chore: 提交当前变更

src/Infrastructure/TakeoutSaaS.Infrastructure/Common/Persistence/TenantAwareDbContext.cs

@@ -0,0 +1,89 @@
+using System.Reflection;
+using Microsoft.EntityFrameworkCore;
+using TakeoutSaaS.Shared.Abstractions.Entities;
+using TakeoutSaaS.Shared.Abstractions.Tenancy;
+
+namespace TakeoutSaaS.Infrastructure.Common.Persistence;
+
+/// <summary>
+/// 多租户感知 DbContext：自动应用租户过滤并填充租户字段。
+/// </summary>
+public abstract class TenantAwareDbContext : DbContext
+{
+    private readonly ITenantProvider _tenantProvider;
+
+    protected TenantAwareDbContext(DbContextOptions options, ITenantProvider tenantProvider) : base(options)
+    {
+        _tenantProvider = tenantProvider;
+    }
+
+    /// <summary>
+    /// 当前请求租户 ID。
+    /// </summary>
+    protected Guid CurrentTenantId => _tenantProvider.GetCurrentTenantId();
+
+    /// <summary>
+    /// 应用租户过滤器至所有实现 <see cref="IMultiTenantEntity"/> 的实体。
+    /// </summary>
+    protected void ApplyTenantQueryFilters(ModelBuilder modelBuilder)
+    {
+        foreach (var entityType in modelBuilder.Model.GetEntityTypes())
+        {
+            if (!typeof(IMultiTenantEntity).IsAssignableFrom(entityType.ClrType))
+            {
+                continue;
+            }
+
+            var methodInfo = typeof(TenantAwareDbContext)
+                .GetMethod(nameof(SetTenantFilter), BindingFlags.Instance | BindingFlags.NonPublic)!
+                .MakeGenericMethod(entityType.ClrType);
+
+            methodInfo.Invoke(this, new object[] { modelBuilder });
+        }
+    }
+
+    private void SetTenantFilter<TEntity>(ModelBuilder modelBuilder)
+        where TEntity : class, IMultiTenantEntity
+    {
+        modelBuilder.Entity<TEntity>().HasQueryFilter(entity => entity.TenantId == CurrentTenantId);
+    }
+
+    public override int SaveChanges()
+    {
+        ApplyTenantMetadata();
+        return base.SaveChanges();
+    }
+
+    public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
+    {
+        ApplyTenantMetadata();
+        return base.SaveChangesAsync(cancellationToken);
+    }
+
+    private void ApplyTenantMetadata()
+    {
+        var tenantId = CurrentTenantId;
+
+        foreach (var entry in ChangeTracker.Entries<IMultiTenantEntity>())
+        {
+            if (entry.State == EntityState.Added && entry.Entity.TenantId == Guid.Empty && tenantId != Guid.Empty)
+            {
+                entry.Entity.TenantId = tenantId;
+            }
+        }
+
+        var utcNow = DateTime.UtcNow;
+        foreach (var entry in ChangeTracker.Entries<IAuditableEntity>())
+        {
+            if (entry.State == EntityState.Added)
+            {
+                entry.Entity.CreatedAt = utcNow;
+                entry.Entity.UpdatedAt = null;
+            }
+            else if (entry.State == EntityState.Modified)
+            {
+                entry.Entity.UpdatedAt = utcNow;
+            }
+        }
+    }
+}