rails validate in model that value is inside array

I have a form where i pass a field named :type and i want to check if it's value is inside an array of allowed types so that no one is allowed to post not-allowed types.

the array looks like

@allowed_types = [
   'type1',
   'type2',
   'type3',
   'type4',
   'type5',
   'type6',
   'type7',
   etc...
]

i have tried using validates_exclusion_of or validates_inclusion_of but it doesn't seem to work