Blazor: Redirect to Login page when there is no session / JWT token?

Question

I am trying to create a new application in Blazor and am working on authentication. I am using a JWT tokens that is stored in Local storage. When the application loads i need to

Answer 1

What I did was to write my own http service to do this.

It is called Backend and has a property for the token like this:

    public string ApiToken
    {
        get
        {
            if (!string.IsNullOrEmpty(apitoken))
                return apitoken;

            apitoken = Browser.ReadStorage("apitoken");
            return apitoken;
        }

        set
        {
            Browser.WriteStorage("apitoken", value);
        }
    }

And then in this class implement all the methods that the http class has, while injecting your token. for instance:

    public async Task GetJsonAsync(string uri)
    {
            this.InProgress = true;
            var result = await http.GetJsonAsync>(uri, this.ApiToken);
            this.InProgress = false;

            if (!result.Success)
            {
                BlazorExtensions.Browser.Alert($"Error: {result.ErrorMessage}");
                return default(T);
            }

            return result.ValueObject;

    }

And everywhere use the backend service to do your requests. Also handy for your api url.

EDIT For the redirection part: For brevity I left out this part, but this is the full method:

    public async Task GetJsonAsync(string uri)
    {
        try
        {
            this.InProgress = true;
            var result = await http.GetJsonAsync>(uri, this.ApiToken);
            this.InProgress = false;

            if (!result.Success)
            {
                BlazorExtensions.Browser.Alert($"Error: {result.ErrorMessage}");
                return default(T);
            }

            return result.ValueObject;
        }
        catch (UnauthorizedAccessException)
        {
            this.InProgress = false;
            uriHelper.NavigateTo("/bzr/Logon");
            return default(T);
        }
        catch (Exception e)
        {
            BlazorExtensions.Browser.Alert($"Fout bij http fetch: {e.Message}");
            this.InProgress = false;
            return default(T);
        }
    }

The uriHelper is simply injected in the constructor:

    public IUriHelper uriHelper { get; private set; }

    public Backend(HttpClient httpInstance, IUriHelper uriHelper)
    {
        http = httpInstance;
        this.uriHelper = uriHelper;

Guess that's what you need?