has_many through create relationship from existing models - ruby-on-rails

Question

I have a marketplace where my users can create plans and their customers can join them. So I have a Plan model and a Customer model. The end goal is to subscribe a customer to a plan so I created a Subscription model and a has_many :through association but I need some help on getting the create working properly. A plan and a customer are already existing by the time the subscription is able to happen so I don't need to worry about creating the plan or customer on subscription#create, I just need to worry about joining the existing ones.
Where I'm at right now is I got the create working on the subscriptions model, but it's not associating to the correct customer. I need a Subscription model created for every customer that I subscribe to the plan and I'm using a multi select tag.
I'm using a has_many :through because a plan has many customers but a customer can also have many plans.
Please let me know if anything is not clear I tried to explain it as clearly and concisely as possible.
Plan Model
class Plan < ActiveRecord::Base
has_many :subscriptions
has_many :customers, through: :subscriptions
end
Customer Model
class Customer < ActiveRecord::Base
has_many :subscriptions
has_many :plans, through: :subscriptions, dependent: :delete_all
end
Subscription Model
class Subscription < ActiveRecord::Base
belongs_to :plan
belongs_to :customer
end
Routes.rb
resources :customers
resources :plans do
resources :subscriptions
end
Subscriptions Controller
class SubscriptionsController < ApplicationController
def new
#user = current_user
#company = #user.company
#plan = Plan.find(params[:plan_id])
#subscription = Subscription.new
end
def create
if #subscription = Subscription.create(plan_id: params[:subscription][:plan_id] )
#subscription.customer_id = params[:subscription][:customer_id]
#subscription.save
flash[:success] = "Successfully Added Customers to Plan"
redirect_to plan_path(params[:subscription][:plan_id])
else
flash[:danger] = "There was a problem adding your customers to this plan"
render :new
end
end
private
def subscription_params
params.require(:subscription).permit(:customer_id, :plan_id, :stripe_subscription_id)
end
end
Form:
<%= form_for [#plan, #subscription] do |f| %>
<%= f.hidden_field :plan_id, value: #plan.id %>
<div class="row">
<div class="col-md-6">
<%= f.select :customer_id, options_from_collection_for_select(#company.customers, 'id', 'customer_name', #plan.customers), {}, multiple: true, style: "width: 50%;" %><br />
</div>
<div class="col-md-12">
<%= f.submit "Add Customer To Plan", class: "btn btn-success pull-right" %>
</div>
</div>
<% end %>
params:
{"utf8"=>"✓",
"authenticity_token"=>"###",
"subscription"=>{"plan_id"=>"5", "customer_id"=>["", "153", "155"]},
"commit"=>"Add Customer To Plan",
"action"=>"create",
"controller"=>"subscriptions",
"plan_id"=>"5"}

Answer 1

params[:subscription][:customer_id] is an array:
"subscription"=>{"plan_id"=>"5", "customer_id"=>["", "153", "155"]},
Are you actually trying to set up a subscription between the plan and each of the customers in this array? If so try calling the update method for #plan object instead, passing these through in params[:plan][:customer_ids] (note the s)
EDIT:
When i said "pass through the ids in params[:plan][:customer_ids]" i was expecting you to do the standard controller behaviour for update, which is something along the lines of
#plan = Plan.find(params[:plan_id])
#plan.update_attributes(params[:plan])
if params = {:plan => {:customer_ids => [1,2,3]}} then the above code will be doing this:
#plan.update_attributes({:customer_ids => [1,2,3]})
which is like saying
#plan.customer_ids = [1,2,3]
#plan.save
When you set up an association, you get lots of methods you can call on the object. One of them is <association>_ids, in this case customer_ids, which is a way of setting the association: when you save, it will make the association between #plan and customers 1,2 & 3.
You were doing this:
#plan.customers << params[:plan][:customer_ids]
which is mixing up the customer records with the ids. If you're going to use push, aka <<, you need to push in customer objects, not ids. Just using customer_ids = is a quicker and simpler way of doing this.