What is the right way to count filled multi value field values in drupal?

Question

I've a term reference multi value field. What is the right way to count filled values which is also portable to D8, D9 etc.

The dsm output shows like this:

Answer 1

$wrapper = entity_metadata_wrapper('entity_type', $entity);
dpm($wrapper->{FIELD_NAME}->count());

Dealing with entity reference field you can get the identifires like this:

dpm($wrapper->{FIELD_NAME}->value(array('identifier' => TRUE)));

Answer 2

Using Entity Metadata Wrapper, you can achieve it this way.

$wrapper = entity_metadata_wrapper('node', $node);
$count = count($wrapper->{FIELD_NAME});

Answer 3

It really depends on the type of field, and on when you are trying to retrieve the values.

During hook_form_alter() for checkboxes, radios, and select fields, the values you are referring to are typically set via the #options property. Example: $form['artist_tags']['und']['#options']. You can wrap that in count() to get the number of values.

During hook_form_validate() or hook_form_submit() or a function called from the $form['#after_build'] property, you will also have access to the number of selected values via $form_state['values']['artist_tags']['und'] (or when $form_state['submitted'] is TRUE, check $form_state['input']['artist_tags']['und']).