Previewing the page designated as "latest posts" shows to the frontpage.

[joyously]

Discussion for Trac ticket https://core.trac.wordpress.org/ticket/34005
What should happen when you edit the Page designated as Latest Posts?

(Edited to add reproducing steps below)
To reproduce:

• Create two pages (let's call them "Front" and "Blog")
• Set Homepage to "Front" and Posts page to "Blog"
• Edit page 2 in editor mode
• Press preview
• Confirm you got Front instead of Blog

[karmatosed]

For now, this I think needs closing as not something we should tackle in v1 of Gutenberg. It is worthy of consideration as we iterate.

[joyously]

This issue needs to be reopened.
In the below test, I have assigned "a Blog Page" to be the page for Latest Posts, and "Page with Comments" to be the Home page.
When I edit the Blog Page, it shows the content as expected. But clicking on the Preview button shows the Page with Comments Home page, although the menu styling indicates that the Blog Page is the current page.
Tested with WP 5.3 (also got same result with GB 6.8 and GB 7.0).

[melchoyce]

Weirdly, when I try to open my Posts Page in the editor, it loads it in the Classic Editor instead of Gutenberg.

[talldan]

@joyously Please could you update the title and description of this ticket? If you can provide steps for reproduction that would be appreciated.

[youknowriad]

Closing. Let's reopen when this #2409 (comment) gets addressed.

[joyously]

Hey, I don't see the point in closing because you want a different title.
There is a problem here, and it's not fixed, so this should remain open. I clearly show what happens. What more do you need?

[youknowriad]

It's not closed because it needs a different title, it's closed because contributors didn't understand the issue and how to reproduce making the action non-actionable.

[khacoder]

So I am getting a very similar problem to joyously.
My page settings are Homepage: Frontpage and Posts page: Blog.
When in editor mode on the Blog page and I press Preview I get the Front Page and not the blog index (blog posts). So I just wanted to confirm that there is definitely a problem.

I have WordPress 5.3.2 installed. This happens with and without the Gutenberg plugin installed.

[youknowriad]

I tried again and I was actually able to replicate the issue with these steps. #2409 (comment)

[adamziel]

I tracked down why the preview shows the front page and it's a core issue. After clicking "Open preview in new tab" while editing posts page, Gutenberg redirects to a preview URL like this one:

https://mywpsite.com/?page_id=5&preview_id=5&preview_nonce=12bd60d6f4&preview=true

When you visit that URL, WordPress will load the front page instead of the posts page. This is because class-wp-query.php assumes that posts page is also the front page:

https://github.com/WordPress/WordPress/blob/b4373fafe9b87f75bf9d65e808be8049510dff8b/wp-includes/class-wp-query.php#L1032

Then, when rendering a preview, it substitutes the page_id that was requested with the value of get_option( 'page_on_front' ):

https://github.com/WordPress/WordPress/blob/b4373fafe9b87f75bf9d65e808be8049510dff8b/wp-includes/class-wp-query.php#L1904

If I remove the preview parameters and leave only ?page_id=5, it displays the correct page. It could be an okay-ish workaround since marking posts page as a draft or private doesn't actually prevent unauthenticated users from viewing it. Still, I think we should be really addressing the root cause in the core - I am going to close this one and fill a core ticket.

[adamziel]

The core ticket is available here: https://core.trac.wordpress.org/ticket/49969

[joyously]

I think you all sidetracked my original question for this issue, which was "What should the editor show when editing the Page designated as Latest Posts?"
Because the editor is WYSIWYG, should it show the actual contents of the Page (which is the current action) or should it show what is on the front end (which is the Preview-which happens to be wrong)? Perhaps this case is one way to enter into the Full Site Editor to be consistent, but that means there would be no way to edit the Page in preparation to switch it back to being a normal page.