在 RPi 3（控制台应用程序）上运行的 Windows IoT 上的 Entity Framework Core

Question

我成功地将 .NET Core 控制台应用程序部署到在 Raspberry Pi 3 上运行的 Windows IoT。

应用程序从 Web 服务中提取数据并将它们存储在数据库中。我为此使用了 Entity Framework Core。

当我通过远程 powershell 启动已部署的控制台应用程序 (.exe) 时，除了访问在 Azure 上运行的数据库之外，一切正常。当应用程序尝试从数据库中读取时，它会抛出以下异常：

System.TypeInitializationException: The type initializer for 'System.Data.SqlClient.TdsParser' threw an exception. ---> System.TypeInitializationException: The type initializer for 'System.Data.SqlClient.SNILoadHandle' threw an exception. ---> System.DllNotFoundException: Unable to load DLL 'sni.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
   at System.Data.SqlClient.SNINativeMethodWrapper.SNIInitialize(IntPtr pmo)
   at System.Data.SqlClient.SNILoadHandle..ctor()
   at System.Data.SqlClient.SNILoadHandle..cctor()
   --- End of inner exception stack trace ---
   at System.Data.SqlClient.TdsParser..cctor()
   --- End of inner exception stack trace ---
   at System.Data.SqlClient.TdsParser..ctor(Boolean MARS, Boolean fAsynchronous)
   at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, TimeoutTimer timeout)
   at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, Boolean redirectedUserInstance)
   at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, Boolean applyTransientFaultHandling)
   at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open()
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable.Enumerator.BufferlessMoveNext(Boolean buffer)
   at Microsoft.EntityFrameworkCore.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](Func`2 operation, Func`2 verifySucceeded, TState state)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, Func`2 operation, TState state)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable.Enumerator.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.QueryMethodProvider.<_ShapedQuery>d__3`1.MoveNext()
   at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable`1 source, Boolean& found)
   at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
   at lambda_method(Closure , QueryContext )
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass20_0`1.<CompileQueryCore>b__0(QueryContext qc)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
   at System.Linq.Queryable.First[TSource](IQueryable`1 source)

应用程序文件夹中没有“sni.dll”。

使用“win8-arm”运行时部署应用程序。

• netcoreapp2.0
• .NET Core 2.0 SDK（运行时和工具）

有什么想法吗？

更新：

复制 System.Data.SqlClient.dll (unix lib) 并覆盖应用程序文件夹中现有的解决了该问题。请参阅下面的答案。

Answer 1

没有适用于 ARM 的本机 sni.dll 库。 （见dotnet/corefx#9064）

我希望我能告诉你如何使用 System.Data.SqlClient（Linux 上使用的那个）的完全托管实现，但不幸的是它使用了 UWP 上不可用的 System.Threading.Thread...

[更新1]
等等，你没有使用 UWP。 :) 尝试让应用在运行时使用 %USERPROFILE%.nuget\packages\system.data.sqlclient\4.3.0\runtimes\unix\lib\netstandard1.3\System.Data.SqlClient.dll。

[更新2]
在 System.Data.SqlClient 版本 4.4.0 中，默认是完全托管的。