Jacob Montgomery

def book_params
  params.require(:book).permit(:title)
end

def author_params
  params.require(:book).permit(authors_attributes: [:id, :name, :_destroy])
end

@book = current_user.books.create(book_params)

author = Author.find_or_create_by(name: "foo") do |author|
  # do stuff if author is new
end

@book.book_authors.create(author_id: author.id)

... by modifying the form template (i.e. adding/removing fields) every existing record should be also modified.

I would like to attach multiple forms to a single record

data => {
  foo => value,
  bar => value
}

data => {
    form_1 => {
      foo => value,
      bar => value,
    },
    form_2 => {
      baz => value
    }
}

I am also not sure JSON string manipulation is the right/most efficient way

# execute a block with a different format (ex: an html partial while in an ajax request)
def with_format(format, &block)
  old_formats = formats
  self.formats = [format]
  block.call
  self.formats = old_formats
  nil
end

def controller_action
  with_format :html do
    @html_content = render_to_string :partial => 'path/to/view', :locals => { /* any locals needed in the view */ }
  end
  render :json => { :html_content => @html_content }
end

def clone
  @project = Project.find(params[:id]).amoeba_dup.save
  render 'new'
end

amoeba do
  enable
  include_association :tasks
  prepend :title => "Copy of "
end

export ENV_VAR_DB_USERNAME='the_username_from_env'
# replace ENV_VAR_DB_USERNAME with whatever the env var is from the database.yml file

# rest of your cron stuff
...

rake bien RAILS_ENV=production

task bien: :environment do
  Bien.cron # I'm assuming this is the model/method you're trying to execute, correct?
end

every 1.day, at: '06:25 pm' do
  rake "bien"
end

#columns: user_id
class Listing < ApplicationRecord
  belongs_to :user, optional: true
  has_one :site
  has_many :association_groups
  has_many :users, through: :association_groups
end

listing = Listing.create
listing_site = listing.build_site.save

def slug_candidates
  if self.user_site?
    [
      user.first_name,
      [user.first_name, user.last_name,],
      [user.first_name, user.last_name, :id]
    ]
  else # listing site
    [
      listing.title
    ]
  end
end

<% unless params[:controller] == "devise/sessions" && params[:action] == "new" %>
  <!-- show the menu -->
<% end %>

class User < ApplicationRecord
  has_one :site
  has_one :listing
  has_many :association_groups
  has_many :listings, through: :association_groups
end

#columns: user_id
class Listing < ApplicationRecord
  belongs_to :user
  has_one :site
  has_many :association_groups
  has_many :users, through: :association_groups
end

#columns: user_id, listing_id
class Site < ApplicationRecord
  has_one :user
  has_one :listing
  has_many :association_groups
  has_many :users, through: :association_groups
end

#columns: listing_id, user_id, site_id
class AssociationGroup < ApplicationRecord
  belongs_to :listing, optional: true
  belongs_to :user, optional: true
  belongs_to :site, optional: true
end



user1 = User.create
user1_site = user1.build_site.save
user1_listing = user1.build_listing.save
user1_association_group = user1.association_groups.build(listing_id: user1.listing.id, site_id: user1.site.id).save


user2 = User.create
user2_site = user2.build_site.save
user2_listing = user2.build_listing.save
user2_association_group = user2.association_groups.build(listing_id: user2.listing.id, site_id: user2.site.id).save

# assign user1 to the listing user2 created
user2.listing.association_groups.build(user_id: user1.id).save
user2.listing.users

# assign user2 to the site user1 created
user1.site.association_groups.build(user_id: user2.id).save
user1.site.users