WP-CRM System Custom Fields and Meta Boxes

wp-crm-system.php

<?php
/* Add a new meta box with your own custom field.
------------------------------------------------*/

// Add a custom meta box to Contact edit pages.
// For more information, see https://developer.wordpress.org/reference/functions/add_meta_box/
function extend_wpcrm_system() {
  add_meta_box( 'wpcrm_custom_meta', __( 'Custom Meta', 'wp-crm-system-extend' ), 'wpcrmCustomMeta',  'wpcrm-contact', 'side', 'low' );
}
add_action( 'wpcrm_system_custom_meta_boxes', 'extend_wpcrm_system' );

// Add content to the new meta box
function wpcrmCustomMeta() {
  global $post;
  $custom_field = get_post_meta( $post->ID, '_wpcrm_test_custom_field', true ); ?>
  <label for="_wpcrm_test_custom_field"><strong><?php _e('My Custom Field','wp-crm-systemtest-extend'); ?></strong></label><br />
  <input type="number" name="_wpcrm_test_custom_field" value="<?php echo $custom_field; ?>" /><br />
<?php }

// Validate field input and update post_meta table with user's input
function wpcrm_save_test_data( $post_id ) {
  $fields = array( '_wpcrm_test_custom_field' ); // if more than one field is added, add field name to this array
  foreach ( $fields as $field ) {
    if ( array_key_exists( $field, $_POST ) ) {
      $value = $_POST[$field];
      if ( $field == '_wpcrm_test_custom_field' ) {
        $safeinput = preg_replace("/[^0-9\.]/", "", $value); // this field is a number field, so only allow numeric input to be saved
      }
      // if other types of fields (text box, text area, select/radio, etc.) are used you will need to add validation for each type to ensure the correct data type is being saved.
        update_post_meta( $post_id, $field, $safeinput ); // update the post_meta with a valid and validated value
    }
  }
}
add_action( 'save_post_wpcrm-contact', 'wpcrm_save_test_data', 1, 2 );