Question

I have Bands and Codes and Users.

the key/codes will let a user do things with the band. I am on the Band#show action and need to generate a code, and then have that code be related to the user and the band.

so:

Code belongs_to :band, belongs_to :user
Band has_many :codes
User has_many :codes

So now I need to use a form_for (I think) to create a button which when pressed does the following:

check if a user has a code with that band(user can have one code per band)

If not:

• Creates a 6 digit alphanumeric key/code (I know ActiveSupport can do
  it: <%= SecureRandom.hex(3)%> but this needs to be in the model or
  controller)
• Set the correct associations, this code works for this user and this band. I am using Devise so I have access to a current_user method
• and return the user to the Band#show
  action

If the user already has a code for that band, then they are given an error “You already have a code”

I want to eventually make this call with Ajax to keep from reloading the page but for now I am just trying to build the function.

Answer 1

First off, I would create the following route in your routes.rb:

resources :bands do
  post :add_code, :on => :member
end

This will create an additional route looking like this:

add_code_band_path POST   /bands/:id/add_code(.:format)  {:action=>"add_code", :controller=>"bands"}

Then from your views you can use the button_to helper method to send a post request like this:

<%= button_to "Add Code", add_code_band_path(@band), :method => :post %>

When the user clicks on that button then you can handle the rest from the controller action like this:

class BandsController < ApplicationController
  ...

  def add_code
    @band = Band.find(params[:id])
    @code = current_user.codes.find_or_create_by_band_id(@band.id)
    render :action => :show
  end

Lastly, the actual randomized code I would generate from a before_create callback from the Code model itself, like this:

class Code < ActiveRecord::Base
  ...

  before_create :generate_code

private
  def generate_code
    self.code = SecureRandom.hex(3)
  end
end

Then if you think it’s necessary then you could also add other verifications like only showing the Add Code button if there is no Code existing or perhaps add error messages if a user tries to add another code for the same band, but I leave that to you. The button_to helper also supports Ajax by using :remote => true so you can further develop it the way you want.