Add Or Change Identity Claims In .Net 8 Blazor Web App

Question

Hi,
In Create New Blazor Web App Project :
Check => Individual Check => .Net 8 Check => Auto Interactivew and in ApplicationUser.cs I add a property for use full name { public sting Fullname { get; set; } } but in components i want show current user full name , but how to do it ?
how to add custom claims to user and get in view component
for example : i want in component use like this:

  <AuthorizeView>
@Hello @context.User.Identity.Fullname
  </AuthorizeView>

Answer 1

Hi @Mahdi Elahi,
Here is a whole working demo:
Register.razor

 user.Fullname = "Full_"+user.UserName;   //set the fullname, just for easy testing
 var result = await UserManager.CreateAsync(user, Input.Password);

 if (!result.Succeeded)
 {
     identityErrors = result.Errors;
     return;
 }
 //add the Fullname claims
 await UserManager.AddClaimAsync(user, new System.Security.Claims.Claim("Fullname", user.Fullname));

Show full name in component:

@page "/auth"

@using Microsoft.AspNetCore.Authorization

@attribute [Authorize]

@inject AuthenticationStateProvider authenticationStateProvider

<AuthorizeView>
    <Authorized>
        <p>Hello @fullname</p>
    </Authorized>

</AuthorizeView>

@code {
    private string fullname;

    protected override async Task OnInitializedAsync()
    {
        var authState = await authenticationStateProvider.GetAuthenticationStateAsync();
        var user = authState.User;

        // Get the Fullname claim
        var fullnameClaim = user.FindFirst("Fullname");

        if (fullnameClaim != null)
        {
            fullname = fullnameClaim.Value;
        }
    }
}

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Best regards,
Rena

Answer 2

your issue is that User (and database access) are only available server side during the static pre-render. in client you use the AuthenticationStateProvider to access user information. any additional information you want must be added as a claim during authentication (see adding custom claims).

you appear to be using individual, so you are using razor pages to authenticate. you will need to write server middleware that replaces the user principal with one with the additional clams

https://stackoverflow.com/questions/53292286/is-there-a-way-to-add-claims-in-an-asp-net-core-middleware-after-authentication

your other option is to create a custom AuthenticationStateProvider that adds the claims:

https://learn.microsoft.com/en-us/aspnet/core/blazor/security/authentication-state?view=aspnetcore-9.0&pivots=server

the server state must be persisted to the client:

https://learn.microsoft.com/en-us/aspnet/core/blazor/security/?view=aspnetcore-9.0&tabs=visual-studio

server code:

builder.Services.AddRazorComponents()
    .AddInteractiveWebAssemblyComponents()
    .AddAuthenticationStateSerialization(
        options => options.SerializeAllClaims = true);

client (wasm) code:

builder.Services.AddAuthorizationCore();
builder.Services.AddCascadingAuthenticationState();
builder.Services.AddAuthenticationStateDeserialization();