 import { Language } from '@dwengo-1/common/util/language';
 
 const prefixes = {
@@ -25,7 +25,7 @@ const prefixes = {
     blockly: '@blockly',
 };
 
-function extractLearningObjectIdFromHref(href: string): LearningObjectIdentifier {
+function extractLearningObjectIdFromHref(href: string): LearningObjectIdentifierDTO {
     const [hruid, language, version] = href.split(/\/(.+)/, 2)[1].split('/');
     return {
         hruid,

backend/src/services/learning-objects/processing/processing-service.ts

@@ -14,7 +14,7 @@ import { LearningObject } from '../../../entities/content/learning-object.entity
 import Processor from './processor.js';
 import { DwengoContentType } from './content-type.js';
 import { replaceAsync } from '../../../util/async.js';
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 import { Language } from '@dwengo-1/common/util/language';
 
 const EMBEDDED_LEARNING_OBJECT_PLACEHOLDER = /<learning-object hruid="([^"]+)" language="([^"]+)" version="([^"]+)"\/>/g;
@@ -50,7 +50,7 @@ class ProcessingService {
      */
     async render(
         learningObject: LearningObject,
-        fetchEmbeddedLearningObjects?: (loId: LearningObjectIdentifier) => Promise<LearningObject | null>
+        fetchEmbeddedLearningObjects?: (loId: LearningObjectIdentifierDTO) => Promise<LearningObject | null>
     ): Promise<string> {
         const html = this.processors.get(learningObject.contentType)!.renderLearningObject(learningObject);
         if (fetchEmbeddedLearningObjects) {

backend/src/services/questions.ts

@@ -1,22 +1,17 @@
-import { getAnswerRepository, getQuestionRepository } from '../data/repositories.js';
-import { mapToQuestionDTO, mapToQuestionDTOId } from '../interfaces/question.js';
+import { getQuestionRepository } from '../data/repositories.js';
+import { mapToLearningObjectID, mapToQuestionDTO, mapToQuestionDTOId } from '../interfaces/question.js';
 import { Question } from '../entities/questions/question.entity.js';
-import { Answer } from '../entities/questions/answer.entity.js';
-import { mapToAnswerDTO, mapToAnswerDTOId } from '../interfaces/answer.js';
 import { QuestionRepository } from '../data/questions/question-repository.js';
 import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
-import { mapToStudent } from '../interfaces/student.js';
-import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
-import { AnswerDTO, AnswerId } from '@dwengo-1/common/interfaces/answer';
+import { QuestionData, QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
+import { NotFoundException } from '../exceptions/not-found-exception.js';
+import { FALLBACK_VERSION_NUM } from '../config.js';
+import { fetchStudent } from './students.js';
 
 export async function getAllQuestions(id: LearningObjectIdentifier, full: boolean): Promise<QuestionDTO[] | QuestionId[]> {
     const questionRepository: QuestionRepository = getQuestionRepository();
     const questions = await questionRepository.findAllQuestionsAboutLearningObject(id);
 
-    if (!questions) {
-        return [];
-    }
-
     if (full) {
         return questions.map(mapToQuestionDTO);
     }
@@ -24,90 +19,57 @@ export async function getAllQuestions(id: LearningObjectIdentifier, full: boolea
     return questions.map(mapToQuestionDTOId);
 }
 
-async function fetchQuestion(questionId: QuestionId): Promise<Question | null> {
+export async function fetchQuestion(questionId: QuestionId): Promise<Question> {
     const questionRepository = getQuestionRepository();
-
-    return await questionRepository.findOne({
-        learningObjectHruid: questionId.learningObjectIdentifier.hruid,
-        learningObjectLanguage: questionId.learningObjectIdentifier.language,
-        learningObjectVersion: questionId.learningObjectIdentifier.version,
-        sequenceNumber: questionId.sequenceNumber,
-    });
-}
-
-export async function getQuestion(questionId: QuestionId): Promise<QuestionDTO | null> {
-    const question = await fetchQuestion(questionId);
+    const question = await questionRepository.findByLearningObjectAndSequenceNumber(
+        mapToLearningObjectID(questionId.learningObjectIdentifier),
+        questionId.sequenceNumber
+    );
 
     if (!question) {
-        return null;
+        throw new NotFoundException('Question with loID and sequence number not found');
     }
 
+    return question;
+}
+
+export async function getQuestion(questionId: QuestionId): Promise<QuestionDTO> {
+    const question = await fetchQuestion(questionId);
     return mapToQuestionDTO(question);
 }
 
