HttpContext.SignInAsync does not work when you consume it through .razor page

I implement ASP.NET Core cookie Authentication In blazor server side. I write simple API Controller with Login endpoint.

When I post to API via postman everything works fine and I become identified and Authorized.

When I post via HttpClient: _http.PostJsonAsync<bool>("api/auth/Login", credentials);

I hit the API endpoint and its run to till end without error but the Authentication State don't change and no cookie is created.

var res = await _http.PostJsonAsync<bool>("api/v1/Auth/Login", credentials);

api:

[AllowAnonymous]
[HttpPost]
[Route("Login")]
public async Task<bool> Login()
{
  const string Issuer = "mydomain.com";
  var claims = new List<Claim>
  {
    new Claim("ID", dataTable.Rows[0]["ID"].ToString(), ClaimValueTypes.String, Issuer),
    new Claim("FullName", dataTable.Rows[0]["FullName"].ToString(), ClaimValueTypes.String, Issuer),
    new Claim("CompanyName", dataTable.Rows[0]["CompanyName"].ToString(), ClaimValueTypes.String, Issuer),
    new Claim("Email", dataTable.Rows[0]["Email"].ToString(), ClaimValueTypes.String, Issuer),
  };

  var userIdentity = new ClaimsIdentity(claims, "User");
  var userPrincipal = new ClaimsPrincipal(userIdentity);

  await HttpContext.SignInAsync
  (
    CookieAuthenticationDefaults.AuthenticationScheme,
    userPrincipal,
    new AuthenticationProperties
    {
      ExpiresUtc = DateTime.UtcNow.AddMinutes(20),
      IsPersistent = false,
      AllowRefresh = false
    }
  );

  return true;

}

There are two solution for your problem:

1. Place a call to the login method in a page that is loading;that is,in the event OnInitAsync, but this is not useful because you probably want it to execute when a button is clicked...

2. This is the solution you are looking for: Using A Redirect Login Page. This is from the referenced link below:

   await HttpContext.SignInAsync( CookieAuthenticationDefaults.AuthenticationScheme, new ClaimsPrincipal(claimsIdentity), authProperties);

Can only be set if we start a new http request. This is achieved by redirecting the user to the page that sets the user.

See full article: Demonstration of Simple Server side Blazor Cookie Authentication [this link is outofdate]