Retrieve duration since sign up

Question

I'm setting up some transactionals emails on my site and I'd like to send one 3 days after a user signed up if he didn't post. Here is what I have:

function set_mail_html_content_type() {
    return 'text/html';
}

add_action( 'user_help_signup', 10 ,2 );
function user_help_signup( $ID, //DURATION SINCE SIGN UP ) {
    if ( //DURATION SINCE SIGN UP > 3days || count_user_posts( $post->post_author ) > 1 )
        return;

    $to      = get_user_by( 'id', $post->post_author )->user_email;
    $subject = 'Need help ?';
    $headers = array('Content-Type: text/html');
    $message = '<h3>Hi {display_name}! </h3> <p>

    You signed up 3 days ago on mysite.com and we wanted to know if we could help you to get started ';

    wp_mail( $to, $subject, $message, 'Content-Type: text/html' ); 
}

However, I can't find any info on how to retrieve the duration since sign up. How can I achieve this?

Answer 1

WordPress doesn't have a "Duration Since Signup" value so you'll need to calculate it by finding the difference between the user registration date and the current date. I suggest getting the user above the conditional:

function set_mail_html_content_type() {
    return 'text/html';
}

add_action( 'user_help_signup', 10 ,2 );
function user_help_signup( $ID, //DURATION SINCE SIGN UP ) {
    $curr_user  = get_user_by( 'id', $post->post_author );
    $reg_date   = new DateTime( $curr_user->user_registered );
    $curr_date  = new DateTime();
    $days_reg   = intval( $curr_date->diff( $reg_date )->format( "%a" ) );

    if ( $days_reg > 3 || count_user_posts( $post->post_author ) > 1 ) {
        return;
    }

    $to      = $curr_user->user_email;
    $subject = 'Need help ?';
    $headers = array('Content-Type: text/html');
    $message = '<h3>Hi {display_name}! </h3> <p>

    You signed up 3 days ago on mysite.com and we wanted to know if we could help you to get started ';

    wp_mail( $to, $subject, $message, 'Content-Type: text/html' ); 
}

We know that $curr_user->user_registered holds the date that the user registered and DateTime() will get the current date so we can use the built-in DateTime method diff() to get the difference and put it in as day format as %r%a. There's a good StackOverflow Answer on getting the day difference between two dates.

Answer 2

Grab a user object for $ID and do some date math (Almost, but not quite, the same answer as Howdy's):

function user_help_signup( $ID ) {
  $user = get_user_by('id',$ID);
  $user_reg = new DateTime($user->data->user_registered);
  $now = new DateTime();
  $diff = $user_reg->diff($now);

  if ( $diff->days > 3 || count_user_posts( $post->post_author ) > 1 ) {
      return;
  }
  //... your code
}