ACF Conditional display of a custom taxonomy based according to user (when creating/editing a post) WordPress

pjeaje comments:

what do you mean by this? Do these capabilities need any specific abilities?
Don't worry too much about the user roles and capabilities at the moment. But I need each user/teacher to be assigned the role "teacher" and capability "teacher".

What is the end goal you are trying to achieve?
In the new post/post edit ACF box, only populate the student taxonomy with those students(terms) that have the same school(term) as the user(teacher) creating the post.

Make sure you read the Google doc.

pjeaje comments:

You can now comment on the Google doc

Hugo Gonçalves comments:

I already have read the doc.

I was asking about the end goal, because there could be an easier solution for your problem, specially on the maintenance end. It seems a bit too much, to keep adding the students each time, a teacher publishes a new post.

What i mean is, could one of these fellows be a solution for you?
https://wordpress.org/plugins/coursepress/
https://wordpress.org/plugins/wpschoolpress/
https://wordpress.org/plugins/campus-directory/

Cheers
Hugo

pjeaje comments:

That's not what I'm asking... This is an ACF field populate issue only

pjeaje comments:

I'm going to have 1000's of students (terms) and 100's of teachers (users)
when a teacher creates/edits a post that teacher should only be able to see those students in the list that have the same custom school term as themselves.

pjeaje comments:

It's simply a privacy measure to stop teachers from other schools seeing the names of students not in their school.

Hugo Gonçalves comments:

Hi pjeaje, hope i'm still on time to help you out.

Just one question i have, will the students have access to the backend?
Tip: Since you will be back and forth with multiple users for testing purposes, this mighty come handy: // https://wordpress.org/plugins/user-switching/

Two steps.

First:
On the ACF settings screen, in the Achievement field group, change the Student name field type from taxonomy to radio (we'll be getting the students with code).

Second:
In the functions.php file, add this code:

function acf_field_filtered_students($field) {
$teacher_user_meta_tax_id = get_user_meta(get_current_user_id(), 'schools'); // here we grab the school assigned in the teacher User logged in (returns the ID number of that school/taxonomy term)

// https://codex.wordpress.org/Function_Reference/get_current_screen
$current_screen = get_current_screen(); // here we check the current we are on (we don't want this running in the ACF settings page)
$where_do_you_want_it_to_show = 'page'; // or 'post' or other yuo are aiming for

// Are we in the admin/CMS? And does the current user have an assigned school? And is this a post admin page? if these are all true, then lets continue
if (is_admin() && !empty($teacher_user_meta_tax_id) && $current_screen->id === $where_do_you_want_it_to_show) {

// lets create a temp array to hold only the students we want to show
static $this_student_list = null;
$field['choices'] = array();
if($this_student_list !== null) { return $this_student_list; }
$this_student_list = array();

$student_taxonomy_terms = get_terms( array( // get those pesky students (all of them)!!
'taxonomy' => 'student',
'hide_empty' => false,
) );

if(is_array($student_taxonomy_terms) && (count($student_taxonomy_terms) > 0)) { // do we have any students here? If so proceed
foreach($student_taxonomy_terms as $term) { // iterate each student
$term_meta_school = get_term_meta($term->term_id, 'school'); // get the school that each student has assigned to (returns the ID number of that school/taxonomy term)
if ($term_meta_school[0] === $teacher_user_meta_tax_id[0][0]) { // do the IDs of both teacher User (currently logged in) and each student match?
$this_student_list[$term->term_id] = $term->name; // If so than add that student to our temp list
}
}
}
$field['choices'] = $this_student_list; // assign the temp array of corresponding students to the choices of this field
}
return $field; // et voila
}
// https://www.advancedcustomfields.com/resources/acf-load_field/
add_filter('acf/load_field/name=student_name', 'acf_field_filtered_students');

Let me know how it turned out.

Cheers
Hugo

Hugo Gonçalves comments:

Correction: since you are using this in posts not pages i'll add that as the default:

function acf_field_filtered_students($field) {
$teacher_user_meta_tax_id = get_user_meta(get_current_user_id(), 'schools'); // here we grab the school assigned to the teacher User logged in (returns the ID number of that school/taxonomy term)

// https://codex.wordpress.org/Function_Reference/get_current_screen
$current_screen = get_current_screen(); // here we check the current we are on (we don't want this running in the ACF settings page)
$where_do_you_want_it_to_show = 'post'; // or 'page' or other you are aiming for

// Are we in the admin/CMS? And does the current user have an assigned school? And is this a post admin page? if these are all true, then lets continue
if (is_admin() && !empty($teacher_user_meta_tax_id) && $current_screen->id === $where_do_you_want_it_to_show) {

// lets create a temp array to hold only the students we want to show
static $this_student_list = null;
$field['choices'] = array();
if($this_student_list !== null) { return $this_student_list; }
$this_student_list = array();

$student_taxonomy_terms = get_terms( array( // get those pesky students (all of them)!!
'taxonomy' => 'student',
'hide_empty' => false,
) );

if(is_array($student_taxonomy_terms) && (count($student_taxonomy_terms) > 0)) { // do we have any students here? If so proceed
foreach($student_taxonomy_terms as $term) { // iterate each student
$term_meta_school = get_term_meta($term->term_id, 'school'); // get the school that each student has assigned to (returns the ID number of that school/taxonomy term)
if ($term_meta_school[0] === $teacher_user_meta_tax_id[0][0]) { // do the IDs of both teacher User (currently logged in) and each student match?
$this_student_list[$term->term_id] = $term->name; // If so than add that student to our temp list
}
}
}
$field['choices'] = $this_student_list; // assign the temp array of corresponding students to the choices of this field
}
return $field; // et voila
}
// https://www.advancedcustomfields.com/resources/acf-load_field/
add_filter('acf/load_field/name=student_name', 'acf_field_filtered_students');

pjeaje comments:

Thanks i'll test it out.