-export async function getAnswersByQuestion(questionId: QuestionId, full: boolean): Promise<AnswerDTO[] | AnswerId[]> {
-    const answerRepository = getAnswerRepository();
-    const question = await fetchQuestion(questionId);
-
-    if (!question) {
-        return [];
-    }
-
-    const answers: Answer[] = await answerRepository.findAllAnswersToQuestion(question);
-
-    if (!answers) {
-        return [];
-    }
-
-    if (full) {
-        return answers.map(mapToAnswerDTO);
-    }
-
-    return answers.map(mapToAnswerDTOId);
-}
-
-export async function createQuestion(questionDTO: QuestionDTO): Promise<QuestionDTO | null> {
+export async function createQuestion(loId: LearningObjectIdentifier, questionData: QuestionData): Promise<QuestionDTO> {
     const questionRepository = getQuestionRepository();
+    const author = await fetchStudent(questionData.author!);
+    const content = questionData.content;
 
-    const author = mapToStudent(questionDTO.author);
-
-    const loId: LearningObjectIdentifier = {
-        ...questionDTO.learningObjectIdentifier,
-        version: questionDTO.learningObjectIdentifier.version ?? 1,
-    };
-
-    try {
-        await questionRepository.createQuestion({
+    const question = await questionRepository.createQuestion({
         loId,
         author,
-            content: questionDTO.content,
+        content,
     });
-    } catch (_) {
-        return null;
-    }
-
-    return questionDTO;
-}
-
-export async function deleteQuestion(questionId: QuestionId): Promise<QuestionDTO | null> {
-    const questionRepository = getQuestionRepository();
-
-    const question = await fetchQuestion(questionId);
-
-    if (!question) {
-        return null;
-    }
-
-    const loId: LearningObjectIdentifier = {
-        ...questionId.learningObjectIdentifier,
-        version: questionId.learningObjectIdentifier.version ?? 1,
-    };
-
-    try {
-        await questionRepository.removeQuestionByLearningObjectAndSequenceNumber(loId, questionId.sequenceNumber);
-    } catch (_) {
-        return null;
-    }
 
     return mapToQuestionDTO(question);
 }
+
+export async function deleteQuestion(questionId: QuestionId): Promise<QuestionDTO> {
+    const questionRepository = getQuestionRepository();
+    const question = await fetchQuestion(questionId); // Throws error if not found
+
+    const loId: LearningObjectIdentifier = {
+        hruid: questionId.learningObjectIdentifier.hruid,
+        language: questionId.learningObjectIdentifier.language,
+        version: questionId.learningObjectIdentifier.version || FALLBACK_VERSION_NUM,
+    };
+
+    await questionRepository.removeQuestionByLearningObjectAndSequenceNumber(loId, questionId.sequenceNumber);
+    return mapToQuestionDTO(question);
+}
+
+export async function updateQuestion(questionId: QuestionId, questionData: QuestionData): Promise<QuestionDTO> {
+    const questionRepository = getQuestionRepository();
+    const question = await fetchQuestion(questionId);
+
+    const newQuestion = await questionRepository.updateContent(question, questionData.content);
+    return mapToQuestionDTO(newQuestion);
+}

backend/src/util/links.ts

@@ -1,4 +1,4 @@
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 
 export function isValidHttpUrl(url: string): boolean {
     try {
@@ -9,7 +9,7 @@ export function isValidHttpUrl(url: string): boolean {
     }
 }
 
-export function getUrlStringForLearningObject(learningObjectId: LearningObjectIdentifier): string {
+export function getUrlStringForLearningObject(learningObjectId: LearningObjectIdentifierDTO): string {
     let url = `/learningObject/${learningObjectId.hruid}/html?language=${learningObjectId.language}`;
     if (learningObjectId.version) {
         url += `&version=${learningObjectId.version}`;
@@ -17,7 +17,7 @@ export function getUrlStringForLearningObject(learningObjectId: LearningObjectId
     return url;
 }
 
