Redirects and history

Inertia requests follow redirects with XHR, which is not always what the browser would do. Inertia.Net adjusts redirect responses so the client behaves correctly.

Redirect helpers

return Results.Redirect("/users");                 // standard redirect
return Back();                                     // Referer, else "~/" (app root, PathBase included)
return Back("/users");                             // Referer, else "/users"
return Location("https://billing.example.com");    // leave the SPA

Back() only follows a Referer that is an http(s) URL with the request's own host and port. This prevents an open redirect. The scheme is not compared, so it works behind a TLS-terminating proxy; on HTTPS an http Referer is upgraded to https.

What the middleware changes

Turn off external redirect conversion with o.ConvertExternalRedirects = false if the app intentionally redirects to another origin.

Pages without a handler

app.MapInertia("/about", "About", props);

Maps GET and HEAD to Render("About", props), like Laravel's Route::inertia.

In MVC, return this.InertiaView(props); renders the action's own component, {Controller}/{Action} by default. AddInertiaMvc(o => o.ComponentResolver = ctx => ...) changes the rule.

History encryption

builder.Services.AddInertia(o => o.EncryptHistory = true);   // every page

context.Inertia().EncryptHistory();                          // this response
context.Inertia().EncryptHistory(false);                     // opt out for this response

encryptHistory is written as true only when set and is not carried across redirects. The Inertia client encrypts its history state with the page's key.

Clearing history

app.MapPost("/logout", (HttpContext context) =>
{
    context.Inertia().ClearHistory();
    return Results.Redirect("/login");
});

clearHistory goes through the state store, applies to the next page rendered after the redirect(s), then is consumed. It is typically used before a redirect after logout.

Preserving a fragment

context.Inertia().PreserveFragment();

By default a redirect loses the URL fragment. PreserveFragment() keeps it across the next redirect. The client receives preserveFragment: true on the next page.

Page URL

The page object's url is PathBase, Path and QueryString. Behind a proxy that rewrites paths, set o.UrlResolver to return the URL the browser sees:

o.UrlResolver = ctx => ctx.Request.GetEncodedUrl();