Q:

Geocoder Gem: How to use between two different models?

I'm using the Geocoder and Will Paginate gems to sort my results based on the distance from a user's location and a kids' mom's address. My models are like this:
class User
 has_many :kids
 geocoded_by :address
end

class Kid
  belongs_to :mom
  belongs_to :dad
end

class Mom
  has_many :kids
  has_many :dads, through: :kids
  geocoded_by :address
end

class Dad
  has_many :kids
  has_many :moms, through: :kids
end

Now, I'm trying to use the correct scope that I will use the Users.address and compare it to the Kids.moms.addresses
def show
 @dad = Dad.find(params[:id])
 @user_location = current_user.address
 @kids = @dad.kids.near(@user_location, 100).paginate(page: params[:page], per_page: 25).order(created_at: :desc)
end

This gives me the error:
NoMethodError - undefined method `address' for nil:NilClass:
  app/controllers/dads_controller.rb:14:in `show'
  actionpack (4.0.2) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
  actionpack (4.0.2) lib/abstract_controller/base.rb:189:in `process_action'
  actionpack (4.0.2) lib/action_controller/metal/rendering.rb:10:in `process_action'
.......

Any suggestions?

UPDATE
So far I've done this now:
class ApplicationController
  before_filter :set_user_location

  private

  def set_user_location
    if signed_in?
      @user_location = current_user.address
    end
  end
end

class DadsController

def show
  @dad = Dad.find(params[:id])
  @kids = @dad.kids.joins(:mom).merge(Mom.near(@user_location, 100)).order(name: :asc, created_at: :desc).paginate(page: params[:page], per_page: 25)
end

The code above gets the current users address to work (using Devise) but now I get the error:
ActiveModel::MissingAttributeError

missing attribute: birthday

For all of my Kids attributes on the page.
<% @kids.each do |kid| %>
   <%= kid.birthday %>
   <%= kid.name %>
   <% if kid.upkeep.present? %>
     <%= kid.upkeep %>
     <%= kid.upkeep_size %> 
   <% end %>      
   <%= kid.age %>
   <%= kid.favorite_color %>
<% end %>

I think this is because it thinks Mom has the same attributes as the kid. Any ideas?

A:

This is how you can do it with Geocoder:
def show
  @dad = Dad.find(params[:id])
    near = Mom.near(@user_location, 100, :select => "kids.*")
  @kids = @dad.kids.joins(:mom).merge(near).order(name: :asc, created_at: :desc).page(params[:page])
end

The :select option is what I needed to add.