-export function getUrlStringForLearningObjectHTML(learningObjectIdentifier: LearningObjectIdentifier): string {
+export function getUrlStringForLearningObjectHTML(learningObjectIdentifier: LearningObjectIdentifierDTO): string {
     let url = `/learningObject/${learningObjectIdentifier.hruid}/html?language=${learningObjectIdentifier.language}`;
     if (learningObjectIdentifier.version) {
         url += `&version=${learningObjectIdentifier.version}`;

backend/tests/controllers/answers.test.ts

@@ -0,0 +1,87 @@
+import { Request, Response } from 'express';
+import { beforeAll, beforeEach, describe, expect, it, Mock, vi } from 'vitest';
+import { setupTestApp } from '../setup-tests';
+import { Language } from '@dwengo-1/common/util/language';
+import { getAllAnswersHandler, getAnswerHandler, updateAnswerHandler } from '../../src/controllers/answers';
+import { BadRequestException } from '../../src/exceptions/bad-request-exception';
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+
+describe('Questions controllers', () => {
+    let req: Partial<Request>;
+    let res: Partial<Response>;
+
+    let jsonMock: Mock;
+
+    beforeAll(async () => {
+        await setupTestApp();
+    });
+
+    beforeEach(() => {
+        jsonMock = vi.fn();
+        res = {
+            json: jsonMock,
+        };
+    });
+
+    it('Get answers list', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getAllAnswersHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ answers: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.answers);
+        expect(result.answers).to.have.length.greaterThan(1);
+    });
+
+    it('Get answer', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2', seqAnswer: '2' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getAnswerHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ answer: expect.anything() }));
+
+        // Const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.answer);
+    });
+
+    it('Get answer hruid does not exist', async () => {
+        req = {
+            params: { hruid: 'id_not_exist' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getAnswerHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('Get answer no hruid given', async () => {
+        req = {
+            params: {},
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getAnswerHandler(req as Request, res as Response)).rejects.toThrow(BadRequestException);
+    });
+
+    it('Update question', async () => {
+        const newContent = 'updated question';
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2', seqAnswer: '2' },
+            query: { lang: Language.English },
+            body: { content: newContent },
+        };
+
+        await updateAnswerHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ answer: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+        expect(result.answer.content).to.eq(newContent);
+    });
+});

backend/tests/controllers/questions.test.ts

@@ -0,0 +1,117 @@
+import { beforeAll, beforeEach, describe, expect, it, Mock, vi } from 'vitest';
+import { Request, Response } from 'express';
+import { setupTestApp } from '../setup-tests';
+import { getAllQuestionsHandler, getQuestionHandler, updateQuestionHandler } from '../../src/controllers/questions';
+import { Language } from '@dwengo-1/common/util/language';
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+import { BadRequestException } from '../../src/exceptions/bad-request-exception';
+
+describe('Questions controllers', () => {
+    let req: Partial<Request>;
+    let res: Partial<Response>;
+
+    let jsonMock: Mock;
+
+    beforeAll(async () => {
+        await setupTestApp();
+    });
+
+    beforeEach(() => {
+        jsonMock = vi.fn();
+        res = {
+            json: jsonMock,
+        };
+    });
+
+    it('Get question list', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getAllQuestionsHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ questions: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.questions);
+        expect(result.questions).to.have.length.greaterThan(1);
+    });
+
+    it('Get question', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '1' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getQuestionHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        // Const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+    });
+
+    it('Get question with fallback sequence number and version', async () => {
+        req = {
+            params: { hruid: 'id05' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getQuestionHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        // Const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+    });
+
+    it('Get question hruid does not exist', async () => {
+        req = {
+            params: { hruid: 'id_not_exist' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getQuestionHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('Get question no hruid given', async () => {
+        req = {
+            params: {},
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getQuestionHandler(req as Request, res as Response)).rejects.toThrow(BadRequestException);
+    });
+
+    /*
+    It('Create and delete question', async() => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2'},
+            query: { lang: Language.English },
+        };
+
+        await deleteQuestionHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        console.log(result.question);
+    });
+
+     */
+
+    it('Update question', async () => {
+        const newContent = 'updated question';
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '1' },
+            query: { lang: Language.English },
+            body: { content: newContent },
+        };
+
+        await updateQuestionHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+        expect(result.question.content).to.eq(newContent);
+    });
+});

backend/tests/services/learning-objects/learning-object-service.test.ts

@@ -7,11 +7,11 @@ import learningObjectService from '../../../src/services/learning-objects/learni
 import { envVars, getEnvVar } from '../../../src/util/envVars';
 import { LearningPath } from '../../../src/entities/content/learning-path.entity';
 import learningPathExample from '../../test-assets/learning-paths/pn-werking-example';
-import { LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 import { Language } from '@dwengo-1/common/util/language';
 
