User Field (Relational), bug when updating field using update_field()

• Justinas

• November 3, 2019 at 3:37 am

ACF PRO version 5.8.6, WP version 5.2.4.

I’ve created field “Speakers”:

• Field type – “User”
• Allow Null? – Yes
• Select multiple values? – Yes
• Return format – User ID

When I’m updating field in admin (two users added), everything works correctly:

– DB value:
a:2:{i:0;s:1:"1";i:1;s:3:"101";}

– field admin HTML:

<input type="hidden" id="acf-field_5ce2cd297ade8-input" name="acf[field_5ce2cd297ade8]"/>
<select
    id="acf-field_5ce2cd297ade8"
    class=""
    name="acf[field_5ce2cd297ade8][]"
    data-ui="1"
    data-ajax="1"
    data-multiple="1"
    data-placeholder="Select"
    data-allow_null="1"
    multiple="multiple"
    size="1"
>
    <option value="1" selected="selected" data-i="0">master (Test Test)</option>
    <option value="101" selected="selected" data-i="1">robot</option>
</select>

– UI shows two users:

BUT, when field is update using update_field(), admin UI shows empty value.

– PHP code:
update_field( 'speakers', array( 1, 101 ), $post_id );

– DB value (same as updating field in admin!):
a:2:{i:0;s:1:"1";i:1;s:3:"101";}

– field admin HTML (same as updating field in admin!):

<input type="hidden" id="acf-field_5ce2cd297ade8-input" name="acf[field_5ce2cd297ade8]"/>
<select
    id="acf-field_5ce2cd297ade8"
    class=""
    name="acf[field_5ce2cd297ade8][]"
    data-ui="1"
    data-ajax="1"
    data-multiple="1"
    data-placeholder="Select"
    data-allow_null="1"
    multiple="multiple"
    size="1"
>
    <option value="1" selected="selected" data-i="0">master (Test Test)</option>
    <option value="101" selected="selected" data-i="1">robot</option>
</select>

– UI empty:

Is it bug, or am I missing something?

• Justinas

• November 3, 2019 at 4:14 am

BTW, in both cases
get_field( 'speakers', $post_id );
returns
Array ( [0] => 1 [1] => 101 )

• John Huebner

• November 9, 2019 at 2:39 am

Are you attempting to update the field for a post that does not have a value previously set using the admin?

If this is the case then you need to use the field key instead of the field name when calling update_field().

• Justinas

• November 9, 2019 at 6:27 am

Yes, I did test with update_field() using field key – same outcome.

• John Huebner

• November 9, 2019 at 6:32 am

I’m actually stumped because I don’t see any reason why it shouldn’t be working.

• jsongerber

• March 24, 2020 at 10:23 am

Hello,
Did you find why this was happening?
I have the exact same issue, in the admin the select seems to work since the option has the selected attribute:

<select id="acf-field_5e78f48412b5e" class="select2-hidden-accessible" name="acf[field_5e78f48412b5e][]" data-ui="1" data-multiple="1" data-placeholder="Choisir" data-allow_null="0" multiple="" size="1" tabindex="-1" aria-hidden="true">
<option value="3" selected="selected" data-i="0">jason.g@….ch</option>
</select>

But the select2 doesn’t work, and when saving again from the admin, it resets the value.

Thank you,
Jason