Backend preview URL does not work

[fritzmg]

Affected version(s)

5.0.7, 5.0.x-dev

Description

If you open the preview from the back end, i.e. via an URL like

https://example.com/contao/preview?page=8

then the resulting redirect response URL will be

https://example.com\/preview.php/page-alias

which will lead to a 404 response.

For some reason this call in PageModel::getPreviewUrl

contao/core-bundle/contao/models/PageModel.php

Line 1180 in 0941be9

$strUrl = $objRouter->generate(PageRoute::PAGE_BASED_ROUTE_NAME, array(RouteObjectInterface::CONTENT_OBJECT => $this, 'parameters' => $strParams), UrlGeneratorInterface::ABSOLUTE_URL);

results in such an aforementioned URL (with the first slash "escaped").

/cc @aschempp

[ausi]

I was not able to reproduce this with Contao 5.0.7

For a request to /contao/preview?page=4
I first get a response with:
Location: /preview.php/contao/preview?page=4
and the second response with:
Location: https://example.com/preview.php/test-page.html

[fritzmg]

Hm, I can reproduce it in 5.0.7 and 5.0.x-dev.

[fritzmg]

It's an issue that only occurs under Windows, presumably. The cause is this line:

contao/core-bundle/contao/models/PageModel.php

Line 1174 in 0941be9

$context->setBaseUrl(rtrim(\dirname($baseUrl), '/') . $previewScript);

$baseUrl is /preview.php and \dirname($baseUrl) will be \.

[fritzmg]

This change was introduced here: #5195

$previewScript is /preview.php in both Contao 4.13 and 5.0 - yet for some reason we handle it differently in Contao 5? @ausi do you remember why?

[fritzmg]

My bad, I changed this here: #4326 🙈

[fritzmg]

Closing in favor of #5585