 const EXPECTED_DWENGO_LEARNING_OBJECT_TITLE = 'Werken met notebooks';
-const DWENGO_TEST_LEARNING_OBJECT_ID: LearningObjectIdentifier = {
+const DWENGO_TEST_LEARNING_OBJECT_ID: LearningObjectIdentifierDTO = {
     hruid: 'pn_werkingnotebooks',
     language: Language.Dutch,
     version: 3,

common/src/interfaces/answer.ts

@@ -1,14 +1,19 @@
-import { UserDTO } from './user';
 import { QuestionDTO, QuestionId } from './question';
+import { TeacherDTO } from './teacher';
 
 export interface AnswerDTO {
-    author: UserDTO;
+    author: TeacherDTO;
     toQuestion: QuestionDTO;
     sequenceNumber: number;
     timestamp: string;
     content: string;
 }
 
+export interface AnswerData {
+    author: string;
+    content: string;
+}
+
 export interface AnswerId {
     author: string;
     toQuestion: QuestionId;

common/src/interfaces/learning-content.ts

@@ -11,7 +11,7 @@ export interface Transition {
     };
 }
 
-export interface LearningObjectIdentifier {
+export interface LearningObjectIdentifierDTO {
     hruid: string;
     language: Language;
     version?: number;

common/src/interfaces/question.ts

@@ -1,15 +1,20 @@
-import { LearningObjectIdentifier } from './learning-content';
+import { LearningObjectIdentifierDTO } from './learning-content';
 import { StudentDTO } from './student';
 
 export interface QuestionDTO {
-    learningObjectIdentifier: LearningObjectIdentifier;
+    learningObjectIdentifier: LearningObjectIdentifierDTO;
     sequenceNumber?: number;
     author: StudentDTO;
-    timestamp?: string;
+    timestamp: string;
+    content: string;
+}
+
+export interface QuestionData {
+    author?: string;
     content: string;
 }
 
 export interface QuestionId {
-    learningObjectIdentifier: LearningObjectIdentifier;
+    learningObjectIdentifier: LearningObjectIdentifierDTO;
     sequenceNumber: number;
 }

common/src/interfaces/submission.ts

@@ -1,10 +1,10 @@
 import { GroupDTO } from './group';
-import { LearningObjectIdentifier } from './learning-content';
+import { LearningObjectIdentifierDTO } from './learning-content';
 import { StudentDTO } from './student';
 import { Language } from '../util/language';
 
 export interface SubmissionDTO {
-    learningObjectIdentifier: LearningObjectIdentifier;
+    learningObjectIdentifier: LearningObjectIdentifierDTO;
 
     submissionNumber?: number;
     submitter: StudentDTO;

frontend/src/controllers/answers.ts

@@ -0,0 +1,39 @@
+import type { AnswerData, AnswerDTO, AnswerId } from "@dwengo-1/common/interfaces/answer";
+import { BaseController } from "@/controllers/base-controller.ts";
+import type { QuestionId } from "@dwengo-1/common/interfaces/question";
+
+export interface AnswersResponse {
+    answers: AnswerDTO[] | AnswerId[];
+}
+
+export interface AnswerResponse {
+    answer: AnswerDTO;
+}
+
+export class AnswerController extends BaseController {
+    constructor(questionId: QuestionId) {
+        this.loId = questionId.learningObjectIdentifier;
+        this.sequenceNumber = questionId.sequenceNumber;
+        super(`learningObject/${loId.hruid}/:${loId.version}/questions/${this.sequenceNumber}/answers`);
+    }
+
+    async getAll(full = true): Promise<AnswersResponse> {
+        return this.get<AnswersResponse>("/", { lang: this.loId.lang, full });
+    }
+
+    async getBy(seq: number): Promise<AnswerResponse> {
+        return this.get<AnswerResponse>(`/${seq}`, { lang: this.loId.lang });
+    }
+
+    async create(answerData: AnswerData): Promise<AnswerResponse> {
+        return this.post<AnswerResponse>("/", answerData, { lang: this.loId.lang });
+    }
+
+    async remove(seq: number): Promise<AnswerResponse> {
+        return this.delete<AnswerResponse>(`/${seq}`, { lang: this.loId.lang });
+    }
+
+    async update(seq: number, answerData: AnswerData): Promise<AnswerResponse> {
+        return this.put<AnswerResponse>(`/${seq}`, answerData, { lang: this.loId.lang });
+    }
+}

frontend/src/controllers/base-controller.ts

@@ -21,20 +21,20 @@ export abstract class BaseController {
         return response.data;
     }
 
