Added new controller for getting observation by patient id and hl7 id

Controllers/PatientsController.cs

@@ -1,5 +1,6 @@
 using AutoMapper;
 using Microsoft.AspNetCore.Mvc;
+using SimpleLIS.DTO;
 using SimpleLIS.Models;
 using SimpleLIS.Services;
 
@@ -41,6 +42,16 @@ public class PatientsController : ControllerBase
         return Ok(patientDto);
     }
 
+    [HttpGet("{id}/observations")]
+    public async Task<IActionResult> GetPatientObservationById(string id){
+        List<Observation> observations;
+        if(int.TryParse(id, out int patientId))
+            observations = await _patientService.GetPatientObservationById(patientId);
+        else
+            observations = await _patientService.GetPatientObservationByHL7PatientId(id);
+        return Ok(_mapper.Map<List<ObservationDTO>>(observations));
+    }
+
     [HttpGet]
     public async Task<IActionResult> ListPatients()
     {

Services/PatientService.cs

@@ -26,6 +26,16 @@ public class PatientService
             .FirstOrDefaultAsync(p => p.PatientId == id);
     }
 
+    public async Task<List<Observation>> GetPatientObservationById(int id){
+        return await _context.Observations.Include(observation=>observation.Message)
+        .Where(observation=>observation.Message.PatientId==id).ToListAsync();
+    }
+
+    public async Task<List<Observation>> GetPatientObservationByHL7PatientId(string id){
+        return await _context.Observations.Include(observation => observation.Message)
+        .Where(observation => observation.Message.Patient.HL7PatientId == id).ToListAsync();
+    }
+
     public async Task<IEnumerable<Patient>> ListPatientsAsync()
     {
         return await _context.Patients.ToListAsync();