Messages are generated too early [#982814]

The $messages variable for page.tpl.php is generated too early in the process.

The most simple improvement is to move the generation of $messages into template_process_page() (instead of preprocess).

And when doing that, we can additionally apply the current model of process variables for consistency, which adds the benefit of allowing a contributed module to plug in an advanced rendering mechanism for $messages (i.e., a #post_render alike string/token replacement solution).

Comment	File	Size	Author
#1	drupal.messages.1.patch	1.32 KB	sun
#1
	drupal.messages.0.patch	1.57 KB	sun

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Comments

Comment #1

sun

German

Karlsruhe

CreditAttribution: sun commented 27 November 2010 at 02:21

File	Size
drupal.messages.1.patch	1.32 KB

Shortened that comment.

Comment #2

moshe weitzman CreditAttribution: moshe weitzman commented 27 November 2010 at 02:26

Status:

Needs review

» Reviewed & tested by the community

Unlike kindergarten, drupal code likes to go last. This change makes sense.

Comment #3

sun

German

Karlsruhe

CreditAttribution: sun commented 27 November 2010 at 02:32

Priority:

Major

» Normal

Comment #4

sun

German

Karlsruhe

CreditAttribution: sun commented 27 November 2010 at 16:19

Title:	Messages have to be generated last + allow for advanced ESI solutions	» Messages are generated too early
Priority:	Normal	» Major
Issue tags:		+API change

Problem

Status/error messages triggered in MODULE_preprocess_page() and THEME_preprocess_page() are not displayed.

Goal

Generate and render status/error messages as late as possible.

Details

The $messages variable is generated relatively early in template_preprocess_page() already.
The generated/rendered variable only contains messages that have been set so far.
Any messages that are triggered/set in later preprocess hooks are not output (resp. output on the next page request instead of the current).
At least for themes, it may be relatively common to use THEME_preprocess_page() to output a message on certain pages.

Notes

This patch only accounts for messages being output in later preprocess hooks. Messages triggered in process hooks or during render($variable) within the template file itself are still not captured.
I don't think it makes sense to test this change, as we are still doing the identical thing, just slightly later in time. We need to find a proper solution for this in D8.

API impact

Currently, it is technically possible to alter messages in hook_preprocess_page(). Modules or themes that are implementing this hook in order to alter status/error messages need to implement hook_process_page() instead.

Comment #5

Dries CreditAttribution: Dries commented 27 November 2010 at 19:57

This make sense to me. That said, I can't think of an actual use case where a preprocess function would generate a status message. That being said, it is easy enough to create such an example.

Comment #6

webchick

she/they

English

Vancouver 🇨🇦

CreditAttribution: webchick commented 29 November 2010 at 03:02

Dries, I'm not sure what to do with this based on your comment in #5. Leaving it to you.

Comment #7

sun

German

Karlsruhe

CreditAttribution: sun commented 29 November 2010 at 03:23

Some further notes:

- The outlined API change impact, although being true, can be considered moot, because $messages is a HTML string already, so all that a hook_preprocess_page() is able to do with regard to $messages is performing crazy-strange string replacements.

- Messages also means error messages. That's the primary reason for why I think this patch is important.