Title: Multi-Select Callback
Last modified: December 5, 2016

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# Multi-Select Callback

 *  [lrrm](https://wordpress.org/support/users/lrrm/)
 * (@lrrm)
 * [9 years, 5 months ago](https://wordpress.org/support/topic/multi-select-callback/)
 * Hi there,
 * What I want to do is to populate one multi select field with the selected values
   of another multi select field. I’ve read that I can add a callback function to
   a multi select field in order to populate it’s values. I’m refering to the release
   notes here:
 * > Adds new select/multi-select options to retrieve options from a callback.
   >  In the form builder, edit or add a select/multi-select field and add your 
   > callback function in Choices callback field to get populated.
 * My question: What’s a callback function? Is it just a normal PHP function or 
   some of WP add_filter or add_action or something completely different?
 * Do you have an example how such a callback function can look like?
 * Thanks a lot!
    lrrm

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

 *  [borisv](https://wordpress.org/support/users/borisv/)
 * (@borisv)
 * [9 years, 5 months ago](https://wordpress.org/support/topic/multi-select-callback/#post-8517914)
 * This support board considers your post OFF TOPIC.
 * > My question: What’s a callback function?
 * [http://stackoverflow.com/questions/9596276/how-to-explain-callbacks-in-plain-english-how-are-they-different-from-calling-o/9652434#9652434](http://stackoverflow.com/questions/9596276/how-to-explain-callbacks-in-plain-english-how-are-they-different-from-calling-o/9652434#9652434)
 *  Thread Starter [lrrm](https://wordpress.org/support/users/lrrm/)
 * (@lrrm)
 * [9 years, 5 months ago](https://wordpress.org/support/topic/multi-select-callback/#post-8520699)
 * thanks!

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

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 * 2 replies
 * 2 participants
 * Last reply from: [lrrm](https://wordpress.org/support/users/lrrm/)
 * Last activity: [9 years, 5 months ago](https://wordpress.org/support/topic/multi-select-callback/#post-8520699)
 * Status: not resolved