Page Manager paths should support optional arguments as well

Modified the patch so you can set the optional-flag for each page parameter (including a simple validation to not have optional parameters before required parameters).

Fixed some errors.

@stBorchert thanks for the patch.

The += was causing issues for me when parameters were not set (new ones) and throwing a fatal error. Here's an update to the patch that provides defaults for parameters and prevents the error as well as existing undefined index notices.

I am unsure of how to set the path.

My use case is group/%gid/page

What is the proper syntax for the dynamic part? Is it %, %gid, or {} as specified here: https://www.drupal.org/project/page_manager/issues/2659948

I think you use the {} syntax now
group/{group}/page

I got this ContextException with patch from #4:

Drupal\Component\Plugin\Exception\ContextException: The "string"; context is required and not present. in Drupal\Core\Plugin\Context\Context->getContextValue() (line 71 of core/lib/Drupal/Core/Plugin/Context/Context.php).
Drupal\page_manager\Controller\PageManagerController->pageTitle(Object)
call_user_func_array(Array, Array) (Line: 47)
Drupal\Core\Controller\TitleResolver->getTitle(Object, Object) (Line: 743)
token_tokens('current-page', Array, Array, Array, Object)
call_user_func_array('token_tokens', Array) (Line: 402)
...

I'm not familiar with page_manager at the development level, but as far I could see, optional argument remains as required in the context definition.

After almost 1 year of dealing with page_manager I got fully into the code. Patch reviewed with:

• Schema added
• The required parameter after optional validation moved to the parameter edit form
• Tests added
• CS review

Reverses the parameter options logic from "is required" to "is optional" to match the current default behavior that makes tests to fail.

I was getting some undefined index warnings editing argument in existing pages. Re-rolled to the lastest -dev. Interdiff fails, attached simple diff.

Whoever reads this, can you please help in reviewing the patch?. Thank's ;)

Patch applies properly to 4.0.0-beta4 and works as advertised.

Re-rolled the patch with latest dev. Also, tested with the latest release 4.0-beta5

Since the schema is changing, pretty sure this needs an update.

Re-rolled the patch with the latest dev. Also, tested with the latest release 4.0-beta6

Patch works great for me in 9.1/4.0-beta6, would be great to get this feature added. Thanks everyone!

Re-rolled for 4.0-rc1 and slightly modified to fix UI issues.

Here's a re-roll of patch #16 for the latest release (8.x-4.0-rc1) minus some doc blocks. If you want to include the doc blocks, please create a new issue for them.

Hiding @ramil g's patch because it's not passing, thanks for both trying to re-roll this!

I'm glad to see you both removed the docblocks that were added and the main reason this failed. They were a scope creep that we should try to resist but I realize it's hard too, the need to reroll is the consequence of those "clean-ups"

Moving to dev branch.

I diff'd the diffs and though some of the changes might be scope creep too I don't think they are to bad if they get in. I'll mark this RTBC in hopes it can get in before needing to re-roll again ;)

Thanks for hiding it Joel, although I do still see my post. I tried to delete it but there's no option to do it.
Sorry @berliner, we both posted less than an hour apart from each other, and I didn't see yours.

Strange, the file for #18 doesn't show up in the display. I'll see if I can kick it by hiding all other patches. Sorry @berliner seems to be a bug in d.o

Strange indeed ... Seems so arbitrary :D
That's because it got hidden in #19

@berliner, but You should be able to un-hide/display patch files that I hide, that's where I think the bug is.

Thanks for everyone's work on this! Committed!