I'm trying to do a web App with ASP.NET Core 3.1. I have an existing SQL Database with full of users. I have only read access to this database, so I can't change nothing. My question is, can I somehow use it to authentication to Login instead of AspNetUsers table? (I don't need registration, nor forget password, etc., just a safety login)

My User database has these columns: Id(varchar),Name(varchar),Rank(int),Password(varchar),Email(varchar),Phone(varchar)

CodePudding user response：

use it to authentication to Login instead of AspNetUsers table

Below is a demo, you can refer to it.

LoginModel

public class LoginModel
    {
        [Required]
        [Display(Name ="Username")]
        public string UserName { get; set; }
        [Required]
        [DataType(DataType.Password)]
        public string Password { get; set; }
        public bool RememberLogin { get; set; }
        public string ReturnUrl { get; set; }

    }

UserModel

public class UserModel
    {
        public int UserId { get; set; }
        public string Username { get; set; }
        public string Password { get; set; }
        public string Role { get; set; }
    }

AccountController
[Note] I set fake data, you can get it directly from the database.

public class AccountController : Controller
    {
        //Sample Users Data, it can be fetched with the use of any ORM
        public List<UserModel> users = null;
        public AccountController()
        {
            users = new List<UserModel>();
            users.Add(new UserModel() { UserId = 1, Username = "Anoop", Password = "123", Role = "Admin" });
            users.Add(new UserModel() { UserId = 2, Username = "Other", Password = "123", Role = "User" });
        }

        public IActionResult Login(string ReturnUrl = "/")
        {
            LoginModel objLoginModel = new LoginModel();
            objLoginModel.ReturnUrl = ReturnUrl;
            return View(objLoginModel);
        }
        [HttpPost]
        public async Task<IActionResult> Login(LoginModel objLoginModel)
        {
            if (ModelState.IsValid)
            {
                var user = users.Where(x => x.Username == objLoginModel.UserName && x.Password == objLoginModel.Password).FirstOrDefault();
                if (user == null)
                {
                    //Add logic here to display some message to user
                    ViewBag.Message = "Invalid Credential";
                    return View(objLoginModel);
                }
                else
                {
                    //A claim is a statement about a subject by an issuer and
                    //represent attributes of the subject that are useful in the context of authentication and authorization operations.
                    var claims = new List<Claim>() {
                    new Claim(ClaimTypes.NameIdentifier,Convert.ToString(user.UserId)),
                    new Claim(ClaimTypes.Name,user.Username),
                    new Claim(ClaimTypes.Role,user.Role),
                    new Claim("FavoriteDrink","Tea")
                    };

                    //Initialize a new instance of the ClaimsIdentity with the claims and authentication scheme
                    var identity = new ClaimsIdentity(claims, CookieAuthenticationDefaults.AuthenticationScheme);
                    //Initialize a new instance of the ClaimsPrincipal with ClaimsIdentity
                    var principal = new ClaimsPrincipal(identity);
                    //SignInAsync is a Extension method for Sign in a principal for the specified scheme.
                    //await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme,
                    //    principal, new AuthenticationProperties() { IsPersistent = objLoginModel.RememberLogin });
                    await HttpContext.SignInAsync(
                       principal, new AuthenticationProperties() { IsPersistent = objLoginModel.RememberLogin });

                    return LocalRedirect(objLoginModel.ReturnUrl);
                }
            }
            return View(objLoginModel);
        }

        public async Task<IActionResult> LogOut() {

      
            //SignOutAsync is Extension method for SignOut
            await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
            //Redirect to home page
            return LocalRedirect("/");
        }
    }

In HomeController, use [Authorize] on ConfidentialData() method

 public class HomeController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }
        [Authorize]
        public IActionResult ConfidentialData() 
        {
            return View();    
        }
    }

ConfidentialData view

@{
    ViewData["Title"] = "Confidential Data";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Confidential Data</h2>

@if (User.Identity.IsAuthenticated)
{
    <table >
        @foreach (var claim in User.Claims) {
        <tr><td>@claim.Type</td><td>@claim.Value</td></tr>
        }
    </table>
}

Register Authentication in startup

services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
                .AddCookie(x => x.LoginPath = "/account/login");

...
app.UseAuthentication();
app.UseAuthorization();

Result:

Read Use cookie authentication without ASP.NET Core Identity to know more.

Login form

@model LoginModel

@{
    ViewData["Title"] = "Login";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Login</h2>

<hr />
<div >
    <div >
        <form asp-action="Login">
            <div asp-validation-summary="ModelOnly" ></div>
            @if (!string.IsNullOrEmpty(ViewBag.Message))
            {
                <span >
                    @ViewBag.Message
                </span>
            }
            @Html.HiddenFor(x => x.ReturnUrl)
            <div >
                <label asp-for="UserName" ></label>
                <input asp-for="UserName"  />
                <span asp-validation-for="UserName" ></span>
            </div>
            <div >
                <label asp-for="Password" ></label>
                <input asp-for="Password"  />
                <span asp-validation-for="Password" ></span>
            </div>
            <div >
                <div >
                    <label>
                        <input asp-for="RememberLogin" /> @Html.DisplayNameFor(model => model.RememberLogin)
                    </label>
                </div>
            </div>
            <div >
                <input type="submit" value="Login"  />
            </div>
        </form>
    </div>
</div>