entity framework上下文6.1.3没有刷新/销毁？

在此unit testing中，我将validation内容字节列的MD5是否已正确计算，保留和提取。

但是，似乎entity framework（6.1.3）上下文未刷新/销毁，因为在原始SQL UPDATE显然生效后，但在使用新上下文获取行时未显示。

namespace UnitTests { [TestClass] public class TestDataPacketServiceDebug { [TestInitialize] public void Setup() { CommonMethods.ResetDatabase(); try { CommonMethods.ResetDataPacketDirectory(); } catch (DirectoryNotFoundException) { } } [TestCategory("DataPacketService"), TestMethod] public void TestGetLocalFilePathDebug() { // Persist a DataPacket int dataPacketId; using (var testDBContext = new TestDBContext()) { DataPacket dataPacket = new DataPacket { Content = File.ReadAllBytes(@"Resources\SampleResources.zip"), Description = "DataPacketSample consist of some random found .DLL files on disk", Name = "SampleResources", Version = "1" }; testDBContext.DataPackets.Add(dataPacket); testDBContext.SaveChanges(); dataPacketId = dataPacket.DataPacketId; } // Verify file path extraction using (var testDBContext = new TestDBContext()) { DataPacket dataPacket = DataPacketService.GetByNameAndVersion("SampleResources", "1", testDBContext); string extractedFilePath = DataPacketService.GetLocalFilePath(testDBContext, dataPacket, "EntityFramework.dll"); string validDestinationPath = String.Format(@"{0}\DataPackets\{1}_v{2}\EntityFramework.dll", AppDomain.CurrentDomain.BaseDirectory, dataPacket.Name, dataPacket.Version); Assert.AreEqual(validDestinationPath, extractedFilePath); if (File.Exists(extractedFilePath) == false) { Assert.Fail("SampleResources was not extracted correctly"); } } // When setting a breakpoint here and take a look with external SQL Browser // (eg Microsoft SQL Server Management Studio), following is in order: // Note! Not all columns are shown // ----------------------------------------------------------------------------------------------- // DataPacketId | Name | RowVersion | Content | MD5 | Version // 1 | SampleResources | NULL | 0x504B03... | 2zSV8IChaiyf0UfnezDHKg== | 1 // Manually modify MD5 field in database for MD5 verification using (var testDBContext = new TestDBContext()) { string sqlUpdate = String.Format("UPDATE dbo.DataPackets SET MD5 = 'another_MD5' WHERE DataPacketId = {0}", dataPacketId); testDBContext.Database.ExecuteSqlCommand(sqlUpdate); } // When setting a breakpoint here we can clearly see that the row has been changed: // Note! Not all columns are shown // ---------------------------------------------------------------------------------- // DataPacketId | Name | RowVersion | Content | MD5 | Version // 1 | SampleResources | NULL | 0x504B03... | another_MD5 | 1 // Verify MD5 using (var testDBContext = new TestDBContext()) { // Fetch dataPacket with modified MD5 DataPacket dataPacket = DataPacketService.GetByNameAndVersion("SampleResources", "1", testDBContext); // Verify that the raw SQL command has been successful: Assert.AreEqual("another_MD5", dataPacket.MD5); // BANG!!!!!!!!!!!!!! // Result Message: Assert.AreEqual failed. Expected:.Actual:. } } } } 

实体：

 public class DataPacket { /// 
 /// Identifier /// 
 public int DataPacketId { get; set; } /// 
 /// Concurrency Token /// 
 public byte[] RowVersion { get; set; } /// 
 /// Name /// 
 public string Name { get; set; } /// 
 /// Description of data packet /// 
 public string Description { get; set; } /// 
 /// Version of data packet /// 
 public string Version { get; set; } /// 
 /// MD5 of the data packet (ie MD5 of Content byte array) /// 
 public string MD5 { get; private set; } private byte[] content; /// 
 /// Byte content of the data packet (ie /// 
 public byte[] Content { get { return content; } set { content = value; UpdateMD5(); } } /// 
 /// TestCase navigation DataPacket  TestCases /// 
 public ICollection TestCases { get; set; } // DataPacket  TestCases /// 
 /// Update MD5 checksum depending on content /// 
 private void UpdateMD5() { if (content != null) { this.MD5 = GetMD5ForBytes(content); } } /// 
 /// Get MD5 checksum for content byte array /// 
 /// Content byte array /// MD5 checksum public static String GetMD5ForBytes(byte[] content) { if (content != null) { System.Security.Cryptography.MD5 md5Object = System.Security.Cryptography.MD5.Create(); return System.BitConverter.ToString(md5Object.ComputeHash(content)).Replace("-", ""); } return null; } } 

GetByNameAndVersion

 public static DataPacket GetByNameAndVersion(string name, string version, TestDBContext testDBContext) { IQueryable query = testDBContext.Set(); query = query.Where(t => t.Name == name).Where(t => t.Version == version); return query.Single(); } 

注意！ 我正在使用localDB数据库。

Answer 1

它不是EF上下文问题（它按预期工作），但是DataPacket类中的测试/逻辑不正确。

您有两个相关属性，都映射到数据库表列：

 /// 
 /// MD5 of the data packet (ie MD5 of Content byte array) /// 
 public string MD5 { get; private set; } private byte[] content; /// 
 /// Byte content of the data packet (ie /// 
 public byte[] Content { get { return content; } set { content = value; UpdateMD5(); } } 

客户端C＃代码只能设置Content ，而Content又会更新MD5 – 很好。 但是当EF从数据库加载实体时会发生什么？ 实际上，它使用相同的属性设置器（ private不是问题，因为EF使用reflection/代码生成，因此它可以在外部调用任何类型的setter）。

现在一切都取决于调用setter的顺序 。 在您的情况下，首先调用MD5 ，然后调用Content 。 由于您的SQL命令更新了MD5列，但保留了Content不变，因此第一个setter将从数据库中设置MD5值，第二个setter将从Content更新它。 这当然导致断言报告失败。

您可以决定是否通过SQL更新数据库中的MD5列是有效操作（基本上使MD5和Content不同步）。 在undefined中调用属性setter的顺序 – 当前如果你在Content属性之后移动MD5属性声明，测试将通过，但这是你不能依赖的东西。