Question
I have a dll that uses the Entity Framework 6 to do some database operations. I'm using a database first approach. The model and everything concerning the Entity Framework, like the connection string in the App.config, were created via the wizzard in Visual Studio.
So I compiled the dll and put it together with the corresponding .config in the folder where the application using the dll expects it.
Everything works fine until I get to the point where an actual database call is made. There I get the error:
Cannot find connection string for MyDatabaseEntity
The automatically generated connectionstring is, as I said, in the config file of the dll. I cannot change the App.config of the application. But the application hands over an object that has all the information I need to build the connection string myself. So I'm looking for a way to set the connection string in the code without relying on a config file. All the tutorials I find for a database first approach use this method though. I found a post here that says to simply give the connection string as a parameter when creating the Object like
MyDatabaseEntities = new MyDatabaseEntities(dbConnect);
but ´MyDatabaseEntities´ doesn't have a constructor that takes any parameters
public partial class MyDatabaseEntities : DbContext
{
public MyDatabaseEntities()
: base("name=MyDatabaseEntities")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}
public virtual DbSet<MyTable> MyTable { get; set; }
}
Accepted Answer
How about:
public partial class MyDatabaseEntities : DbContext
{
public MyDatabaseEntities(string connectionString)
: base(connectionString)
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}
public virtual DbSet<MyTable> MyTable { get; set; }
}
Then initialize your database like you did before:
string myConnectionString = "...";
MyDatabaseEntities = new MyDatabaseEntities(myConnectionString);
Popular Answer
I had the similar issue. My Edmx and App.Config was in a different project. My startup project was different, had 3 different connection strings, we need to choose one on the fly depending on the environment. So couldn't use a fixed connection string. I created a partial class overload of the Context.cs using the same namespace. Following was my default Context.cs;
namespace CW.Repository.DBModel
{
public partial class CWEntities : DbContext
{
public CWEntities()
: base("name=CWEntities")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}
...
...
}
}
My partial class overload;
namespace CW.Repository.DBModel
{
public partial class CWEntities : DbContext
{
public CWEntities(string ConnectionString)
: base(ConnectionString)
{
}
}
}
Lastly, as my connection strings were not for EF, I converted them to a EF connection string.
public static string GetEntityConnectionString(string connectionString)
{
var entityBuilder = new EntityConnectionStringBuilder();
// WARNING
// Check app config and set the appropriate DBModel
entityBuilder.Provider = "System.Data.SqlClient";
entityBuilder.ProviderConnectionString = connectionString + ";MultipleActiveResultSets=True;App=EntityFramework;";
entityBuilder.Metadata = @"res://*/DBModel.CWDB.csdl|res://*/DBModel.CWDB.ssdl|res://*/DBModel.CWDB.msl";
return entityBuilder.ToString();
}
Lastly, the calling
var Entity = new CWEntities(CWUtilities.GetEntityConnectionString(ConnectionString));
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