Update a WP database table from multiple tables - mysql

Question

I am using the WP Google Maps app. This allows map marker data to be entered on the back-end and displayed on maps on the front-end.
I am trying to adapt this so that an Author can create a post, and the data from the post populates the WP Google Maps table so that it appears on the map. In other words, enabling non-admin users to create map markers with additional fields.
The main information for WP Google Maps is stored in a table called wp_wpgmza. I have tried to write an SQL trigger that updates this table with data from wp_posts and wp_postmeta each time a new post is made but I can't crack it. Something about pulling from the two tables and the structure of wp_postmeta
Any suggestions on another way around this problem?
Thanks D

Answer 1

In WordPress, hooks and filters are often used to accomplish most things like that.
You can easily use the following hooks that call your function before saving/inserting a post:
do_action('save_post', $post_ID, $post);
do_action('wp_insert_post', $post_ID, $post);
Here's a sample usage:
function my_function($post_ID, $post) {
}
add_action('save_post', 'my_function', 2);
Inside my_function you could use $wpdb->insert to enter the data to the table.
function my_function($post_ID, $post) {
global $wpdb;
$table = $wpdb->prefix . 'wpgmza';
$data = array(
'column1' => 'value1',
'column2' => 'value2'
);
$wpdb->insert($table , $data);
}
add_action('save_post', 'my_function', 2);
Alternatively, you can use function_exists() and a function used by the plugin itself to insert to the map table.
function my_function($post_ID, $post) {
if (function_exists('some_google_map_app_function')) {
some_google_map_app_function();
}
}
add_action('save_post', 'my_function', 2);
Note: $post_ID, $post are parameters you can use to take a peak into the post data and/or pass along to that google maps function or insert to the table.
Useful Resources:
https://codex.wordpress.org/Function_Reference/add_action
https://codex.wordpress.org/Plugin_API/Action_Reference/save_post