c# - Error cast object of type in Blazor server app on .NET 6 session - Stack Overflow

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I'm using Entity Framework Core to validate the user and password from the database, but when I try to declare a var authenticationExt using polymorphism because the class inherited from authenticationProvider, the debugger says:

System.InvalidCastException: Unable to cast object of type 'Microsoft.AspNetCore.Components.Server.ServerAuthenticationStateProvider' to type 'Blazor_Server_App_Login.Extensions.AuthenticationExt'

I extracted this same code from a project in .NET 7. Any suggestions?

@page "/"
@layout LoginLayout

@inject HttpClient httpClient
@using Blazor_Server_App_Login.Extensions
@using Blazor_Server_App_Login.Shared
@using Blazor_Server_App_Login.Login
@using Microsoft.AspNetCore.Components.Authorization
@inject AuthenticationStateProvider authenticationProvider
@inject NavigationManager navManager

<div class="row mt-5">
    <div class="col-lg-4 offset-lg-4 border">
        <div class="mb-3 text-center">
            <h3>LOGIN</h3>
        </div>
        <div class="mb-3">
            <label>Email</label>
            <input @bind="login.email" class="form-control" />
        </div>
        <div class="mb-3">
            <label>Password</label>
            <input @bind="login.password" class="form-control" />
        </div>
        <div class="mb-3">
            <button @onclick="IniciarSesion" class="btn btn-primary">Login</button>
        </div>

    </div>

</div>

@code {
    private UserLogin login = new UserLogin();
    private async Task IniciarSesion()
    {
        var loginResponse = await httpClient.PostAsJsonAsync<UserLogin>("https://localhost:7146/api/User/Login", login);
        if (loginResponse.IsSuccessStatusCode)
        {
            // AuthenticationStateProvider i = new AuthenticationExt();
            var sesionUser = await loginResponse.Content.ReadFromJsonAsync<SessionState>();
            var autenticationExt = (AuthenticationExt)authenticationProvider;
            await autenticationExt.UdateAuthState(sesionUser);
            navManager.NavigateTo("/Index");
        }
    }
}

Full code at:

I'm using Entity Framework Core to validate the user and password from the database, but when I try to declare a var authenticationExt using polymorphism because the class inherited from authenticationProvider, the debugger says:

System.InvalidCastException: Unable to cast object of type 'Microsoft.AspNetCore.Components.Server.ServerAuthenticationStateProvider' to type 'Blazor_Server_App_Login.Extensions.AuthenticationExt'

I extracted this same code from a project in .NET 7. Any suggestions?

@page "/"
@layout LoginLayout

@inject HttpClient httpClient
@using Blazor_Server_App_Login.Extensions
@using Blazor_Server_App_Login.Shared
@using Blazor_Server_App_Login.Login
@using Microsoft.AspNetCore.Components.Authorization
@inject AuthenticationStateProvider authenticationProvider
@inject NavigationManager navManager

<div class="row mt-5">
    <div class="col-lg-4 offset-lg-4 border">
        <div class="mb-3 text-center">
            <h3>LOGIN</h3>
        </div>
        <div class="mb-3">
            <label>Email</label>
            <input @bind="login.email" class="form-control" />
        </div>
        <div class="mb-3">
            <label>Password</label>
            <input @bind="login.password" class="form-control" />
        </div>
        <div class="mb-3">
            <button @onclick="IniciarSesion" class="btn btn-primary">Login</button>
        </div>

    </div>

</div>

@code {
    private UserLogin login = new UserLogin();
    private async Task IniciarSesion()
    {
        var loginResponse = await httpClient.PostAsJsonAsync<UserLogin>("https://localhost:7146/api/User/Login", login);
        if (loginResponse.IsSuccessStatusCode)
        {
            // AuthenticationStateProvider i = new AuthenticationExt();
            var sesionUser = await loginResponse.Content.ReadFromJsonAsync<SessionState>();
            var autenticationExt = (AuthenticationExt)authenticationProvider;
            await autenticationExt.UdateAuthState(sesionUser);
            navManager.NavigateTo("/Index");
        }
    }
}

Full code at: https://github.com/bonfildev/Blazor-Server-App-Login

• c#
• .net-core
• blazor
• polymorphism
• session-state-provider

Share Improve this question Follow edited Nov 23, 2024 at 9:31 Henk Holterman 273k3232 gold badges348348 silver badges533533 bronze badges asked Nov 22, 2024 at 21:21 Diego BonfilDiego Bonfil 3155 bronze badges 1

• It is not clear why the type-cast should be valid. We need to see how you register AuthenticationStateProvider in the DI services. – Henk Holterman Commented Nov 23, 2024 at 9:35

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1 Answer 1

Sorted by: Reset to default 1

I checked your codes on github

modify the order of the services follow this document :

    builder.Services.AddServerSideBlazor();
    //make sure your AuthenticationStateProvider is registered after basic blazor services registered by `AddServerSideBlazor` method
    builder.Services.AddScoped<AuthenticationStateProvider, AuthenticationExt>();
    //remove the codes below
    //builder.Services.AddScoped<AuthenticationExt>();

Since you injected ISessionStorage in your AuthenticationStateProvider

modify

<component type="typeof(App)" render-mode="ServerPrerendered" />

to

<component type="typeof(App)" render-mode="Server" />

so that you could avoid JavaScript interop exception,see document related

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