Can you do a before create action on a rails controller - ruby-on-rails

Question

I have a create action but I only want the create action to create IF 2 items in the form that is trying to be created are true. Is that possible to do a if statement before completing the create action or is that making my controller too fat?
I have a form that I want to submit to my db, but based on some of the questions in the form, I want the form to bring up another page (A payment page) BEFORE it puts the form info into the db. Only after the charge is successful will the controller put the info in the db if the charge goes thru.
So I want to know is it DRY or even possible to put logic that will preceed the create action in the controller?
--Additional Information--
So Im still trying to get this right...
In my form controller I have
def intermediary
if #model.who_pays == true
#amount = #model.how_much_to_pay
redirect_to charge_path, :notice => "Please make payment before proceeding"
else
redirect_to model_path #to create object
end
end
and then in my actual form I had
Model.new
but i'm changing it to
<%= form_for [#model, url: [intermediary_path]] do |f| %>
is this logic correct?

Answer 1

Without the extra form, this should be handled in your model with validations:
#app/controllers/your_controller.rb
class YourController < ApplicationController
def new
#model = Model.new
end
def create
#model = Model.new model_params
#model.save
end
end
In your model...
#app/models/model.rb
class Model < ActiveRecord::Base
validate :true_questions, on: :create
private
def true_questions
errors.add(:option1, "Must be true") unless option1
errors.add(:option2, "Must be true") unless option2
end
end
With the form, you'll have several choices:
An "intermediary" action with sessions / cookies
JS / Ajax
As mentioned in the comments, this is a question of "state" -- IE how you're able to keep the data integrity throughout the process.
You should check out how stripe handle this - they send the user to an authentication page (where they receive a token), are redirected back to "confirm" page, from which they're able to proceed.
-
Intermediary
If you have an intermediary action, you'll have to change your flow a little:
#config/routes.rb
resources :controller do
get :intermediary, on: :collection
end
#app/controllers/your_controller.rb
class YourController < ApplicationController
def intermediary
# perform validations in the controller
# set instance or session vars if necessary
# render payment page
end
def create
# returned from payment system - input into DB
end
end
This would work quite well, although it means having custom routes and another action.
-
Ajax
A different approach would be to use either Ajax / JS.
This would be achieved by sending data to your app (probably to your "create" action) with certain switches defined. These would give you the ability to perform the required validations before invoking the payment view.
The payment view would be where the Ajax would come in:
#app/assets/javascripts/application.js
$(document).on("submit", "#____", function(){
$.ajax({
url: "controller",
method: "POST",
data: .......
success: function(data){
// show payment page
}
});
});
#app/controllers/your_controller.rb
class YourController < ApplicationController
def create
if params[:x]
# perform validation
# return payment form
else
# capture payment data
# save to db
end
end
end