如何在ASP.NET Razor页面中为我的CRUD操作使用多个基类

Question

I designed an ASP.NET Core Razor Pages application implementing dropdown list class and using the class as a base for Create, Read and Update classes.

Now I want to implement anonymous authentication and I have created another class for this which should ideally be the base class for the Create, Read and Update classes. When I tried to add it, the system says I cannot use 2 base classes.

How can I use multiple base classes in ASP.NET Core Razor (MVVM)

I tried using both classes but that triggered an error stating I cannot use more than one base class

My dropdown list base class

public class GLRefPageModel: PageModel
    {
        public SelectList GLRefNameSL { get; set; }

        public void PopulateGLRefDropDownList(strMaterialsTransactContext _context, object selectedGLRef = null)
        {
            var GLRefsQuery = from d in _context.GLRef
                              select d;

            GLRefNameSL = new SelectList(GLRefsQuery.AsNoTracking(), "ID", "Description", selectedGLRef);

        }
    }

My Authentication base class

public class DI_BasePageModel : PageModel
    {
        protected ApplicationDbContext Context { get; }
        protected IAuthorizationService AuthorizationService { get; }
        protected UserManager<IdentityUser> UserManager { get; }

        public DI_BasePageModel(
            ApplicationDbContext context,
            IAuthorizationService authorizationService,
            UserManager<IdentityUser> userManager) : base()
        {
            Context = context;
            UserManager = userManager;
            AuthorizationService = authorizationService;
        }
    }

My Edit Class

public class EditModel : GLRefPageModel
    {
        private readonly strMaterialsTransact.Models.strMaterialsTransactContext _context;

        public EditModel(strMaterialsTransact.Models.strMaterialsTransactContext context)
        {
            _context = context;
        }

        [BindProperty]
        public strMovement strMovement { get; set; }

        public async Task<IActionResult> OnGetAsync(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }



            if (strMovement == null)
            {
                return NotFound();
            }
            //select the current GLRef
            PopulateGLRefDropDownList(_context, strMovement.GLRefID);
            return Page();
        }

        public async Task<IActionResult> OnPostAsync(int? id)
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }

            var strMovementToUpdate = await _context.strMovement.FindAsync(id);

            if (await TryUpdateModelAsync<strMovement>(
                strMovementToUpdate,
                "strmovement", //prefix for form value
                s => s.ID, s => s.TransactionDate, s => s.QtyFromStore, s => s.IDPartNbr,
                s => s.QtyToStore, s => s.GLRefID, s => s.ShopOrder, s => s.TransactionReason, s => s.TransactionReason,
                s => s.OwnerID, s => s.TimeLastAccessed, s => s.Initials, s => s.LastUser))
            {
                await _context.SaveChangesAsync();
                return RedirectToPage("./Index");
            }

            //**Select GLRef if TryUpdateModelAsync fails
            PopulateGLRefDropDownList(_context, strMovementToUpdate.GLRefID);
            return Page();
        }
    }

I expect to me able to call the base class for my dropdown list operation in my Create, Update and Read operations and also be able to call (and use) the class for the anonymous authentication exercise

Answer 1

I have been able to solve the problem by using composition design pattern all the classes into the DI_BasePageModel class as follows:

public class DI_BasePageModel : PageModel
    {
        protected ApplicationDbContext Context { get; }
        protected IAuthorizationService AuthorizationService { get; }
        protected UserManager<IdentityUser> UserManager { get; }

        public DI_BasePageModel(
            ApplicationDbContext context,
            IAuthorizationService authorizationService,
            UserManager<IdentityUser> userManager) : base()
        {
            Context = context;
            UserManager = userManager;
            AuthorizationService = authorizationService;
        }


        public SelectList GLRefNameSL { get; set; }

        public void PopulateGLRefDropDownList(ApplicationDbContext _context,     object selectedGLRef = null)
        {
            var GLRefsQuery = from d in _context.GLRef
                              select d;

            GLRefNameSL = new SelectList(GLRefsQuery.AsNoTracking(), "GLRefID", "Description", selectedGLRef);

        }

Thanks for pointing it out Chris Pratt