JWT doesn't get stored in ASP.NET Core with Blazor
What am I missing for my user to be authenticated? Doesn't Microsoft.AspNetCore.Authentication.JwtBearer handle the client part (storing the token)?
The JwtBearer runs on server side , it will only validate the authorization header of request, namely Authorization: Bearer your_access_token, and won't care about how you WebAssembly codes runs . So you need send the request with a jwt accessToken . Since the tutorial suggests you should use localStorage , let's store the accessToken with localStorage .
Because WebAssembly has no access to BOM yet, we need some javascript codes served as glue . To do that, add a helper.js under the JwtAuthentication.Client/wwwroot/js/ :
var wasmHelper = {};
wasmHelper.ACCESS_TOKEN_KEY ="__access_token__";
wasmHelper.saveAccessToken = function (tokenStr) {
localStorage.setItem(wasmHelper.ACCESS_TOKEN_KEY,tokenStr);
};
wasmHelper.getAccessToken = function () {
return localStorage.getItem(wasmHelper.ACCESS_TOKEN_KEY);
};
And reference the script in your JwtAuthentication.Client/wwwroot/index.html
<body>
<app>Loading...</app>
<script src="js/helper.js"></script>
<script src="_framework/blazor.webassembly.js"></script>
</body>
Now, let's wrap the javascript codes into C# . Create a new file Client/Services/TokenService.cs:
public class TokenService
{
public Task SaveAccessToken(string accessToken) {
return JSRuntime.Current.InvokeAsync<object>("wasmHelper.saveAccessToken",accessToken);
}
public Task<string> GetAccessToken() {
return JSRuntime.Current.InvokeAsync<string>("wasmHelper.getAccessToken");
}
}
Register this service by :
// file: Startup.cs
services.AddSingleton<TokenService>(myTokenService);
And now we can inject the TokenService into Login.cshtml and use it to save token :
@using JwtAuthentication.Client.Services
// ...
@page "/login"
// ...
@inject TokenService tokenService
// ...
@functions {
public string Email { get; set; } = "";
public string Password { get; set; } = "";
public string Token { get; set; } = "";
/// <summary>
/// response from server
/// </summary>
private class TokenResponse{
public string Token;
}
private async Task SubmitForm()
{
var vm = new TokenViewModel
{
Email = Email,
Password = Password
};
var response = await Http.PostJsonAsync<TokenResponse>("http://localhost:57778/api/Token", vm);
await tokenService.SaveAccessToken(response.Token);
}
}
Let's say you want to send data within FetchData.cshtml
@functions {
WeatherForecast[] forecasts;
protected override async Task OnInitAsync()
{
var token = await tokenService.GetAccessToken();
Http.DefaultRequestHeaders.Add("Authorization",String.Format("Bearer {0} ",token));
forecasts = await Http.GetJsonAsync<WeatherForecast[]>("api/SampleData/WeatherForecasts");
}
}
and the result will be :
Apologies in advance as this is somewhat responding to a previous answer, but I don't have the rep to comment on that.
If it helps anyone else who was similarly looking for a solution to using JWT in a Blazor app, I found @itminus answer incredibly useful, but it also pointed me to another course.
One problem I found was that calling FetchData.cshtml a second time would blow up when it tries to add the Authorization header a second time.
Instead of adding the default header there, I added it to the HttpClient singleton after a successful login (which I believe Blazor creates for you automatically). So changing SubmitForm in Login.cshtml from @itminus' answer.
protected async Task SubmitForm()
{
// Remove any existing Authorization headers
Http.DefaultRequestHeaders.Remove("Authorization");
TokenViewModel vm = new TokenViewModel()
{
Email = Email,
Password = Password
};
TokenResponse response = await Http.PostJsonAsync<TokenResponse>("api/Token/Login", vm);
// Now add the token to the Http singleton
Http.DefaultRequestHeaders.Add("Authorization", string.Format("Bearer {0} ", response.Token));
}
Then I realised, than as I'm building a SPA, so I didn't need to persist the token across requests at all - it's just in attached to the HttpClient.
The following class handle the login process on the client, storing the JWT token in local storage. Note: It is the developer responsibility to store the JWT token, and passes it to the server. The client (Blazor, Angular, etc.) does not do that for him automatically.
public class SignInManager
{
// Receive 'http' instance from DI
private readonly HttpClient http;
public SignInManager(HttpClient http)
{
this.http = http;
}
[Inject]
protected LocalStorage localStorage;
public bool IsAuthenticated()
{
var token = localStorage.GetItem<string>("token");
return (token != null);
}
public string getToken()
{
return localStorage.GetItem<string>("token");
}
public void Clear()
{
localStorage.Clear();
}
// model.Email, model.Password, model.RememberMe, lockoutOnFailure: false
public async Task<bool> PasswordSignInAsync(LoginViewModel model)
{
SearchInProgress = true;
NotifyStateChanged();
var result = await http.PostJsonAsync<Object>("/api/Account", model);
if (result)// result.Succeeded
{
_logger.LogInformation("User logged in.");
// Save the JWT token in the LocalStorage
// https://github.com/BlazorExtensions/Storage
await localStorage.SetItem<Object>("token", result);
// Returns true to indicate the user has been logged in and the JWT token
// is saved on the user browser
return true;
}
}
}
// This is how you call your Web API, sending it the JWT token for // the current user
public async Task<IList<Profile>> GetProfiles()
{
SearchInProgress = true;
NotifyStateChanged();
var token = signInManager.getToken();
if (token == null) {
throw new ArgumentNullException(nameof(AppState)); //"No token";
}
this.http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
// .set('Content-Type', 'application/json')
// this.http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
Profiles = await this.http.GetJsonAsync<Profile[]>("/api/Profiles");
SearchInProgress = false;
NotifyStateChanged();
}
// You also have to set the Startup class on the client as follows:
public void ConfigureServices(IServiceCollection services)
{
// Add Blazor.Extensions.Storage
// Both SessionStorage and LocalStorage are registered
// https://github.com/BlazorExtensions/Storage
**services.AddStorage();**
...
}
// Generally speaking this is what you've got to do on the client. // On the server, you've got to have a method, say in the Account controller, whose function is to generate the JWT token, you've to configure the JWT middleware, to annotate your controllers with the necessary attribute, as for instance:
[Authorize(AuthenticationSchemes = JwtBearerDefaults.AuthenticationScheme)]
and so on...
Hope this helps...