MySQL的实体框架 - 我究竟做错了什么？ [英] MySQL with Entity Framework - what am I doing wrong?

问题描述

我是完全新的实体框架，甚至ADO.NET一般（通常不会做数据库的大量工作）。

1. 我下载并安装的MySQL Connector / NET 6.3.5 。
2. 我在Visual Studio 2010中创建一个新的C＃项目。
3. 我添加了一个新的ADO.NET实体数据模型到我的项目，并选择从数据库生成。
4. 在我加入到我的本地MySQL服务器瓦特/服务器名localhost的+我的用户名和密码，一个新的连接。
5. 在我检查所有的表从我的MySQL数据库生成对象的。
6. 我写了下面code：

（的东西只是一个假表我有一些任意字段扔在一起。）

  TestDataEntities实体=新TestDataEntities（）;

VAR东西= entities.things.Execute（MergeOption.AppendOnly）; // 例外
 

上面扔了的NullReferenceException ，我真的无言以对，为什么这可能是。当我测试连接，它说，它成功了。我已经肯定设置了正确的用户名和密码的连接。我甚至不知道还有什么调查。

对于那些你究竟是谁知道这个东西，这里的例外，我得到了（虽然我未受过训练的眼中，这实际上并不像它会是所有有用）：

   在MySql.Data.MySqlClient.MySqlClientFactory.get_MySqlDbProviderServicesInstance（）
   在MySql.Data.MySqlClient.MySqlClientFactory.System.IServiceProvider.GetService（类型的serviceType）
   在System.Data.Common.DbProviderServices.GetProviderServices（DbProviderFactory厂）
   在System.Data.Metadata.Edm.StoreItemCollection.Loader.InitializeProviderManifest（Action`3 addError）
   在System.Data.Metadata.Edm.StoreItemCollection.Loader.OnProviderManifestTokenNotification（字符串标记，Action`3 addError）
   在System.Data.EntityModel.SchemaObjectModel.Schema.HandleProviderManifestTokenAttribute（XmlReader的读者）
   在System.Data.EntityModel.SchemaObjectModel.Schema.HandleAttribute（XmlReader的读者）
   在System.Data.EntityModel.SchemaObjectModel.SchemaElement.ParseAttribute（XmlReader的读者）
   在System.Data.EntityModel.SchemaObjectModel.SchemaElement.Parse（XmlReader的读者）
   在System.Data.EntityModel.SchemaObjectModel.Schema.HandleTopLevelSchemaElement（XmlReader的读者）
   在System.Data.EntityModel.SchemaObjectModel.Schema.InternalParse（XmlReader的sourceReader，串sourceLocation）
   在System.Data.EntityModel.SchemaObjectModel.Schema.Parse（XmlReader的sourceReader，串sourceLocation）
   在System.Data.EntityModel.SchemaObjectModel.SchemaManager.ParseAndValidate（IEnumerable`1 xmlReaders，IEnumerable`1 sourceFilePaths，SchemaDataModelOption数据模型，AttributeValueNotification providerNotification，AttributeValueNotification providerManifestTokenNotification，ProviderManifestNeeded providerManifestNeeded，IList`1＆schemaCollection）
   在System.Data.Metadata.Edm.StoreItemCollection.Loader.LoadItems（IEnumerable`1 xmlReaders，IEnumerable`1 sourceFilePaths）
