generate an array of user login date using update_user_meta();

Question

I have begun to create a function to store last login date of user using time() function. Perfectly works!

Now I want to store in a serialize array a list of all user login date.

Question : Do I have to serialize before sending array, or deserialize array I receive?

Problem : For the first time of user is logged I get well one array with first timestamp. (D.B display)

first log in :
a:1:{i:0;i:1703863394;}
second log in :
a:2:{i:0;a:1:{i:0;i:1703863394;}i:1;i:1703863459;}
third log in :
a:2:{i:0;a:2:{i:0;a:1:{i:0;i:1703863394;}i:1;i:1703863459;}i:1;i:1703865295;}

For the second and all the following my function adds each time an array on top of the current one instead of inserting the value after it (php var_dump())

 **Existing last login :**
    array(1) { [0]=> string(23) "a:1:{i:0;i: 1703863394;}" } 
 **New array of last login :**
    array(2) { [0]=> string(23) "a:1:{i:0;i: 1703863394;}" [1]=> int(1703863459) }

I must get only one array with a list of timestamp with the new one at the end . Currently I get two arrays with more one timestamp stored. It is like my function creating a multidimensional array instead of insert new value at the end of existing array.

My function :

function user_last_login_list( $user_login, $user ) {
    $UserLoginDate = [];
    // If last_login user meta exist
    if(metadata_exists( 'user', $user->ID, 'last_login' )){
        //Get all login date if exist
        $ListLoginDate = get_user_meta($user->ID, 'last_login');
        
            foreach($ListLoginDate as $Timestamp){
                array_push($UserLoginDate,$Timestamp;
            }
        //Add the current day to array of login date 
        array_push($UserLoginDate, time()) ;
    }else{ // If it's the first time user logs on
        $UserLoginDate[] = time() ;
    }
    // I tried to use true/false for previous value to check for the fourth parameter without change
    update_user_meta( $user->ID, 'last_login', $UserLoginDate );
}
add_action( 'wp_login', 'user_last_login_list', 10, 2 );

thanks for your help.

Answer 1

Try this, notice how I set the 3rd value of get_user_meta() to "true"

function user_last_login_list( $user_login, $user ) {
    // If last_login user meta exist
    if(metadata_exists( 'user', $user->ID, 'last_login' )){
        // Get all login dates as a single array
        $UserLoginDate = get_user_meta($user->ID, 'last_login', true);
    } else {
        // Initialize as an empty array if it's the first time user logs on
        $UserLoginDate = [];
    }

    // Add the current day to array of login dates
    $UserLoginDate[] = time();

    // Update user meta with the updated array
    update_user_meta( $user->ID, 'last_login', $UserLoginDate );
}
add_action( 'wp_login', 'user_last_login_list', 10, 2 );