当我尝试插入相同的数据时,我收到 NullReferenceException 异常。
我在 Stackoverflow、asp.net 论坛和 mysql 社区论坛上阅读了大量帖子。 我找不到这个问题的任何真正的解决方案。关于这个问题有很多答案。然而,有人解决了我的问题(也是其他人的问题)。我发现了一些关于此类问题的错误报告。然而,每个报告都应该在 .Net Connector 6.8.3 中解决。 我认为我在 EF 与 Mysql 中缺少非常简单的步骤,但我找不到我的错误是什么......
示例代码:
using (prodEntities myEntity = new prodEntities ())
{
userloginlog log = new userloginlog();
log.UserRef = pUserID;
log.Success = pSuccess;
log.IpNo = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"].ToString();
log.BrowserInfo = browserInfo;
log.LoginTime = GeneralHelperC.getCompanyDateTime();
myEntity.userloginlog.Add(log);
myEntity.SaveChanges();
}
表:
CREATE TABLE `userloginlog` (
`RID` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`UserRef` bigint(20) unsigned NOT NULL,
`LoginTime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`IpNo` varchar(15) DEFAULT NULL,
`Success` tinyint(4) NOT NULL,
`BrowserInfo` varchar(1000) DEFAULT NULL,
PRIMARY KEY (`RID`),
KEY `userLoginLog_Staff_Key` (`UserRef`),
CONSTRAINT `UserLoginLog_User_Key` FOREIGN KEY (`UserRef`) REFERENCES `users` (`RID`)
) ENGINE=InnoDB AUTO_INCREMENT=16903 DEFAULT CHARSET=utf8;
异常(exception):
at MySql.Data.Entity.ListFragment.WriteSql(StringBuilder sql)
at MySql.Data.Entity.SelectStatement.WriteSql(StringBuilder sql)
at MySql.Data.Entity.InsertStatement.WriteSql(StringBuilder sql)
at MySql.Data.Entity.SqlFragment.ToString()
at MySql.Data.Entity.InsertGenerator.GenerateSQL(DbCommandTree tree)
at MySql.Data.MySqlClient.MySqlProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree)
at System.Data.Entity.Core.Common.DbProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree, DbInterceptionContext interceptionContext)
at System.Data.Entity.Core.Common.DbProviderServices.CreateCommandDefinition(DbCommandTree commandTree, DbInterceptionContext interceptionContext)
at System.Data.Entity.Core.Common.DbProviderServices.CreateCommand(DbCommandTree commandTree, DbInterceptionContext interceptionContext)
at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.CreateCommand(DbModificationCommandTree commandTree)
at System.Data.Entity.Core.Mapping.Update.Internal.DynamicUpdateCommand.CreateCommand(Dictionary`2 identifierValues)
at System.Data.Entity.Core.Mapping.Update.Internal.DynamicUpdateCommand.Execute(Dictionary`2 identifierValues, List`1 generatedValues)
at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.<Update>b__2(UpdateTranslator ut)
at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update[T](T noChangesResult, Func`2 updateFunction)
at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update()
at System.Data.Entity.Core.Objects.ObjectContext.<SaveChangesToStore>b__d()
at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesToStore(SaveOptions options, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction)
at System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClassb.<SaveChangesInternal>b__8()
at System.Data.Entity.Infrastructure.DefaultExecutionStrategy.Execute[TResult](Func`1 operation)
at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesInternal(SaveOptions options, Boolean executeInExistingTransaction)
at System.Data.Entity.Core.Objects.ObjectContext.SaveChanges(SaveOptions options)
at System.Data.Entity.Internal.InternalContext.SaveChanges()
at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
at System.Data.Entity.DbContext.SaveChanges()
安装在我的电脑上:
- Mysql 服务器 5.6CE
- MySQL 连接器 NET 6.8.3
- Visual Studio 2013
项目中引用的 DLL(每个人都使用 nuget 安装):
- MySql.Data.dll (6.8.3)
- MySql.Data.Entity.dll (6.7.5)
- MySql.Data.Entities.dll (6.8.3.0)
- MySql.Web.dll (6.8.3)
- EntityFramework.dll (6.1.1)
项目是在.Net Framework 4.0下运行的Asp.Net Webform
非常感谢
最佳答案
如果您使用的是 Entity Framework 6,则要使用的正确 MySql 数据实体是 MySql.Data.Entity.EF6
。我有一个 Webforms 项目,我正在使用 VS 2013 和 MySql。 Mysql 引用如下所示:
您不需要 MySql.Data.Entity.dll (6.7.5)
或 MySql.Data.Entities.dll (6.8.3.0)
。
对于您的 Web.config:
<entityFramework>
<providers>
<provider invariantName="MySql.Data.MySqlClient"
type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6" />
</providers>
</entityFramework>
<system.data>
<DbProviderFactories>
<remove invariant="MySql.Data.MySqlClient"></remove>
<add name="MySQL Data Provider"
invariant="MySql.Data.MySqlClient"
description=".Net Framework Data Provider for MySQL"
type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.8.3.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
</DbProviderFactories>
</system.data>
关于c# - 带有 Mysql 和 NullReferenceException 的 Entity Framework 6,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24545216/