You can't access the HttpContext object in Blazor Server App as the protocol used is SignalR, except for the initial request which is always HTTP, in which case, you can grab the HttpContext object (before the Blazor App is instantiated), extract values, and pass them to your Blazor App. See this answer how to do that...
You can, however, inject the AuthenticationStateProvider service into your components, and access the ClaimsPrincipal (magically converted from the WindowsPrincipal) object for the claims, as the code below demonstrate.
Copy, run and test...
@page "/"
@using System.Security.Claims;
<div>@output</div>
@if (claims.Count() > 0)
{
<table class="table">
@foreach (var claim in claims)
{
<tr>
<td>@claim.Type</td>
<td>@claim.Value</td>
</tr>
}
</table>
}
@code{
private string output;
private IList<Claim> claims;
[Inject] AuthenticationStateProvider AuthenticationStateProvider { get; set; }
protected override async Task OnInitializedAsync()
{
var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
var user = authState.User;
if (user.Identity.IsAuthenticated)
{
output = $"{user.Identity.Name} is authenticated.";
claims = user.Claims.ToList();
}
else
{
output = "The user is not authenticated.";
}
}
}
UPDATE:
Actually, there are three ways to do that. The first one above, which is not recommended, as the AuthenticationState is never updated after it has been accessed. You'll need to refresh the page to access a new instance of it.
The second way to do that is to cascade the a Task of the AuthenticationState into your component, await the Task, and then access the AuthenticationState. Here's how you can do that:
@page "/"
@code {
[CascadingParameter]
private Task<AuthenticationState> authenticationStateTask { get;
set; }
private string UserName {get; set;}
protected async override Task OnInitializedAsync()
{
// Await Task<AuthenticationState>
// and then retrieve the ClaimsPrincipal
var user = (await authenticationStateTask).User;
if (user.Identity.IsAuthenticated)
{
// Assign the user name to the
UserName = user.Identity.Name;
}
}
}
Note that Task<AuthenticationState> is cascaded by the CascadingAuthenticationState component, residing in the App component (App.razor). The CascadingAuthenticationState component
contains code that stream down the newly changed AuthenticationState, whenever it changes.
The third way is to create a class service as follow:
public class UsertService
{
private readonly AuthenticationStateProvider authProvider;
public UserService (AuthenticationStateProvider authProvider)
{
this.authProvider = authProvider;
}
public async Task<string> GetUserName()
{
var authenticationStateTask = await
authProvider.GetAuthenticationStateAsync();
var user = authenticationStateTask.User;
if (user.Identity.IsAuthenticated)
{
// Executed only when the user is authenticated
return user.Identity.Name;
}
return "User not authenticated";
}
}
Note that you may extend that class to provide other values, etc.
Now you have to add this service as Scoped in the Startup class, as follows:
public void ConfigureServices(IServiceCollection services)
{
// Code removed...
services.AddScoped<UserService>();
}
And this is how you use it in your components:
@page "/"
@inject UserService UserService
<div>Your user name: @name</div>
@code
{
private string name;
protected override async Task OnInitializedAsync()
{
name = await UserService.GetUserName();
}
}
Note: If you need more help, you may contact me through my email. See in profile...
