Topic on Talk:Page Previews/Flow

Tracked in Phabricator
Task T182953

I think previews are shown for links even if they are just redirects. If my previous statement is true, I recently noticed an outlier. Hovering over the w:Core memory link in an image text (A portion of a core memory with a modern flash SD card on top) in w:Random Access Memory shows the Looks like there isn't a preview for this page message in the popup.

I specify this as an outlier because in the same image text there's a link to the w:SD card article which is also redirect. Hovering over it does show a preview!

Any reasons for this odd behaviour?

It is likely due to the fact that the redirect is categorized (without a hidden category), making the intended behaviour ambiguous. Should the preview show the category or should it redirect, what about cases where it contains simple text?

In fact, a redirect is simply a page with a redirect markup. It could potentially be a full page with lots of content as long as the first section contains that markup. It is an unfortunate result of earlier developer's misguided decision to allow metadata inside a page.

In any of the following cases,

• a redirect page (that only contains #REDIRECT ...)
• a categorized redirect page
• a redirect page with simple text (is it even possible?)

I might not care if the the preview of the page to which it redirects is shown. That's because, I expect the preview to give more information than I could get from the link text. I don't think the information such as,

• categories to which the page that redirect page belongs
• simple text in the redirect page (if it's possible)

shown in the preview would be more useful than the preview of the page to which it redirects.

You're missing the point that mediawiki is an interface / software that is in a perpetual state of conflict. It attempts to cater to both readers and editors and can never really cater properly to both of them due to the inherent difference in the characteristics of those users.

Showing preview of the redirect itself may be sensible sometimes for an editor, but may not be so for a reader. Moreover, a redirect may be to the wrong target, and simply confuse both editors and readers.

Anyway, as far as this thread is concerned it seems to be a clear issue, because there are other redirects that have categories and work properly. Perhaps all it needs is a simple edit to refresh the cache.

IP I think you misread. Kaartic wasn't asking to see categories or text on the redirect page. They were merely responding to your point that it would be plausible to show categories or content on redirect pages, acknowledging that showing-something is better than a "no preview available" showing-nothing. I think we all agree the best behavior is to ignore anything on the redirect page, and just show a preview of the redirect-target page. People expect preview to show whatever clicking-the-link will show.

I tested somethings, trying to fix it:

• Purging the redirect page didn't work.
• Purging the page pointing to the redirect didn't work.
• Null-editing the redirect page didn't work.
• Null-editing the page pointing to the redirect didn't work.
• A dummy edit to the redirect did fix it!

Weird. This should definitely be investigated. It could be affecting other pages. In fact there is no clear basis to conclude that it's related to the page being a redirect. It could be affecting regular article pages.

There will always be edge cases where it makes sense to show that dialog, e.g. if it can't possibly interpret the page such as the target page of a redirect being deleted, target page never existing in the first place, no first section on a particular page, and so forth.

"No preview" seems to be shown whenever it can't interpret or read the preview. It could be caused by any number of things, e.g. an error while reading the page, or storing the summary, or simply an inability to parse the content properly.

It is probably not worth overthinking it unless it can be consistently reproduced even after a simple page edit.

A dummy edit to the redirect did fix it!

—Alsee

Now that's what I call surprising. Of course as large number of components might be involved in showing a preview, this might be something that cannot be easily tracked down. Anyways, it's up to the developers to decide. May be we should file a ticket on phab and let the developers decide for obvious reasons (they know a lot more than we do about how previews are shown).