Wordpress PHP - How to update plugin setting value in main file - php

Question

This is from inside my Wordpress plugin, inside the main file:
function my_plugin_install() {
$my_site_url = get_site_url();
$my_options['my_site_url'] = $my_site_url;
// Save
}
register_activation_hook(__FILE__, 'my_plugin_install');
Currently, the install is successful but the 'my_site_url' option is not saved. I'm assuming because the way I'm using the $my_options array at this point doesn't mean anything. It should save this data to the wp_options table.
I can't seem to get this to save, or even find a way to test this as using "echo" gives Wordpress an error during install. Is there a best method for running a script and updating the database during install?
Thanks in advance.

Answer 1

You need to use the WordPress function update_option to save your option value:
function my_plugin_install() {
$my_site_url = get_site_url();
update_option('my_site_url', $my_site_url);
}
register_activation_hook(__FILE__, 'my_plugin_install');
And then later, when you need that value, you can use get_option:
$my_site_url = get_option('my_site_url');
*UPDATE
Since it appears you want to manage multiple of your own options, then I suggest using a simple "utility" function, like so:
function update_my_option($key, $value) {
// Load all of the option values from wp_options
$all_options = get_option('my_options');
// Update just the one option you passed in
$all_options[$key] = $value;
// Save to wp_options
update_option('my_options');
}
And, an appropriate getter function:
function get_my_option($key, $default = NULL) {
// Load all of your options from wp_options
$all_options = get_option('my_options');
// Return just the one option you are asking for
return (isset($all_options[$key])) ? $all_options[$key] : $default;
}
Then, rather than calling update_option directly, you'll call this function, as illustrated below:
function my_plugin_install() {
$my_site_url = get_site_url();
update_my_option('my_site_url', $my_site_url);
}
And, to get one of your options:
$my_site_url = get_my_option('my_site_url');