Title: Headers and Saving Post Data
Last modified: August 21, 2016

---

# Headers and Saving Post Data

 *  [Timothy Jacobs](https://wordpress.org/support/users/timothyblynjacobs/)
 * (@timothyblynjacobs)
 * [13 years, 1 month ago](https://wordpress.org/support/topic/headers-and-saving-post-data/)
 * I have been staring at this code for the past hour trying to figure out what 
   is wrong. I keep getting thrown headers already sent errors, but I can’t seem
   to find what is triggering them. If I comment out this section of code everything
   works, so I am pretty sure it is something here.
 * Any help would be greatly appreciated.
 *     ```
       add_action('save_post', 'tj_testimonials_cats_box_save');
   
       function tj_testimonials_cats_box_save($post_id)
       {
           $args = array(
               'post_type' => 'testimonials',
               'post_status' => 'publish'
           );
           $testimonials = get_posts($args);
   
           $testimonials_display = array(); 
   
           foreach ($testimonials as $testimonial) {
               $id = $testimonial->ID;
               if (isset($_POST[$id])) {
                   $testimonials_display[$id] = $_POST[$id];
               }
               else {
                   $testimonials_display[$id] = 0;
               }
           }
           update_post_meta($post_id, 'tj_testimonials_on_page', $testimonials_display);
       }
       ```
   
 * Here is the error
 *     ```
       Warning: array_map() [function.array-map]: Argument #2 should be an array in /home/content/14/10762214/html/wp-includes/post.php on line 1918
   
       Warning: Cannot modify header information - headers already sent by (output started at /home/content/14/10762214/html/wp-includes/post.php:1918) in /home/content/14/10762214/html/wp-includes/pluggable.php on line 877
       ```
   

Viewing 4 replies - 1 through 4 (of 4 total)

 *  Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * (@bcworkz)
 * [13 years, 1 month ago](https://wordpress.org/support/topic/headers-and-saving-post-data/#post-3705178)
 * I suspect the error messages are a knock on effect from the actual error so are
   useless in locating the true fault. Line 1918 in post.php does not even remotely
   match up with the error messages.
 * Just looking at your action function, I would question assigning $id an integer(
   $testimonial->ID is an integer). It is illogical to me to expect $_POST to be
   indexed by integers in any meaningful way. I believe you end up with $testimonials_display
   being an indexed array (I would expect an associative array) of 0 values, which
   is causing an error when the array is referenced elsewhere.
 * This can easily be verified by doing a var_dump() of any of the involved arrays.
   I admit this can all be appropriate and I misunderstand the intent, but it’s 
   the only thing I see unusual. But I’ve been know to miss some obvious errors…
 *  Thread Starter [Timothy Jacobs](https://wordpress.org/support/users/timothyblynjacobs/)
 * (@timothyblynjacobs)
 * [13 years, 1 month ago](https://wordpress.org/support/topic/headers-and-saving-post-data/#post-3705179)
 * Thanks bcworkz,
 * I should probably elaborate slightly. I have a list of checkboxes which correspond
   to the name of a testimonial, the id of the input is the id of post that the 
   testimonial corresponds to. So I am looping through the testimonials to get a
   list of those ids — this list could obviously be stored as an option and refresh
   on the creation or deletion of a post, but for now I’d like to just get this 
   part working 🙂 — and then checking the $_POST variable for each id, recording
   the value and then updating it.
 * It is important to note that the values do save, i.e., everything is sent to 
   the database correctly, and everything works just fine in that regard. WP just
   throws me this error in-between.
 * Here is the dump of $testimonials_display
 *     ```
       array(9) { [2854]=> string(2) "on" [2851]=> string(2) "on" [2844]=> int(0) [2839]=> int(0) [2508]=> int(0) [2503]=> int(0) [2501]=> int(0) [2496]=> int(0) [2495]=> int(0) }
       ```
   
 * It looks correct to me and it functions properly.
 * Thanks for the help!
 *  Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * (@bcworkz)
 * [13 years, 1 month ago](https://wordpress.org/support/topic/headers-and-saving-post-data/#post-3705205)
 * Thanks to PHP being a loosely typed language, that sort of array will work fine
   most of the time… until it doesn’t. And then its difficult to locate where it
   failed. I still believe this sort of array is confusing some WP function that
   is expecting a more conventional data structure, which through some convoluted
   chain reaction, throws the errors you see.
 * I see two things a bit unorthodox that could be an issue, or I could be completely
   wrong and the problem lies elsewhere. The more likely cause is easy to test. 
   There may be a problem with the mixed data types in the array values, which are
   either a string `"on"` or an integer `0`. Simply assigning the string `"0"` instead
   of the integer `0` could solve the problem. Just ensure whatever is processing
   the data knows how to deal with `"0"` instead of `0`. Being loosely typed, it
   should, but you can’t always be sure.
 * The other possibility is similar, but applies to the array index keys. Such arrays
   are usually associative, as in `$testimonials_display['2584']` (string key) instead
   of indexed, as you currently have in `$testimonials_display[2584]` (integer index).
   You can easily convert an ID integer to a string with `strval()`, but the ramifications
   can run deeper. Or not, being loosely typed.
 * Again, this may not really be the problem, but it is the only thing I see unusual.
   Not wrong mind you, just unusual.
 *  Thread Starter [Timothy Jacobs](https://wordpress.org/support/users/timothyblynjacobs/)
 * (@timothyblynjacobs)
 * [13 years, 1 month ago](https://wordpress.org/support/topic/headers-and-saving-post-data/#post-3705208)
 * The second possibility I think is more likely because of how I fixed my problem.
   After crazy amounts of brainstorming as to what could be going on, I looked back
   at the error that WP threw me, and noticed that it had to do with the post object.
   So my idea was that wordpress might have been seeing all of these post ids and
   it got confused by them. So I just appended “testimonial” to the end of the ID
   and removed “testimonial” when I saved it to the database. This works! But the
   reason it works doesn’t make so much logical sense. So what I actually could 
   have done was convert the ID to a string when I concatenated it with the “testimonial”
   key word.
 * Thanks so much for the help bcworkz!

Viewing 4 replies - 1 through 4 (of 4 total)

The topic ‘Headers and Saving Post Data’ is closed to new replies.

## Tags

 * [headers](https://wordpress.org/support/topic-tag/headers/)
 * [metaboxes](https://wordpress.org/support/topic-tag/metaboxes/)
 * [save](https://wordpress.org/support/topic-tag/save/)

 * In: [Hacks](https://wordpress.org/support/forum/plugins-and-hacks/hacks/)
 * 4 replies
 * 2 participants
 * Last reply from: [Timothy Jacobs](https://wordpress.org/support/users/timothyblynjacobs/)
 * Last activity: [13 years, 1 month ago](https://wordpress.org/support/topic/headers-and-saving-post-data/#post-3705208)
 * Status: not resolved

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