Associating a models using foreign keys - mysql

Question

My goal is to have a setup where Users create Grants as funders and then other users are matched with grants as reachers. I've been playing around with a few options for the model set up such as:
class Grant < ActiveRecord::Base
belongs_to :funder, class_name:"User", foreign_key:"funder_id"
has_many :matches
has_many :researchers, class_name: "User", source: :user, through: :matches
class User < ActiveRecord::Base
has_many :matches
has_many :grants, through: :matches
class Match < ActiveRecord::Base
belongs_to :user
belongs_to :grant
Or ——————————————————————
class Grant < ActiveRecord::Base
has_many :funder_matches, :foreign_key => :researcher_id, :class_name => "Match"
has_many :researcher_matches, :foreign_key => :funder_id, :class_name => "Match"
has_many :researchers, through: :researcher_matches
has_many :funders, through: :funder_matches
class Match < ActiveRecord::Base
belongs_to :grant
belongs_to :user
belongs_to :funder, :class_name => "User"
belongs_to :researcher, :class_name => "User"
class User < ActiveRecord::Base
has_many :matches
has_many :grants, through: :matches
and then in the meantime grants are created by admin by visiting the users profile and passing in the user_id.
In the grant model I have:
def create_grant_with_associations(current_user)
current_user.grants << self
self.funder = current_user
self.save
end
I also have funder_id on the Grants table and in the grant controller I have
def create
#grant = ##user.grants.build(grant_params)
if #grant.save
#grant.create_grant_with_associations(##user)
flash[:info] = "The grant was successfully created"
redirect_to #grant
else
render 'new'
end
end
and then finally I have a collection select to allow admin to select grants and match them with the user.
<h4>Match a grant:</h4>
<%= form_for #user, :html => { :class => 'form-horizontal', :multipart => true } do |f| %>
<div class="field ">
<%= f.label :grants, "Select Grant" %>
<%= f.collection_select(:grant_ids, Grant.all, :id, :name,{:include_blank => 'Show No Grants Matched'}, :multiple => true) %>
</div>
<%= f.submit "Create Match", class: "btn btn-primary"%>
<% end %>
The problem I'm having now is that when i use the collection select it overrides the funder association. Am I on the right track?