Dependency Injection in WinForms

Question

in Program.cs I add this code:

services.AddDbContext<InventoryDbContext>(context => context.UseSqlServer(constr));
services.AddScoped<IClassService, ClassService>();
services.AddScoped<ICategoryService, CategoryService>();

in MDIForm I add this code:

private readonly IClassService classService;
private readonly ICategoryService categoryService;
public MdiForm(IClassificationService classificationService, ICategoryService categoryService){
this.classService = classService;
this.categoryService = categoryService;}

then to show a category from MDI I do this code. But in order to add the classService from CategoryForm to Classification, it should be a part of CategoryForm.

 

from MDI Form to show CategoryForm:

var categoryForm = new frmCategory(classService, categoryService);
categoryForm.ShowDialog();
from CategoryForm to show ClassForm:
var classForm = new frmClass(classService);
classForm .ShowDialog();