I plan on making a genotype calculator in the future. I intend for this calculator to eventually be able to compute the following from a pairing: probability of color listing all possibilities, genotype. 

I am wanting to make a dropdown menu/text field combination on a very simple webpage to learn how it works so that I can continue my project and hopefully meet this goal. I have searched and tried to figure this out, but I am pretty lost. Currently in my database I have a table called "colors" with the following schema:

```
id
angora_color
genotype
created_at
updated_at

```

I do not intend for users to be able to add data to this form. I want them to be able to select a color from the dropdown box, and get the genotype in a text field below it.

My code so far is as follows:

```
    class Color < ActiveRecord::Base
  has_one :genotype
end

    class Genotype < ActiveRecord::Base
  has_one :color
end

index.html.erb:
<h2>Placeholder for Genotype List..</h2>

    class PagesController < ApplicationController
  def index
  end
end

```

I appreciate any help.