在MVC项目中具有Entity Framework代码优先数据库。 向解决方案添加了控制台项目，但无法连接到数据库

Question

I have an MVC project in which I used Entity Framework code first approach to create my database. The database exists and I can query it from my MVC project without any issues.

Now, I added a console project to the solution. Within this console project I added a reference to my MVC project, added Entity Framework NuGet package and added the connection string from web.config (in the MVC project) into app.config (in the console project).

The connection string is:

<connectionStrings>
    <add name="TradeManagerContext" connectionString="Data Source=(localdb)\MSSQLLocalDB; Initial Catalog=TradeManagerDB; Integrated Security=True; MultipleActiveResultSets=True; AttachDbFilename=|DataDirectory|TradeManagerDB.mdf" providerName="System.Data.SqlClient" />
  </connectionStrings>

I verified that this is the connection string being used in the console app with this debugging code:

System.Console.WriteLine("ConnectionString=" + db.Database.Connection.ConnectionString);

When my console app attempts to query the database:

var result = db.Trades.Where(c => c.Ticker == "AAPL");

That line throws an exception with message:

Cannot attach the file 'C:\\Users\\RED\\documents\\visual studio 2015\\Projects\\TradeManager\\Console\\bin\\Debug\\TradeManagerDB.mdf' as database 'TradeManagerDB'.

Any ideas on what this exception means and how I can resolve it?

Here is the full stack trace:

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.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource 1 retry, DbConnectionOptions userOptions) at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource 1 retry) at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource 1 retry) at System.Data.SqlClient.SqlConnection.Open() at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.b__36(DbConnection t, DbConnectionInterceptionContext c) at System.Data.Entity.Infrastructure.Interception.InternalDispatcher 1.Dispatch[TTarget,TInterceptionContext](TTarget target, Action 2 operation, TInterceptionContext interceptionContext, Action 3 executing, Action 3 executed) at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext) at System.Data.Entity.Core.EntityClient.EntityConnection.b__2()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.b__0() at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation) at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation) at System.Data.Entity.Core.EntityClient.EntityConnection.Open()

Answer 1

It is trying to load the file TradeManagerDB from the App_Data folder. You need to use a different syntax to load it from elsewhere.