Add custom field to post with some part of url as value

Question

I wish to move my site from some other CMS to WP. There is no any usefull migration, export option in my current CMS so I will need to create posts again manually. I will to transfer important fields of posts on current CMS to custom fields on WP. I am thinking to create some php functions wich will add some custom field to post with some data on new WP site.

Like I said there is no any useful export tool on my current CMS (mostly file system), but I can make on my current CMS post link with some added variable like this:

www.my-site.com/category/subcategory/post-name?value-of-some-field

Then I will crawl my own site to find and make list of links with that suffix "?value-of-some-field". After that I will update links list to new site location on WP test site like this.

www.test-wp.my-site.com/category/subcategory/post-name?value-of-some-field

Then I would like to use code on single.php page to check if url contain "?value-of-some-field" and if it is true to make some custom field with data "value-of-some-fields".

I managed to do this successfully when I know which value I can expect, in case there is several, limited number of different values like this:

<?php
$currenturl = 'http://' . $_SERVER['SERVER_NAME'] . $_SERVER['REQUEST_URI'];

// Look at URL
$pos1 = strpos($currenturl, "?value-one");
$pos2 = strpos($currenturl, "?value-two");
//...

// If URL has "?value-one" create new custom field and add value-one
if($pos1 == true) {
add_post_meta($id, 'my_new_custom_field_name', 'value-one', true);
}
// If URL has "?value-two" create new custom field and add value-two
 elseif($pos2 == true) {
add_post_meta($id, 'my_new_custom_field_name', 'value-two', true);  
}
// ...
?>

What I need is code wich will create new custom field and add data inside it copied from url after "?" sign.

For example if url is like this:

www.site.com/category/subcategory/post-name?some textual description will be here

program will crawl and save that link like this:

www.site.com/category/subcategory/post-name?some%20textual%20description%20will%20be%20here

Of course I can make some START, END markers in url if needed like this

www.site.com/category/subcategory/post-name?START__some%20textual%20description%20will%20be%20here__END

What I need is code which will check if url contains something between "START__" and "__END" and to create new custom field with text between "START__" and "__END", and if it is possible to replace "%20" with space " ".

In this example to create new custom field with value "some textual description will be here"

Answer 1

I found this solution, it works great. I will share it here if someone else need it.

$currenturl = 'http://' . $_SERVER['SERVER_NAME'] . $_SERVER['REQUEST_URI'];
$id = $post->ID;

if ( preg_match('/\?(.+)$/', $currenturl, $matches) ) {
   $value = urldecode($matches[1]);
   add_post_meta($id, 'my_new_custom_field_name', $value, true);
}