A new modern approach as articulated here is adviced in such scenarios.
If you're familiar with the TransactionScope class, then you already know how to use a DbContextScope. They're very similar in essence - the only difference is that DbContextScope creates and manages DbContext instances instead of database transactions. But just like TransactionScope, DbContextScope is ambient, can be nested, can have its nesting behaviour disabled and works fine with async execution flows.
public void MarkUserAsPremium(Guid userId)
{
using (var dbContextScope = _dbContextScopeFactory.Create())
{
var user = _userRepository.Get(userId);
user.IsPremiumUser = true;
dbContextScope.SaveChanges();
}
}
Within a DbContextScope, you can access the DbContext instances that the scope manages in two ways. You can get them via the DbContextScope.DbContexts property like this:
public void SomeServiceMethod(Guid userId)
{
using (var dbContextScope = _dbContextScopeFactory.Create())
{
var user = dbContextScope.DbContexts.Get<MyDbContext>.Set<User>.Find(userId);
[...]
dbContextScope.SaveChanges();
}
}
But that's of course only available in the method that created the DbContextScope. If you need to access the ambient DbContext instances anywhere else (e.g. in a repository class), you can just take a dependency on IAmbientDbContextLocator, which you would use like this:
public class UserRepository : IUserRepository
{
private readonly IAmbientDbContextLocator _contextLocator;
public UserRepository(IAmbientDbContextLocator contextLocator)
{
if (contextLocator == null) throw new ArgumentNullException("contextLocator");
_contextLocator = contextLocator;
}
public User Get(Guid userId)
{
return _contextLocator.Get<MyDbContext>.Set<User>().Find(userId);
}
}
