How to apply validation outside form post request

I'm setting up an small application where people can post and publish articles. So visitor can write article and when they save them i do a first small validation with a classic Request class. A this time article is no publied so validation is very small.

But after i want to do a second validation (more complex) when visitor click on 'publish" button. At this time he is not on his form page but on categorie page (Where all posts are listed).

The problem is the button use the GET method and don't send a request with the full post. So i can't use request validation with injection in my controller.

The question is : is there à method for to use request validation without injection ? How can i use a validation rule without sending all post ?

via Chebli Mohamed