I need to add a global filter to a repository entity, i.e. it has to be applied everywhere this entity is accessed on Application service layer. My filter contains two conditions. Whereas adding the first condition, which depends on a constant, is easy and applied in OnModelCreating using HasQueryFilter, I have no idea how to apply automatically the second one, which depends on the currently selected (or default) UI language.
Use dependency injection via constructor in your DbContext class. Set the currently selected UI language inside the class implementing the interface. Use the injected implementation in the OnModelCreating method to apply the filter globally with .HasQueryFilter() method like you normally would.
If you're using something like a .NET Core API, you could build a middleware that determines the language of the current incoming request. I guess the same will work for MVC too.