setting persistent plugin parameters in Joomla 3 - php

Question

I'm developing a Joomla 3.x plugin, and want to be able to change the plugin parameter set in the plugin's manifest file programmatically. I believe I need to use a JRegistry object, but I'm not sure about the syntax.
Here's the issue:
// token A is set in plugin params as defined in plugin's XML manifest
var_dump($this->params->get('token')); // prints token "A" as expected
// do some stuff to get a fresh access token, called token "B"
$tokenB = $function_to_get_fresh_token();
// set the new token
if ($tokenB) $this->params->set('token', $tokenB);
var_dump($this->params->get('apptoken')); // prints token "B" as expected
the problem is that on subsequent page reloads, the token reverts to tokenA rather than what I assumed would be the stored value of tokenB.
How do I store the tokenB value in the plugin's parameters in the database?

Answer 1

This is a working example of how to change plugin params from within the plugin (J! 3.4):
// Load plugin called 'plugin_name'
$table = new JTableExtension(JFactory::getDbo());
$table->load(array('element' => 'plugin_name'));
// Params can be changed like this
$this->params->set('new_param', 'new value'); // if you are doing change from a plugin
$table->set('params', $this->params->toString());
// Save the change
$table->store();
Note: If new params are added by plugin dynamically and the plugin is saved afterwards, these new params gets deleted. So one way to deal with it is to add those params as hidden fields to plugin's config XML.

Answer 2

This is just an outline, but something along these lines
$extensionTable = new JtableExtension();
$pluginId = $extensionTable->find('element', 'my_plugin');
$pluginRow = $extensionTable->load($pluginId);
// Do the jregistry work that is needed
// do some stuff to get a fresh access token, called token "B"
$tokenB = $function_to_get_fresh_token();
// set the new token
if ($tokenB) $this->params->set('token', $tokenB);
// more stuff
$extensionTable->save($pluginRow);

Answer 3

I spent a lot of time googling and reading and found no real answer to this. Oddly enough this doesn't seem to have been provided for in Joomla. So here's what I ended up doing:
1) build a function to get your plugin ID, since it will change from one installation to another
private function getPlgId(){
// stupid hack since there doesn't seem to be another way to get plugin id
$db = JFactory::getDBO();
$sql = 'SELECT `extension_id` FROM `#__extensions` WHERE `element` = "my_plugin" AND `folder` = "my_plugin_folder"'; // check the #__extensions table if you don't know your element / folder
$db->setQuery($sql);
if( !($plg = $db->loadObject()) ){
return false;
} else {
return (int) $plg->extension_id;
}
}
2) use the plugin id to load the table object:
$extension = new JTableExtension($db);
$ext_id = $this->getPlgId();
// get the existing extension data
$extension->load($ext_id);
3) when you're ready to store the value, add it to the params, then store it:
$this->params->set('myvalue', $newvalue);
$extension->bind( array('params' => $this->params->toString()) );
// check and store
if (!$extension->check()) {
$this->setError($extension->getError());
return false;
}
if (!$extension->store()) {
$this->setError($extension->getError());
return false;
}
If anyone knows a better way to do this please let me know!