-    protected async post<T>(path: string, body: unknown): Promise<T> {
-        const response = await apiClient.post<T>(this.absolutePathFor(path), body);
+    protected async post<T>(path: string, body: unknown, queryParams?: QueryParams): Promise<T> {
+        const response = await apiClient.post<T>(this.absolutePathFor(path), body, { params: queryParams });
         BaseController.assertSuccessResponse(response);
         return response.data;
     }
 
-    protected async delete<T>(path: string): Promise<T> {
-        const response = await apiClient.delete<T>(this.absolutePathFor(path));
+    protected async delete<T>(path: string, queryParams?: QueryParams): Promise<T> {
+        const response = await apiClient.delete<T>(this.absolutePathFor(path), { params: queryParams });
         BaseController.assertSuccessResponse(response);
         return response.data;
     }
 
-    protected async put<T>(path: string, body: unknown): Promise<T> {
-        const response = await apiClient.put<T>(this.absolutePathFor(path), body);
+    protected async put<T>(path: string, body: unknown, queryParams?: QueryParams): Promise<T> {
+        const response = await apiClient.put<T>(this.absolutePathFor(path), body, { params: queryParams });
         BaseController.assertSuccessResponse(response);
         return response.data;
     }

frontend/src/controllers/questions.ts

@@ -1,5 +1,38 @@
-import type { QuestionDTO, QuestionId } from "@dwengo-1/common/interfaces/question";
+import type { QuestionData, QuestionDTO, QuestionId } from "@dwengo-1/common/interfaces/question";
+import { BaseController } from "@/controllers/base-controller.ts";
+import type { LearningObjectIdentifierDTO } from "@dwengo-1/common/interfaces/learning-content";
 
 export interface QuestionsResponse {
     questions: QuestionDTO[] | QuestionId[];
 }
+
+export interface QuestionResponse {
+    question: QuestionDTO;
+}
+
+export class QuestionController extends BaseController {
+    constructor(loId: LearningObjectIdentifierDTO) {
+        this.loId = loId;
+        super(`learningObject/${loId.hruid}/:${loId.version}/questions`);
+    }
+
+    async getAll(full = true): Promise<QuestionsResponse> {
+        return this.get<QuestionsResponse>("/", { lang: this.loId.lang, full });
+    }
+
+    async getBy(sequenceNumber: number): Promise<QuestionResponse> {
+        return this.get<QuestionResponse>(`/${sequenceNumber}`, { lang: this.loId.lang });
+    }
+
+    async create(questionData: QuestionData): Promise<QuestionResponse> {
+        return this.post<QuestionResponse>("/", questionData, { lang: this.loId.lang });
+    }
+
+    async remove(sequenceNumber: number): Promise<QuestionResponse> {
+        return this.delete<QuestionResponse>(`/${sequenceNumber}`, { lang: this.loId.lang });
+    }
+
+    async update(sequenceNumber: number, questionData: QuestionData): Promise<QuestionResponse> {
+        return this.put<QuestionResponse>(`/${sequenceNumber}`, questionData, { lang: this.loId.lang });
+    }
+}

frontend/src/queries/answers.ts

@@ -0,0 +1,51 @@
+import type { QuestionId } from "@dwengo-1/common/dist/interfaces/question.ts";
+import { type MaybeRefOrGetter, toValue } from "vue";
+import { useMutation, type UseMutationReturnType, useQuery, type UseQueryReturnType } from "@tanstack/vue-query";
+import { AnswerController, type AnswerResponse, type AnswersResponse } from "@/controllers/answers.ts";
+import type { AnswerData } from "@dwengo-1/common/dist/interfaces/answer.ts";
+
+// TODO caching
+
+export function useAnswersQuery(
+    questionId: MaybeRefOrGetter<QuestionId>,
+    full: MaybeRefOrGetter<boolean> = true,
+): UseQueryReturnType<AnswersResponse, Error> {
+    return useQuery({
+        queryFn: async () => new AnswerController(toValue(questionId)).getAll(toValue(full)),
+        enabled: () => Boolean(toValue(questionId)),
+    });
+}
+
+export function useAnswerQuery(
+    questionId: MaybeRefOrGetter<QuestionId>,
+    sequenceNumber: MaybeRefOrGetter<number>,
+): UseQueryReturnType<AnswerResponse, Error> {
+    return useQuery({
+        queryFn: async () => new AnswerController(toValue(questionId)).getBy(toValue(sequenceNumber)),
+        enabled: () => Boolean(toValue(questionId)),
+    });
+}
+
+export function useCreateAnswerMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<AnswerResponse, Error, AnswerData, unknown> {
+    return useMutation({
+        mutationFn: async (data) => new AnswerController(toValue(questionId)).create(data),
+    });
+}
+
+export function useDeleteAnswerMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<AnswerResponse, Error, number, unknown> {
+    return useMutation({
+        mutationFn: async (seq) => new AnswerController(toValue(questionId)).remove(seq),
+    });
+}
+
+export function useUpdateAnswerMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<AnswerResponse, Error, { answerData: AnswerData; seq: number }, unknown> {
+    return useMutation({
+        mutationFn: async (data, seq) => new AnswerController(toValue(questionId)).update(seq, data),
+    });
+}

