[SOLVED] In Auth0 can you pass custom parameters to the /authorize endpoint?

In Auth0 can you pass custom parameters to the /authorize endpoint?

I have a very similar challenge to Pass parameters into Auth0 sign up. However, the answers to that question are all outdated and point to Auth0 functionality that is end-of-life.

I have a B2C application with an owner role and a contributor role. When a user registers, I need to indicate to Auth0 which type of role they are registering for. Then I would like to use Auth0 Actions to do the Role Assignment.

If I have to use the Management API from my application, then that is already too late, as the Auth token has been created, and they won't have a role assigned until their token is refreshed.

Solution

This can be done with the AuthorizationParams class in auth0-spa-js lib.

If, like me, you are using Blazor. Then you need to do it like so:

        var parameters = new Dictionary<string, object>
        {
            {"ext-user-type", "Example"}
        };
        var options = new InteractiveRequestOptions
        {
            Interaction = InteractionType.SignIn,
            ReturnUrl = Navigation.Uri
        };
        
        options.TryAddAdditionalParameter("extraQueryParams", parameters);
        
        Navigation.NavigateToLogin("authentication/login", options);

You can then grab this in the Post Login Action in the event.request.query object.