I would like to create a Code Auto Action the triggers on joomla_onContentBeforeSave.
The condition that it is a joomla article with catID = 8 has to be correct and the code should check if a certain custom field in the article is filled correct.
If the condition is correct and the field is filled correct the article should be saved, otherwise the article is not possible to save and and alert is given.

Is that possible ? And how would I use the var1_, var2_ etc of the article ?

But how would I get values of custom fields ? They are in $article->custom_field_name
I cannot see how I can get that value from the $article objec ?

Well.. when I create a new article with custom fields with an auto action I use this array:

$article = [
    'catid' => 8,
    'com_fields' => array('cvr' => $cvr, 'adresse' => $address, 'postnr' => $postnr, 'by' => $city, 'telefon' => $telefon, 'webshop-url' => $webshopurl, 'billede' => $imagename , 'beskrivelse' => $description),
    'alias' => '',
    'title' => '[username]',
    'introtext' => '',
    'fulltext' => '',
    'created_by' => $user->id,
    'state' => 1,
    'attribs' => '{"article_layout":"","show_title":"","link_titles":"","show_tags":"","show_intro":"","info_block_position":"","info_block_show_title":"","show_category":"","link_category":"","show_parent_category":"","link_parent_category":"","show_associations":"","show_author":"","link_author":"","show_create_date":"","show_modify_date":"","show_publish_date":"","show_item_navigation":"","show_icons":"","show_print_icon":"","show_email_icon":"","show_vote":"","show_hits":"","show_noauth":"","urls_position":"","alternative_readmore":"","article_page_title":"","show_publishing_options":"","show_article_options":"","show_urls_images_backend":"","show_urls_images_frontend":""}',
   'metadata' => '{"robots":"","author":"","rights":"","xreference":""}',
    'language' => '*'
];

That works just fine.

But I cannot seem to get hold of the com_fields array on an allready created article from another auto action that is triggered by onContentBeforeSave. I need to grap the webshop-url - is that not possible ?