Precognition vary header

[apih]

Hi, just want to ask, why does the HandlePrecognitiveRequests middleware append the Vary header on the response, with Precognition value, as seen on this line, even when the request is not attempting precognition?

Maybe @timacdonald can share the reason?

[timacdonald]

Hey, @apih, the Vary header is used as a cache key to indicate that a page is different.

It needs to be on all requests for the given URL.

You can read more about it in the MDN docs: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Vary

Hope that helps.

[apih]

I am using HandlePrecognitiveRequests middleware on a resource route right now, like below, and I can see the Vary header on GET requests too.

Route::resource('products', ProductController::class)->middleware(HandlePrecognitiveRequests::class);

There are only examples for normal routes, explicitly for POST (data submission), in Precogntion documentation, so I am not sure if using the middleware on resource routes is right or not.

[timacdonald]

You may use Precognition on any request method.

[apih]

I see, thanks for the clarification.

[timacdonald]

No troubles at all.