Title: $_POST data cannot be retrieved/is empty?
Last modified: December 17, 2016

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# $_POST data cannot be retrieved/is empty?

 *  Resolved [marliesprins](https://wordpress.org/support/users/marliesprins/)
 * (@marliesprins)
 * [9 years, 5 months ago](https://wordpress.org/support/topic/_post-data-cannot-be-retrievedis-empty/)
 * Hello, I am encountering a problem I can’t seem to solve…
 * I created a custom post type for an agenda, where a band can enter their shows.
   It is important that the date of the show is entered in the following format:
   dd-mm-yyyy. I check the date with preg_match, and if the date is entered in any
   other format, the post isn’t saved. I use this code for this in the function 
   that is hooked to the save_post hook:
 *     ```
       if ( !preg_match( "/\d\d-\d\d-\d\d\d\d/", $_POST[ 'topsecreet_agenda_datumoptreden' ] ) ){
   
           return $post_id;
   
       }
       ```
   
 * However, if I use this code there is still a default wordpress message that says
   that the post is saved (though it is not), and I’d also like to add a custom 
   message to the formfield itself, providing additional information tp the user.
 * The problem is that I fail to find a way to get the information I need for this
   into the function that creates the metafields. If I use ( isset ( $_POST[ ‘topsecreet_agenda_datumoptreden’]))
   it keeps returning false. So I assume the $_POST data gets lost somewhere between
   the submit button and the reload of the page… Is there a way to pass it on so
   I can re-use it for display in the meta-boxes?

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * (@bcworkz)
 * [9 years, 5 months ago](https://wordpress.org/support/topic/_post-data-cannot-be-retrievedis-empty/#post-8563725)
 * I don’t see how that code would prevent a post save, but I suppose it’s beside
   the point if it works for you. I think WP does a redirect in order to pass a 
   message URL parameter that tells the post edit screen what message to display.
   If you can identify where this redirect occurs and where the URL parameter is
   added, you can influence what message is displayed to the user. The messages 
   themselves can be managed through the ‘post_updated_messages’ filter.
 * When a redirect occurs the values in $_POST are discarded, so before then you
   need to save that value somehow for use later. There’s several ways to save data
   so it persists between requests and redirects. Using a cookie is one option. 
   Perhaps the best option for you would be a session variable. Data can also be
   saved in the DB. Transients are a temporary form of DB storage. For all it matters
   you could store values semi-permanently in user or post meta, but that’s probably
   overkill.
 *  Thread Starter [marliesprins](https://wordpress.org/support/users/marliesprins/)
 * (@marliesprins)
 * [9 years, 5 months ago](https://wordpress.org/support/topic/_post-data-cannot-be-retrievedis-empty/#post-8563929)
 * Thanks for answering!
 * I looked into what you said and I think I am going for a transient. (never heard
   of it before but it seems the sensible choice, from what I am reading about it)
   I was hoping to avoid using the database but there doesn’t seem to be any other
   option. Using a session variable would be great but I read it can potentially
   cause a lot of trouble in wordpress so I rather not.
 * I am a bit surprised there isn’t an easier way to verify input in custom meta
   fields though. But at least I can finish the custom post type now. Thanks 🙂
 * By the way, return ends the execution of all code in a function, so everything
   that comes after a return is never executed. That’s why it’s not saved. (the 
   code that actually saves the metadata comes after all the verification checks)
   I used $postid as a parameter because all other safety measures commonly used
   in custom post types(autosave, error with nonsefields, wrong capabilities) seem
   to use it.
    BUt since you mention a redirect, I guess the postid is passed here
   to get back to the right post.

Viewing 2 replies - 1 through 2 (of 2 total)

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## Tags

 * [post data](https://wordpress.org/support/topic-tag/post-data/)

 * In: [Hacks](https://wordpress.org/support/forum/plugins-and-hacks/hacks/)
 * 2 replies
 * 2 participants
 * Last reply from: [marliesprins](https://wordpress.org/support/users/marliesprins/)
 * Last activity: [9 years, 5 months ago](https://wordpress.org/support/topic/_post-data-cannot-be-retrievedis-empty/#post-8563929)
 * Status: resolved

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