Hook on field change

• Kru-x

• February 24, 2018 at 12:07 pm

Is there a hook that triggers when a field is changed, before saving?

My issue is that I would like to calculate a endtime from a starttime (time/date field). So when a user choose a date and time it will automatically do a calculation on a distance field and speed field and auto-fill the end time.

The calculation is simple but I cant figure out when it gets triggered.

• Beee

• February 25, 2018 at 1:04 am

You can use
https://www.advancedcustomfields.com/resources/acf-pre_save_post/
or
https://www.advancedcustomfields.com/resources/acf-save_post/

• Kru-x

• February 27, 2018 at 6:22 am

Hi Bee,

Thanks for this, still trying to get my head around programming. I should probably have said that I am working in the backend of WP, would this filter work in the backend? And when is this filter triggered?

• Beee

• February 27, 2018 at 7:14 am

Yes it will work in the back-end. Please check the links. It has all the info.

• Kru-x

• March 22, 2018 at 10:26 pm

Nop,

I am not getting it, I can’t get acf/pre_save_post to trigger in the backend at all and read in another post that it wont work on the backend, so confused.

If anyone has an idea how I can calculate a value from two field before I “save Post, ex. I add speed in one field and time in another then it should calculate ETA and autofill a second time field, ps I also have a distance field to do the caclulation.

Any ideas or pointers in the right direction would be appreciated,
Thanks

• Beee

• March 22, 2018 at 10:33 pm

This should give you a nudge in the direction.
This code needs to placed in functions.php.

function acf_57448( $post_id ) {

    $start_date = get_field( 'field_name', $post_id );

    // do stuff to calculate ETA

    update_field( 'eta_field_name', $post_id )

}
add_action( 'acf/save_post', 'acf_57448', 20 );

• Kru-x

• March 23, 2018 at 12:11 am

Hi Bee,

Thanks for your help but you misunderstand (or do I?), I need to fill the eta field out as soon as the ETD and speed is filled out (on field change) before I save the post. Like when you tab to another field it auto fills the other one, as in many computer software, excel is one exemple. hope it make sense!

• Beee

• March 23, 2018 at 1:09 am

Ah ok…. my code gets generated after saving.

What you want is some Javascript, which does something on.change (I think), but that is not my strong point so can’t help you there.

• John Huebner

• March 23, 2018 at 2:11 am

See this documentation https://www.advancedcustomfields.com/resources/adding-custom-javascript-fields/

and this topic that has an example of setting and end date based on a start date https://support.advancedcustomfields.com/forums/topic/autocomplete-end-date-when-start-date-is-selected-in-jquery-date-picker/

It is not exactly what you need, but with a little work it will get you there.

• Kru-x

• May 29, 2018 at 4:20 am

Hi John,

I am terrible sorry for taking such a time to come back and thank you for your answer, has been a busy time. I will look in to it one day as it is still something I want done one day.

Thanks again for your time,

Kru-x