   在System.Data.Metadata.Edm.StoreItemCollection.Init（IEnumerable`1 xmlReaders，IEnumerable`1文件路径，布尔throwOnError，DbProviderManifest和providerManifest，DbProviderFactory和providerFactory，Memoizer`2＆cachedCTypeFunction）
   在System.Data.Metadata.Edm.StoreItemCollection..ctor（IEnumerable`1 xmlReaders，IEnumerable`1文件路径）
   在System.Data.Metadata.Edm.MetadataCache.StoreMetadataEntry.LoadStoreCollection（EdmItemCollection edmItemCollection，MetadataArtifactLoader装载机）
   在System.Data.Metadata.Edm.MetadataCache.StoreItemCollectionLoader.LoadItemCollection(StoreMetadataEntry条目）
   在System.Data.Metadata.Edm.MetadataCache.LoadItemCollection [T]（IItemCollectionLoader`1 itemCollectionLoader，T项）
   在System.Data.Metadata.Edm.MetadataCache.GetOrCreateStoreAndMappingItemCollections（字符串cacheKey，MetadataArtifactLoader装载机，EdmItemCollection edmItemCollection，对象和entryToken）
   在System.Data.EntityClient.EntityConnection.LoadStoreItemCollections（MetadataWorkspace工作区，的DbConnection storeConnection，DbProviderFactory厂，DbConnectionOptions connectionOptions，EdmItemCollection edmItemCollection，MetadataArtifactLoader artifactLoader）
   在System.Data.EntityClient.EntityConnection.GetMetadataWorkspace（布尔initializeAllCollections）
   在System.Data.EntityClient.EntityConnection.InitializeMetadata（的DbConnection newConnection，的DbConnection originalConnection，布尔closeOriginalConnectionOnFailure）
   在System.Data.EntityClient.EntityConnection.Open（）
   在System.Data.Objects.ObjectContext.EnsureConnection（）
   在System.Data.Objects.ObjectQuery`1.GetResults（Nullable`1 forMergeOption）
   在System.Data.Objects.ObjectQuery`1.Execute（MergeOption mergeOption）
   在EntityFrameworkTest.Form1..ctor（）在D：\开发\ EntityFrameworkTest \ Form1.cs中：第23行
   在EntityFrameworkTest.Program.Main（）在D：\开发\ EntityFrameworkTest \的Program.cs：行18
   在System.AppDomain._nExecuteAssembly（议会会议，字串[] args）
   在System.AppDomain.ExecuteAssembly（字符串assemblyFile，证据assemblySecurity，字串[] args）
   在Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly（）
   在System.Threading.ThreadHelper.ThreadStart_Context（对象状态）
   在System.Threading.ExecutionContext.Run（ExecutionContext中的ExecutionContext，ContextCallback回调，对象的状态）
   在System.Threading.ThreadHelper.ThreadStart（）

