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CloudBuilder.Core/DatabaseAccessor/UnitOfWorkAttribute.cs

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+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.EntityFrameworkCore;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Transactions;
+
+namespace CloudBuilder.Core.DatabaseAccessor
+{
+    /*
+        事务范围不匹配：TransactionScope 管理的是分布式事务，但对于单个数据库连接，通常不需要分布式事务。
+        OnActionExecutionAsync 是 ASP.NET Core 中异步的 Action 过滤器执行方法。
+        // OnActionExecuting: Action 执行前
+        [开始事务]
+        ↓
+        [Action 方法执行]
+        ↓
+        // OnActionExecuted: Action 执行后（无论是否异常）
+        [检查异常]
+        [提交或回滚事务]
+     */
+    [AttributeUsage(AttributeTargets.Method)]
+    public class UnitOfWorkAttribute : ActionFilterAttribute
+    {
+        private TransactionScope _transactionScope;
+
+        public override void OnActionExecuting(ActionExecutingContext context)
+        {
+            _transactionScope = new TransactionScope(TransactionScopeOption.RequiresNew,
+                new TransactionOptions
+                {
+                    IsolationLevel = IsolationLevel.ReadCommitted,
+                    Timeout = TransactionManager.MaximumTimeout
+                });
+
+            base.OnActionExecuting(context);
+        }
+
+        public override void OnActionExecuted(ActionExecutedContext context)
+        {
+            if (_transactionScope != null)
+            {
+                if (context.Exception == null)
+                {
+                    //必须要有 SaveChanges() 调用，否则数据只会停留在内存中，不会真正保存到数据库。
+                    _transactionScope.Complete();
+                }
+                _transactionScope.Dispose();
+            }
+
+            base.OnActionExecuted(context);
+        }
+    }
+}