Mailer send nil records - ruby-on-rails

Question

I am running tasks to scrap a website to get some concert dates.
My tasks are finding/updating the concerts (date and city), and record them in the data base. I can find them in my rails console and also they can be displayed in my index and show views.
BTW it seems it doesn't go through the create method in the ConcertController (I tried with binding.pry)
After the task is run, I want to get an email alert if a new record was found. When I receive the email it's not complete:
concert_mailer/new_dates.html.erb
<p>The boys are playing at <%= #concert.city %> on <%= #concert.date %></p>
#returns The boys are playing at on
<p>The boys are playing at <%= #concert.inspect %> </p>
#returns: The boys are playing at <Concert id: 1, date: nil, city: nil, created_at: "2017-12-05 20:32:09", updated_at: "2017-12-05 20:32:09">
In rails console I have the record:
<Concert id: 1, date: "2017-12-08 00:00:00", city: "ECHANGE CULTUREL CAMEROUN (0) | au 18 décembre 20...", created_at: "2017-12-05 20:32:09", updated_at: "2017-12-05 20:32:10">
Btw here are my tasks:
namespace :scrap do
desc "This get MM concerts"
url = "http://mountain-men.fr/concerts/"
doc = Nokogiri::HTML(open(url))
data = doc.search('#dateconcert table')
data = data.css('.jaunec' ).map { |tr| tr.css('td').map(&:text) } + doc.css('.jaunef' ).map { |tr| tr.css('td').map(&:text) }
task :find_concerts => :environment do
data.each do |concert|
c = Concert.create!
c.date = concert[0]
c.city = concert[1]
c.save
end
end
task :update_concerts => :environment do
existing_date = Concert.all.map { |c| [c.date, c.city] }
data.each do |concert|
c = Concert.create!
c.date = concert[0]
c.city = concert[1]
c.save unless existing_date.include?([concert[0], concert[1]])
end
Concert.where(city: nil, date:nil).destroy_all
end
end
concert.rb
class Concert < ApplicationRecord
after_create :send_notification
def send_notification
ConcertMailer.new_dates(self).deliver_now
end
end
concert_mailer.rb
class ConcertMailer < ApplicationMailer
default from: "concert#mountain-men.fr"
def new_dates(concert)
#concert = concert
mail( to: "email#exemple.com",
subject: "The boys are back in town"
)
end
end

Answer 1

Your after_create callback to trigger the email is being called before you update your Concert object with data. Instead of creating a empty object, try adding values to your fields before you save the Concert object.
Something like this:
data.each do |concert|
c = Concert.new
c.date = concert[0]
c.city = concert[1]
c.save
end
Or this :
data.each do |concert|
Concert.create(date: concert[0], city: concert[1])
end
This way you will have values saved before the after_create callback is triggered.