Passing tokens to a server-side Blazor application

• Authenticate your application as you would do with a regular mvc/razor pages application.
• Provision and save the tokens to the authentication cookie
• Define a class to pass in the initial settings for the application:

namespace BlazorServerAuthWithAzureActiveDirectory.Data
{
    public class InitialApplicationState
    {
        public string AccessToken { get; set; }

        public string RefreshToken { get; set; }
    }
}

Define a scoped service that can be used within the Blazor application to resolve the settings from DI

using System;
using System.Security.Claims;
using System.Threading.Tasks;

namespace BlazorServerAuthWithAzureActiveDirectory
{
    public class TokenProvider
    {
        public string AccessToken { get; set; }
        public string RefreshToken { get; set; }
    }
}

On startup

services.AddScoped<TokenProvider>();

On the _Host cshtml, create and instance of InitialApplicationState and pass that as a parameter to the app:

    @{
        var tokens = new InitialApplicationState
        {
            AccessToken = await HttpContext.GetTokenAsync("access_token"),
            RefreshToken = await HttpContext.GetTokenAsync("refresh_token")
        };
    }


    <app>
        <component type="typeof(App)" param-InitialState="tokens" render-mode="ServerPrerendered" />
    </app>

On the app component resolve the service and initialize it with the data from the parameter

@using BlazorServerAuthWithAzureActiveDirectory.Data
@inject TokenProvider TokensProvider
...
@code{
    [Parameter] public InitialApplicationState InitialState { get; set; }


    protected override Task OnInitializedAsync()
    {
        TokensProvider.AccessToken = InitialState.AccessToken;
        TokensProvider.RefreshToken = InitialState.RefreshToken;


        return base.OnInitializedAsync();
    }
}

On your service, inject the token provider and retrieve the token to call the API:

public class WeatherForecastService
{
    private readonly TokenProvider _store;


    public WeatherForecastService(IHttpClientFactory clientFactory, TokenProvider tokenProvider)
    {
        Client = clientFactory.CreateClient();
        _store = tokenProvider;
    }


    public HttpClient Client { get; }


    public async Task<WeatherForecast[]> GetForecastAsync(DateTime startDate)
    {
        var token = _store.AccessToken;
        var request = new HttpRequestMessage(HttpMethod.Get, "https://localhost:5003/WeatherForecast");
        request.Headers.Add("Authorization", $"Bearer {token}");
        var response = await Client.SendAsync(request);
        response.EnsureSuccessStatusCode();


        return await response.Content.ReadAsAsync<WeatherForecast[]>();
    }
}