[wp-trac] [WordPress Trac] #12859: Preview new, blank page/post creates broken preview

[WordPress Trac]

#12859: Preview new, blank page/post creates broken preview
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 Reporter:  duck_         |       Owner:                         
     Type:  defect (bug)  |      Status:  new                    
 Priority:  normal        |   Milestone:  3.0                    
Component:  General       |     Version:  3.0                    
 Severity:  normal        |    Keywords:  has-patch needs-testing
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 Steps:
 1. Add new post or page, don't add any content
 2. Click "Preview"

 Actual:
 Redirected to preview page with large number of errors.

 Expected:
 WordPress execution killed with message 'Preview not available. Please
 save as a draft first.' (2.9.2 behaviour)

 I believe this is occurring because all new pages and posts are now
 created with a postID (see r12987). Therefore the check for $post_ID < 1
 in post_preview() (wp-admin/includes/post.php, line 1288) is rendered
 ineffective.

 Instead of checking the post_ID variable I think the function should check
 for status being auto_draft. However, if this is done, after autosaving a
 title a new post will still generate this error when previewing (create
 new post, type a title, let it autosave, click preview). This is because
 in wp-admin/js/autosave.js (autosave_update_post_ID function) checks value
 of #post_ID field against the newly autosaved ID, if they're equal the
 function terminates and so #auto_draft field is not set to '0'. I think
 the check was there to stop unnecessary ajax requests, but the function no
 longer does this... removing this also has benefit of reenabling the
 publishing buttons quicker than default 5000ms.

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Ticket URL: <http://core.trac.wordpress.org/ticket/12859>
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