ConnectionString属性尚未初始化实体框架

Question

底层提供程序在Open上失败。

  

错误简述：ConnectionString属性尚未初始化   错误内部描述：
  在System.Data.Entity.Core.EntityClient.EntityConnection.Open（）
  在System.Data.Entity.Core.Objects.ObjectContext.EnsureConnection（Boolean shouldMonitorTransactions）      在System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction [T]（Func 1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess) at System.Data.Entity.Core.Objects.ObjectQuery 1.＆lt;＆gt; c__DisplayClass7.b__5（）      at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute [TResult]（Func 1 operation) at System.Data.Entity.Core.Objects.ObjectQuery 1.GetResults（Nullable 1 forMergeOption) at System.Data.Entity.Core.Objects.ObjectQuery 1..GetEnumerator＆gt; b__0（）      在System.Data.Entity.Internal.LazyEnumerator 1.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable 1来源）      在System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.b__1 [TResult]（IEnumerable 1 sequence) at System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.ExecuteSingle[TResult](IEnumerable 1查询，表达式queryRoot）      at System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute [TResult]（表达式表达式）      at System.Data.Entity.Internal.Linq.DbQueryProvider.Execute [TResult]（表达式表达式）      在System.Linq.Queryable.FirstOrDefault [TSource]（IQueryable 1 source) at SKAI.BusinessLayer.AnalysisTreatmentBL.GetAdviceDetails(Int32 KeywordId) at SKAI_Dev.Controllers.Analysis.KeywordAnalysisController.GetNeedAdviceDetails(Int32 KeywordId) at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary 2个参数）      在System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod（ControllerContext controllerContext，ActionDescriptor actionDescriptor，IDictionary 2 parameters) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult 2.CallEndDelegate（IAsyncResult asyncResult）      在System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase 1.End() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult 1.CallEndDelegate（IAsyncResult asyncResult）      在System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End（）      在System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters（IAsyncResult asyncResult）      在System.Web.Mvc.Async.AsyncControllerActionInvoker。＆lt;＆gt; c__DisplayClass21。＆lt;＆gt; c__DisplayClass2b.b__1c（）      在System.Web.Mvc.Async.AsyncControllerActionInvoker。＆lt;＆gt; c__DisplayClass21.b__1e（IAsyncResult asyncResult）