解决方案

我通过增加提及MySql.Data.Entity.dll（和MySql.Web.dll）得到了过去的这个错误

I am completely new to Entity Framework and even ADO.NET in general (don't typically do much work with databases).

1. I downloaded and installed MySQL Connector/NET 6.3.5.
2. I created a new C# project in Visual Studio 2010.
3. I added a new ADO.NET Entity Data Model to my project and chose "Generate from database."
4. I added a new connection to my local MySQL server w/ server name "localhost" + my user name and password.
5. I checked all of the tables from my MySQL database to generate objects for.
6. I wrote the following code:

(things is just a bogus table I threw together with some arbitrary fields.)

TestDataEntities entities = new TestDataEntities();

var things = entities.things.Execute(MergeOption.AppendOnly); // exception

The above threw a NullReferenceException and I'm really clueless as to why that could be. When I test the connection, it says it succeeded. I have definitely set up the connection with the correct user name and password. I don't even know what else to investigate.

For those of you who actually know about this stuff, here's the exception I got (though, to my untrained eyes, this doesn't actually look like it would be all that helpful):

   at MySql.Data.MySqlClient.MySqlClientFactory.get_MySqlDbProviderServicesInstance()
   at MySql.Data.MySqlClient.MySqlClientFactory.System.IServiceProvider.GetService(Type serviceType)
   at System.Data.Common.DbProviderServices.GetProviderServices(DbProviderFactory factory)
   at System.Data.Metadata.Edm.StoreItemCollection.Loader.InitializeProviderManifest(Action`3 addError)
   at System.Data.Metadata.Edm.StoreItemCollection.Loader.OnProviderManifestTokenNotification(String token, Action`3 addError)
   at System.Data.EntityModel.SchemaObjectModel.Schema.HandleProviderManifestTokenAttribute(XmlReader reader)
   at System.Data.EntityModel.SchemaObjectModel.Schema.HandleAttribute(XmlReader reader)
   at System.Data.EntityModel.SchemaObjectModel.SchemaElement.ParseAttribute(XmlReader reader)
   at System.Data.EntityModel.SchemaObjectModel.SchemaElement.Parse(XmlReader reader)
   at System.Data.EntityModel.SchemaObjectModel.Schema.HandleTopLevelSchemaElement(XmlReader reader)
   at System.Data.EntityModel.SchemaObjectModel.Schema.InternalParse(XmlReader sourceReader, String sourceLocation)
   at System.Data.EntityModel.SchemaObjectModel.Schema.Parse(XmlReader sourceReader, String sourceLocation)
   at System.Data.EntityModel.SchemaObjectModel.SchemaManager.ParseAndValidate(IEnumerable`1 xmlReaders, IEnumerable`1 sourceFilePaths, SchemaDataModelOption dataModel, AttributeValueNotification providerNotification, AttributeValueNotification providerManifestTokenNotification, ProviderManifestNeeded providerManifestNeeded, IList`1& schemaCollection)
   at System.Data.Metadata.Edm.StoreItemCollection.Loader.LoadItems(IEnumerable`1 xmlReaders, IEnumerable`1 sourceFilePaths)
   at System.Data.Metadata.Edm.StoreItemCollection.Init(IEnumerable`1 xmlReaders, IEnumerable`1 filePaths, Boolean throwOnError, DbProviderManifest& providerManifest, DbProviderFactory& providerFactory, Memoizer`2& cachedCTypeFunction)
   at System.Data.Metadata.Edm.StoreItemCollection..ctor(IEnumerable`1 xmlReaders, IEnumerable`1 filePaths)
   at System.Data.Metadata.Edm.MetadataCache.StoreMetadataEntry.LoadStoreCollection(EdmItemCollection edmItemCollection, MetadataArtifactLoader loader)
   at System.Data.Metadata.Edm.MetadataCache.StoreItemCollectionLoader.LoadItemCollection(StoreMetadataEntry entry)
   at System.Data.Metadata.Edm.MetadataCache.LoadItemCollection[T](IItemCollectionLoader`1 itemCollectionLoader, T entry)
   at System.Data.Metadata.Edm.MetadataCache.GetOrCreateStoreAndMappingItemCollections(String cacheKey, MetadataArtifactLoader loader, EdmItemCollection edmItemCollection, Object& entryToken)
   at System.Data.EntityClient.EntityConnection.LoadStoreItemCollections(MetadataWorkspace workspace, DbConnection storeConnection, DbProviderFactory factory, DbConnectionOptions connectionOptions, EdmItemCollection edmItemCollection, MetadataArtifactLoader artifactLoader)
   at System.Data.EntityClient.EntityConnection.GetMetadataWorkspace(Boolean initializeAllCollections)
   at System.Data.EntityClient.EntityConnection.InitializeMetadata(DbConnection newConnection, DbConnection originalConnection, Boolean closeOriginalConnectionOnFailure)
   at System.Data.EntityClient.EntityConnection.Open()
   at System.Data.Objects.ObjectContext.EnsureConnection()
   at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
   at System.Data.Objects.ObjectQuery`1.Execute(MergeOption mergeOption)
   at EntityFrameworkTest.Form1..ctor() in D:\Development\EntityFrameworkTest\Form1.cs:line 23
   at EntityFrameworkTest.Program.Main() in D:\Development\EntityFrameworkTest\Program.cs:line 18
   at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
   at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

解决方案

I got past this error by adding a reference to MySql.Data.Entity.dll (and MySql.Web.dll)

这篇关于MySQL的实体框架 - 我究竟做错了什么？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！