feat: Generic Repository 및 UnitOfWork 패턴 구현 (#18)

- IRepository<T> 구현체: CRUD, 페이징, 조건 검색 지원
- IUnitOfWork 구현체: 트랜잭션 관리 (Begin/Commit/Rollback)
- Program.cs에 DI 등록 (AddScoped)

Closes #18

SPMS.API/Program.cs

@@ -1,6 +1,9 @@
 using Microsoft.EntityFrameworkCore;
 using SPMS.API.Middlewares;
+using SPMS.Domain.Interfaces;
 using SPMS.Infrastructure;
+using SPMS.Infrastructure.Persistence;
+using SPMS.Infrastructure.Persistence.Repositories;
 
 
 var builder = WebApplication.CreateBuilder(new WebApplicationOptions
@@ -17,6 +20,8 @@ var connectionString = builder.Configuration.GetConnectionString("DefaultConnect
 builder.Services.AddDbContext<AppDbContext>(options =>
     options.UseMySql(connectionString, ServerVersion.AutoDetect(connectionString)));
 
+builder.Services.AddScoped(typeof(IRepository<>), typeof(Repository<>));
+builder.Services.AddScoped<IUnitOfWork, UnitOfWork>();
 
 var app = builder.Build();
 

SPMS.Infrastructure/Persistence/Repositories/Repository.cs

@@ -0,0 +1,70 @@
+using System.Linq.Expressions;
+using Microsoft.EntityFrameworkCore;
+using SPMS.Domain.Entities;
+using SPMS.Domain.Interfaces;
+
+namespace SPMS.Infrastructure.Persistence.Repositories;
+
+public class Repository<T> : IRepository<T> where T : BaseEntity
+{
+    protected readonly AppDbContext _context;
+    protected readonly DbSet<T> _dbSet;
+
+    public Repository(AppDbContext context)
+    {
+        _context = context;
+        _dbSet = context.Set<T>();
+    }
+
+    public async Task<T?> GetByIdAsync(long id)
+        => await _dbSet.FindAsync(id);
+
+    public async Task<IReadOnlyList<T>> GetAllAsync()
+        => await _dbSet.ToListAsync();
+
+    public async Task<IReadOnlyList<T>> FindAsync(Expression<Func<T, bool>> predicate)
+        => await _dbSet.Where(predicate).ToListAsync();
+
+    public async Task<(IReadOnlyList<T> Items, int TotalCount)> GetPagedAsync(
+        int page, int size,
+        Expression<Func<T, bool>>? predicate = null,
+        Expression<Func<T, object>>? orderBy = null,
+        bool descending = true)
+    {
+        IQueryable<T> query = _dbSet;
+
+        if (predicate is not null)
+            query = query.Where(predicate);
+
+        var totalCount = await query.CountAsync();
+
+        if (orderBy is not null)
+            query = descending ? query.OrderByDescending(orderBy) : query.OrderBy(orderBy);
+        else
+            query = query.OrderByDescending(e => e.Id);
+
+        var items = await query
+            .Skip((page - 1) * size)
+            .Take(size)
+            .ToListAsync();
+
+        return (items, totalCount);
+    }
+
+    public async Task<int> CountAsync(Expression<Func<T, bool>>? predicate = null)
+        => predicate is null
+            ? await _dbSet.CountAsync()
+            : await _dbSet.CountAsync(predicate);
+
+    public async Task<bool> ExistsAsync(Expression<Func<T, bool>> predicate)
+        => await _dbSet.AnyAsync(predicate);
+
+    public async Task AddAsync(T entity)
+        => await _dbSet.AddAsync(entity);
+
+    public void Update(T entity)
+        => _dbSet.Update(entity);
+
+    public void Delete(T entity)
+        => _dbSet.Remove(entity);
+}

SPMS.Infrastructure/Persistence/UnitOfWork.cs

@@ -0,0 +1,50 @@
+using Microsoft.EntityFrameworkCore.Storage;
+using SPMS.Domain.Interfaces;
+
+namespace SPMS.Infrastructure.Persistence;
+
+public class UnitOfWork : IUnitOfWork
+{
+    private readonly AppDbContext _context;
+    private IDbContextTransaction? _transaction;
+
+    public UnitOfWork(AppDbContext context)
+    {
+        _context = context;
+    }
+
+    public async Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
+        => await _context.SaveChangesAsync(cancellationToken);
+
+    public async Task<IDisposable> BeginTransactionAsync(CancellationToken cancellationToken = default)
+    {
+        _transaction = await _context.Database.BeginTransactionAsync(cancellationToken);
+        return _transaction;
+    }
+
+    public async Task CommitTransactionAsync(CancellationToken cancellationToken = default)
+    {
+        if (_transaction is null)
+            throw new InvalidOperationException("Transaction has not been started.");
+
+        await _transaction.CommitAsync(cancellationToken);
+        await _transaction.DisposeAsync();
+        _transaction = null;
+    }
+
+    public async Task RollbackTransactionAsync(CancellationToken cancellationToken = default)
+    {
+        if (_transaction is null)
+            throw new InvalidOperationException("Transaction has not been started.");
+
+        await _transaction.RollbackAsync(cancellationToken);
+        await _transaction.DisposeAsync();
+        _transaction = null;
+    }
+
+    public void Dispose()
+    {
+        _transaction?.Dispose();
+        _context.Dispose();
+    }
+}