Question

我有一个将要执行基于实体框架的查询的类。这个类是一个通用类，是DbContext独立类（我的意思是没有ssdl或semiliar文件）。在这个类中，我也将执行原始的SQL查询。为此，我添加了一个方法：

 Return _dbContext.Database.SqlQuery(Of String)(query).FirstOrDefault()

执行标量。但是在这个阶段有一个错误：

Additional information: Argument 'xmlReader' is not valid. A minimum of one .ssdl artifact must be supplied.

当我要创建DbContext的新实例时，我已将此连接字符串传递给它：

metadata=res://*;provider=System.Data.SqlClient;provider connection string="Data Source=.;Initial Catalog=MyDb;integrated security=true;

错误明细：

System.ArgumentException was unhandled by user code
HResult=-2147024809
Message=Argument 'xmlReader' is not valid. A minimum of one .ssdl artifact must be supplied. 
Source=EntityFramework
StackTrace:
   at System.Data.Entity.Core.EntityUtil.CheckArgumentEmpty[T](IEnumerable`1& enumerableArgument,  Func`2 errorMessage, String argumentName)
   at System.Data.Entity.Core.Metadata.Edm.StoreItemCollection..ctor(IEnumerable`1 xmlReaders, IEnumerable`1 filePaths)
   at System.Data.Entity.Core.Metadata.Edm.MetadataCache.LoadStoreCollection(EdmItemCollection edmItemCollection, MetadataArtifactLoader loader)
   at System.Data.Entity.Core.Metadata.Edm.MetadataCache.<>c__DisplayClass5.<>c__DisplayClass7.<GetMetadataWorkspace>b__1()
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.LazyInitValue()
   at System.Lazy`1.get_Value()
   at System.Data.Entity.Core.Metadata.Edm.MetadataCache.<>c__DisplayClass5.<>c__DisplayClass7.<GetMetadataWorkspace>b__4()
   at System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.LoadAndCheckItemCollection[T](Func`1 itemCollectionLoader)
   at System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.<>c__DisplayClass16.<.ctor>b__f()
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.LazyInitValue()
   at System.Lazy`1.get_Value()
   at System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.GetItemCollection(DataSpace dataSpace, Boolean required)
   at System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.GetItemCollection(DataSpace dataSpace)
   at System.Data.Entity.Core.Objects.ObjectContext.InitializeMappingViewCacheFactory(DbContext owner)
   at System.Data.Entity.Core.Objects.ObjectContext..ctor(EntityConnection connection, Boolean isConnectionConstructor, ObjectQueryExecutionPlanFactory objectQueryExecutionPlanFactory, Translator translator, ColumnMapFactory columnMapFactory)
   at System.Data.Entity.Core.Objects.ObjectContext..ctor(EntityConnection connection)
   at System.Data.Entity.Internal.InternalConnection.CreateObjectContextFromConnectionModel()
   at System.Data.Entity.Internal.LazyInternalConnection.CreateObjectContextFromConnectionModel()
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.InternalContext.Initialize()
   at System.Data.Entity.Internal.LazyInternalContext.get_ObjectContext()
   at System.Data.Entity.Internal.InternalContext.ExecuteSqlQuery[TElement](String sql, Nullable`1 streaming, Object[] parameters)
   at System.Data.Entity.Internal.InternalContext.ExecuteSqlQueryAsIEnumerator[TElement](String sql, Nullable`1 streaming, Object[] parameters)
   at System.Data.Entity.Internal.InternalContext.ExecuteSqlQuery(Type elementType, String sql, Nullable`1 streaming, Object[] parameters)
   at System.Data.Entity.Internal.InternalSqlNonSetQuery.GetEnumerator()
   at System.Data.Entity.Infrastructure.DbRawSqlQuery`1.GetEnumerator()
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)
   at IdeaDataAccess.EF.EntityFrameworkQueryPerformer`1.ExecuteScalar(String query)
   at IdeaBusiness.DatabaseCore.Core`2.ExecuteScalar(String query)
   at IdeaBusiness.DatabaseCore.Facade.ExecuteScalar(String query)
   at IdeaComponent.IdeaComponent.IdeaGridView.OnRowCreated(GridViewRowEventArgs e) in D:\Solutions\IdeaCenter\Source Code\IdeaCenterV2\IdeaComponent\Components\GridView\IdeaGridView.vb:line 515
   at System.Web.UI.WebControls.GridView.CreateRow(Int32 rowIndex, Int32 dataSourceIndex, DataControlRowType rowType, DataControlRowState rowState, Boolean dataBind, Object dataItem, DataControlField[] fields, TableRowCollection rows, PagedDataSource pagedDataSource)
   at System.Web.UI.WebControls.GridView.CreateChildControls(IEnumerable dataSource, Boolean dataBinding)
   at System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data)
   at System.Web.UI.WebControls.GridView.PerformDataBinding(IEnumerable data)
   at System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data)
   at System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback)
   at System.Web.UI.WebControls.DataBoundControl.PerformSelect()
   at System.Web.UI.WebControls.BaseDataBoundControl.DataBind()
   at System.Web.UI.WebControls.GridView.DataBind()
   at WebApplication1.WebForm1.Page_Load(Object sender, EventArgs e) in C:\Users\idea\Desktop\New folder\WebForm1.aspx.vb:line 8
   at System.Web.UI.Control.OnLoad(EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   InnerException:

Answer 1

我终于找到了解决这个问题的方法。我在我的UI中添加了对EntityFramework.dll的引用，然后将典型的连接字符串传递给我的Biz层并基于此创建了一个DbContext对象，从而在DataAccess中执行了没有错误的函数。感谢你所做的一切。如果您需要了解有关我的解决方案的更多信息，请告诉我说明它

Answer 2

查看你的连接字符串，它看起来有点缺乏。这是当前项目中的一个，添加了各种换行符以便于阅读：

          <connectionStrings>
             <add name="PowerDespatchConnection" 
    connectionString="

metadata=res://*/PowerDespatch.csdl|
         res://*/PowerDespatch.ssdl|
         res://*/PowerDespatch.msl;
         provider=System.Data.SqlClient;
provider connection string=&quot;data source=athena;initial catalog=RCDev;Integrated Security=SSPI;App=EntityFramework&quot;
           " 
providerName="System.Data.EntityClient" />

您缺少csdl，ssdl和msl部分。（PowerDespatch是Model的名称。）你应该在你的EF项目文件夹下找到匹配的文件，在obj \ Debug \ edmxResourcesToEmbed中。

如果缺少这些，那么关于你如何创建模型的事情是不对的。

参数'xmlReader'无效。必须至少提供一个.ssdl工件

2 个答案: