add basic versions of retrieving answers by question or completion

SurveyBackend/SurveyBackend.API/Controllers/AnswerController.cs

@@ -0,0 +1,37 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using SurveyBackend.Mappers;
+using SurveyLib.Core.Services;
+
+namespace SurveyBackend.Controllers;
+
+[ApiController]
+public class AnswerController : ControllerBase
+{
+    private readonly IAnswerService _answerService;
+
+    public AnswerController(IAnswerService answerService)
+    {
+        _answerService = answerService;
+    }
+
+    [Authorize]
+    [HttpGet]
+    [Route("api/questions/{id:int}/answers")]
+    public async Task<IActionResult> GetAnswersByQuestionId(int id)
+    {
+        var models = await _answerService.GetAnswersByQuestionIdAsync(id);
+        var result = models.Select(AnswerMapper.ModelToOutputDto);
+        return Ok(result);
+    }
+
+    [Authorize]
+    [HttpGet]
+    [Route("api/completions/{id:int}/answers")]
+    public async Task<IActionResult> GetAnswersByCompletionId(int id)
+    {
+        var models = await _answerService.GetAnswersByCompletionIdAsync(id);
+        var result = models.Select(AnswerMapper.ModelToOutputDto);
+        return Ok(result);
+    }
+}