How use MATCH(action) AGAINST(?)

How use MATCH(action) AGAINST(?) in Query Builder Class
i have found only like mode

You can try to use RawSql:

PHP Code:

->where(new RawSql("MATCH(action) AGAINST ('words for search')")); 


Got it how use variable? and prevent sql Inhections?

PHP Code:

->where(new RawSql("MATCH(action) AGAINST ($variable)")); 


In a doc