Add additonal field to Master Study Account Edit Page

<?php

To review the saving process: masterstudy-lms-learning-management-system/lms/classes/user.php, function save_user_info

1) Aggiungere tramite filtro i valori che lo script cerca e il loro relativo valore
add_filter( 'stm_lms_current_user_data', 'current_user_data' );
function current_user_data($current_user_data) {
    $current_user_data['billing_vat_number'] = get_user_meta(get_current_user_id(), 'billing_vat_number');
    $current_user_data['billing_tax_code'] = get_user_meta(get_current_user_id(), 'billing_tax_code');
    return $current_user_data;
}

2) Aggiungere le chiavi dei campi abilitati al salvataggio. Tutti i campi vegnono salvati nella tabella usermeta
add_filter( 'stm_lms_extra_user_fields', 'additional_fields' );
public function additional_fields($additional_fields) {
    $additional_fields['billing_vat_number'] = [
        'label' => esc_html__( 'VAT Number', 'sedweb-masterstudy-addon' ),
    ];

    $additional_fields['billing_tax_code'] = [
        'label' => esc_html__( 'Tax Number', 'sedweb-masterstudy-addon' ),
        'required' => true
    ];
    return $additional_fields;
}

3) Override del template stm-lms-templates/account/private/edit_account/name.php . NB i nome dei campi specificati nel v-model devono essere gli stessi indicati al punto 1. 
Attenzione: lasciare data.meta prima di specificare il nome del nuovo campo.

<div class="col-md-6">
    <div class="form-group form-group-social">
        <label class="heading_font"><?php esc_html_e( 'VAT Number', 'masterstudy-lms-learning-management-system' ); ?></label>
        <input v-model="data.meta.billing_vat_number"
               class="form-control"
               placeholder="<?php esc_html_e( 'VAT Number', 'masterstudy-lms-learning-management-system' ) ?>"/>
    </div>
</div>
<div class="col-md-6">
    <div class="form-group form-group-social">
        <label class="heading_font"><?php esc_html_e( 'Tax Code', 'sedweb-masterstudy-addon' ); ?></label>
        <input v-model="data.meta.billing_tax_code"
               class="form-control"
               placeholder="<?php esc_html_e( 'Tax Code', 'sedweb-masterstudy-addon' ) ?>"/>
    </div>
</div>