cookiebar.js does not load when using new Twig-Template in Contao 5.6.6

[mayerthomas]

Prerequisites

• I checked for duplicate issues (open and closed)
• I am using the latest stable version/release of the Contao Cookiebar
• I made sure that my own template changes, CSS or JS do not interfere with the Contao Cookiebar
• This issue contains only one bug.
• This issue is not a question, not a feature request and I have read the documentation and pinned issues

Please select the topic(s) that most closely match your concern

Template (HTML/Twig)

What operating system(s) are you seeing the problem on?

Windows

What browser(s) are you experiencing the problem on?

Chrome, Firefox, Microsoft Edge

Description

I have a working Cookiebar-Setup with the Default-Layout in a Contao-5.6.6-installation.
When i switch to the twig-layout with slots, the Cookiebar does not show up.

Error in Chrome-Console;
Uncaught (in promise) Error: A listener indicated an asynchronous response by returning true, but the message channel closed before a response was received

Relevant log output

[zoglo]

I can confirm the issue but this is something that may or may not be easily fixed and would need some rethinking of how the cookiebar would have to be parsed.

Technical explanation

1. The reason the JavaScript is not being output is due to responses that were generated by the new twig layout not containing any content type header. You would have to additionally consider that to output the JS.

Anyways, this would most likely still not work, as you would just output the JavaScript but not the template for the cookiebar which leads to the next problem:

2. The onGeneratePage hook is not triggered as it does not exist in the new twig layouts with slots, thus the template not being output 🙃. Maybe there is another event that could be used, the consensus was to rely on the KernelRequest -> see Contao 5 and Twig compatibility #182

Fixing the JS loading problem will simply not help the cause, as you would have to rethink how the cookiebar template is also delivered to the frontend. You would most likely do that in the KernelResponseEvent but may not have any information and settings available (the page settings). Maybe it's time to add the cookiebar as a content element which can be used in the content-elements within the layout, but that would also need some preloading (to block templates on the KernelResponse) ?

Non-technical explanation

The cookiebar does not work with the modern page layouts.
You should switch back to the legacy layouts for now if you are dependent on using the cookiebar in the next time.

Estimation on when this would be fixed?

Pretty sure this is nothing that will be worked on this year or within the next time or months, especially if it's not being funded (since it's not a bug but a feature that would be needed for Contao 6 or the modern page layouts).
I am also not a maintainer anymore 😉

This is something you would have to request via info@oveleon.de and get an estimation of cost to investigate this and add compatibility with the new layouts. I guess that a change like that (e. g. adding it as a content element) may also render the cookiebar position settings unfunctional, thus, by the means of semantic versioning, would need a new major version (3.x) due to a BC (which means you would have to maintain two versions at the same time again, which is just extra work again)

[zoglo]

A hacky solution to implement the feature would be #285

[zoglo]

@mayerthomas can you confirm that the PR works and write that in here / in the pull request?

[zoglo]

@mayerthomas I closed my PR.

Whilst it will allow compatibility with Twig layouts, it's simply a hack.
I did explain in the closed PR what the proper solution would be. I do have no time to provide it, and my limited resources in my freetime are currently better allocated in other places.

As initially suggested, you should for now use the legacy layouts. If you need a proper solution, you should provide a PR or funding and contact the maintainers to do it for you.

[mayerthomas]

Nevertheless, thank you very much for your approach.

[zoglo]

@mayerthomas you can install https://packagist.org/packages/zoglo/contao-cookiebar-twig-layout-compatibility

That package decorates the KernelRequestListener as outlined in #285