EF Core Context always null in BaseController

Question

I've a BaseController but when I call the functions from the child Controllers the Context is always null:

public class BaseController : Controller
{
    private readonly TheContext _tContext;
    public BaseController(TheContext tContext)
    {
        _tContext= tContext;
    }

    public BaseController() { }

    public void test()
    {
        var foo = _tContext.BAR;
    }
}

I've been dealing with this by passing the Context to the BaseControler function from the child controller.

However, I now need to use OnActionExecuting() as there is code I need to run on load for each controller which uses the BaseController, which means I can't pass it the initialized context from the child controller.