Updating data from a relation

Hello i got this:

Ex:

Member

  • name
  • phone
  • rel_member_id

rel_members

  • id
  • member_id
  • membership_id

Memberships

  • id
  • name
  • another_data

Now in my edit.rhtml.erb
i got al the stuff…

and this: <%=select ‘rel_members’,‘membership_id’,
@objectWithTheCollect%>

my models are connected really good, but i know that something is wrong
in the way i am trying to update the membership of the member.

some help please