Code snippet that can be used to add more theme suggestions programmatically to fields in drupal 8.
To do that in our custom theme folder in the .theme file we have to add the following hook function: hook_theme_suggestions_HOOK_alter like below:
<?php
/**
* Implements hook_theme_suggestions_field_alter
*/
function mytheme_theme_suggestions_field_alter(array &$suggestions, array $variables) {
// Build a variable with field information
$element = $variables['element'];
// sanitize #view_mode
$sanitized_view_mode = strtr($element['#view_mode'], '.', '_');
// Suggest template
$suggestions[] = 'field__' . $element['#field_type'];
$suggestions[] = 'field__' . $element['#field_name'];
$suggestions[] = 'field__' . $element['#entity_type'] . '__' . $element['#bundle'];
$suggestions[] = 'field__' . $element['#entity_type'] . '__' . $element['#field_name'];
$suggestions[] = 'field__' . $element['#entity_type'] . '__' . $element['#field_name'] . '__' . $element['#bundle'];
$suggestions[] = 'field__' . $element['#entity_type'] . '__' . $element['#field_name'] . '__' . $sanitized_view_mode;
$suggestions[] = 'field__' . $element['#entity_type'] . '__' . $element['#field_name'] . '__' . $element['#bundle'] . '__' . $sanitized_view_mode;
}
