Entity Framework: DbContext and setting the ProviderName

Question

When you derive from DbContext and use the parameter-less constructor it will load a connection string from web.config. You also have the option of explicitly specifying the

Answer 1

Try like this ,

public DBDataContext _dataContex;

public DBDataContext DBContext 
    {
        get
        {
            if (_dataContex== null)
            {
                _v= new DBDataContext(ConfigurationManager.ConnectionStrings["yourConnectinString"].ConnectionString);
            }
            return _dataContex;
        }

    }

Answer 2

Create your DbConnection manually and pass it to the DbContext constructor as follows:

var conn = DbProviderFactories.GetFactory("MY_CONN_PROVIDER").CreateConnection();
conn.ConnectionString = "MY_CONN_STR";

new DbContext(conn, true);

Notice the second parameter bool contextOwnsConnection is true. Since you don't re-use the connection elsewhere, it lets the context manage the connection and Dispose() it when needed.

Answer 3

You can get to the ObjectContext through IObjectContextAdapter:

((IObjectContextAdapter)context).ObjectContext

DbContext ("context" above) still wraps ObjectContext, so don't worry that you will have a new instance.

You can instantiate DbContext using this overload

public DbContext(ObjectContext objectContext, bool dbContextOwnsObjectContext) {}

for example:

public class YourDbContext : DbContext 
{
    public YourDbContext() : this(new YourObjectEntities(), dbContextOwnsObjectContext: true) 
    {}

}

Then you can set your connection string inside of YourObjectEntities:

public partial class YourObjectEntities : ObjectContext
{
    public const string ConnectionString = "name=YourEntities";  // Get it from somewhere

    public YourObjectEntities() : base(ConnectionString, "YourEntities")
    {
    // Some initialization, e.g. ContextOptions.LazyLoadingEnabled = false;
    }
}

How you specify the provider there is your exercise.