frontend/src/queries/questions.ts

@@ -0,0 +1,93 @@
+import { QuestionController, type QuestionResponse, type QuestionsResponse } from "@/controllers/questions.ts";
+import type { QuestionData, QuestionId } from "@dwengo-1/common/interfaces/question";
+import type { LearningObjectIdentifierDTO } from "@dwengo-1/common/interfaces/learning-content";
+import { computed, type MaybeRefOrGetter, toValue } from "vue";
+import {
+    useMutation,
+    type UseMutationReturnType,
+    useQuery,
+    useQueryClient,
+    type UseQueryReturnType,
+} from "@tanstack/vue-query";
+
+export function questionsQueryKey(
+    loId: LearningObjectIdentifierDTO,
+    full: boolean,
+): [string, string, number, string, boolean] {
+    return ["questions", loId.hruid, loId.version, loId.language, full];
+}
+
+export function questionQueryKey(questionId: QuestionId): [string, string, number, string, number] {
+    const loId = questionId.learningObjectIdentifier;
+    return ["question", loId.hruid, loId.version, loId.language, questionId.sequenceNumber];
+}
+
+export function useQuestionsQuery(
+    loId: MaybeRefOrGetter<LearningObjectIdentifierDTO>,
+    full: MaybeRefOrGetter<boolean> = true,
+): UseQueryReturnType<QuestionsResponse, Error> {
+    return useQuery({
+        queryKey: computed(() => questionsQueryKey(toValue(loId), toValue(full))),
+        queryFn: async () => new QuestionController(toValue(loId)).getAll(toValue(full)),
+        enabled: () => Boolean(toValue(loId)),
+    });
+}
+
+export function useQuestionQuery(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseQueryReturnType<QuestionResponse, Error> {
+    const loId = toValue(questionId).learningObjectIdentifier;
+    const sequenceNumber = toValue(questionId).sequenceNumber;
+    return useQuery({
+        queryKey: computed(() => questionQueryKey(loId, sequenceNumber)),
+        queryFn: async () => new QuestionController(loId).getBy(sequenceNumber),
+        enabled: () => Boolean(toValue(questionId)),
+    });
+}
+
+export function useCreateQuestionMutation(
+    loId: MaybeRefOrGetter<LearningObjectIdentifierDTO>,
+): UseMutationReturnType<QuestionResponse, Error, QuestionData, unknown> {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationFn: async (data) => new QuestionController(toValue(loId)).create(data),
+        onSuccess: async () => {
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), true) });
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), false) });
+        },
+    });
+}
+
+export function useUpdateQuestionMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<QuestionResponse, Error, QuestionData, unknown> {
+    const queryClient = useQueryClient();
+    const loId = toValue(questionId).learningObjectIdentifier;
+    const sequenceNumber = toValue(questionId).sequenceNumber;
+
+    return useMutation({
+        mutationFn: async (data) => new QuestionController(loId).update(sequenceNumber, data),
+        onSuccess: async () => {
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), true) });
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), false) });
+            await queryClient.invalidateQueries({ queryKey: questionQueryKey(toValue(questionId)) });
+        },
+    });
+}
+
+export function useDeleteQuestionMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<QuestionResponse, Error, void, unknown> {
+    const queryClient = useQueryClient();
+    const loId = toValue(questionId).learningObjectIdentifier;
+    const sequenceNumber = toValue(questionId).sequenceNumber;
+    return useMutation({
+        mutationFn: async () => new QuestionController(loId).remove(sequenceNumber),
+        onSuccess: async () => {
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), true) });
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), false) });
+            await queryClient.invalidateQueries({ queryKey: questionQueryKey(toValue(questionId)) });
+        },
+    });
+}