How To fix 'Adding An element to array rather than replacing it'? - php

Question

I'm trying to write a function where logged in users can add favorite properties and store it as an array in user meta table, but instead of adding multiple values it just stores one value and keeps on replacing it. What am I doing wrong here? I was also unsuccessful to add it manually in the database, how to read the structure?
This is for WordPress
function wms_add_to_usermeta( $post_id )
{
$favorites = $this->wms_get_user_meta();
$favorites[] = $post_id;
$this->wms_update_user_meta( $favorites );
return true;
}
WMS GET USER META Function
function wms_get_user_meta( $user = "" )
{
if( ! empty( $user ) ) {
$userdata = $this->get_user_by( 'login', $user );
$user_id = $userdata->ID;
return get_user_meta( $user_id, $this->favorites_meta_key, true );
}
else {
return get_user_meta( $this->wms_get_user_id(), $this>favorites_meta_key, true );
}
}
Update User Meta
function wms_update_user_meta( $arr )
{
return update_user_meta( $this->wms_get_user_id(), $this->favorites_meta_key, $arr );
}
table data structure a:1:{i:0;i:7;} it keeps on replacing i:7; with 7 being the $post_id

Answer 1

You define $favorites when you call mws_get_user_meta in your class. Then you re-declare $favorites as an array when you add the brackets after it, but that is ignored because it is already an array, or as Alex suggests your array might lose it's format when you do that. Then with the = you push the post_id so it ends up at the end of the array.
So you end up with:
$this->wms_update_user_meta( array('stuff returned from wms_get_user_meta, $post_id);
That would explain why your 7 is always at the end of your data.
I would take a look at the mws_get_user_meta function and make sure you are sending the right arguments. The core requires 3 arguments and I suspect your class' function does as well. Here is the core function:
function update_user_meta( $user_id, $meta_key, $meta_value, $prev_value = '' ) {
return update_metadata( 'user', $user_id, $meta_key, $meta_value, $prev_value );
}
Note that $user_id, $meta_key, $meta_value are all required or it will return false.