Changed domains, configured links between VisaApplication and Applicant,created generic repository and repositories for domains

SchengenVisaApi/Infrastructure/Database/Generic/GenericRepository.cs

@@ -0,0 +1,38 @@
+using Domains;
+using Infrastructure.Database.GeneralExceptions;
+using Microsoft.EntityFrameworkCore;
+
+namespace Infrastructure.Database.Generic
+{
+    public abstract class GenericRepository<T>(IGenericWriter writer, IUnitOfWork unitOfWork) : IGenericRepository<T>
+        where T : class, IEntity
+    {
+        public async Task<List<T>> GetAllAsync(CancellationToken cancellationToken)
+            => await LoadDomain().ToListAsync(cancellationToken);
+
+        public async Task<T> GetOneAsync(Guid id, CancellationToken cancellationToken)
+        {
+            var result = await LoadDomain().SingleOrDefaultAsync(a => a.Id == id, cancellationToken);
+            return result ?? throw new EntityNotFoundException<T>(id);
+        }
+
+        public async Task AddAsync(T entity, CancellationToken cancellationToken)
+            => await writer.AddAsync(entity, cancellationToken);
+
+        public async Task UpdateAsync(T entity, CancellationToken cancellationToken)
+        {
+            await GetOneAsync(entity.Id, cancellationToken);
+            writer.Update(entity);
+        }
+
+        public void Remove(T entity)
+        {
+            writer.Remove(entity);
+        }
+
+        public async Task SaveAsync(CancellationToken cancellationToken)
+            => await unitOfWork.SaveAsync(cancellationToken);
+
+        protected abstract IQueryable<T> LoadDomain();
+    }
+}