Is there any posibility to add a db context in external class/method "on fly?" When I run the application, there is no any connection string, so I need to generate a db after typing some information(server, dbname, ect)
One way is to use the factory pattern, i.e. creating a service that will be used to create new instances of your context.
Here is an example, it is not a final solution and you will need to adapt it to your needs but it should give you an idea of the technique:
public interface IDbContextFactory
{
DbContext CreateDbContext(string connectionString);
}
public class DbContextFactory : IDbContextFactory
{
public DbContext CreateDbContext(string connectionString)
{
return new DbContext(connectionString);
}
}
Then in asp.net core, you can register the context factory and inject it in your controller:
services.AddSingleton<IDbContextFactory, DbContextFactory>();
public class SomeController
{
private IDbContextFactory contextFactory;
public SomeController(IDbContextFactory contextFactory)
{
this.contextFactory = contextFactory;
}
public IActionResult Index()
{
using(var db = contextFactory.CreateDbContext("Your connection string")) {
//Get some data
}
return View();
}
}
Instead of creating a DbContext you could combine the factory pattern with the unit of work and / or repository patterns to better separate concerns and to make sure you always dispose the context, etc...
Use new YourContext(new DbContextOptionsBuilder<YourContext>().Use...().Options)