I've created an K2-item, including an form using the standard plugin method {rsform x}

But now I would like to have :

⦁ the title of the k2-item to be copied into a text form field
⦁ an extrafield of the K2-item to be copied into a (similar type) form field.

If tried several of the suggestions

Easiest solution would be to create a query to grab that information and populate an input with it. You can use the following article as guidance on how to display PHP variables when form is shown:

http://www.rsjoomla.com/support/documentation/view-article/77-display-php-variables-by-default-when-form-is-shown.html

OK, this works fine:

//<code>
$articleid=JRequest::getInt('id'); //gets the items ID from the URL
$db = JFactory::getDBO(); //opens a new database connection
$db->setQuery("SELECT `title` FROM #__k2_items WHERE `id`='$articleid'"); //gets the items title based on its ID
return $db->loadResult();
//</code>

But can you help me with parsing the K2 extrafields. The extrafields are 'coded' JSON style: [{"id":"1","value":"De naam van mijn restaurant"},{"id":"2","value":" This e-mail address is being protected from spambots. You need JavaScript enabled to view it "}]

I tried using json_decode but I can't get it right. E.g.:

//<code>
$articleid=JRequest::getInt('id'); //gets the items ID from the URL
$db = JFactory::getDBO(); //opens a new database connection
$db->setQuery("SELECT `extra_fields` FROM #__k2_items WHERE `id`='$articleid'"); //gets the items extrafields based on its ID
$stuff = $db->loadResult();
$stuffer = json_decode($stuff);
$restmail = $stuffer[2];
return $restmail;
//</code>

Any clue on what I'm doing wrong here?

what exactly are you trying to use? have you tried using

$stuffer->id or $stuffer->value ?

Keep me posted!