Relationship issues....
pruchai
Rails relationships that is 
I am doing something wrong, and can't figure out what and where.
I have 3 models - Command, Contact, and a joined CommandsContact via has_many through relationship, because commands_contacts table holds an extra column - notification_type, which could be either set to host of service.
Models
contact.rb
This one is a special case, because it has 2 extra "virtual" relationships :host_notification_commands and :service_notification_commands, which gives me an ability to selectively get either host or service commands for a user (contact) like this:
Contact.first.host_notification_commands or
Contact.find(3).service_notification_commands etc.
class Contact < ActiveRecord::Base has_many :commands_contacts, :inverse_of => :contact has_many :commands, :through => :commands_contacts has_many :host_notification_commands, -> { where commands_contacts: { :notification_type => 'host' } }, :through => :commands_contacts, :class_name => 'Command', :source => :command has_many :service_notification_commands, -> { where commands_contacts: { notification_type: 'service' } }, :through => :commands_contacts, :class_name => 'Command', :source => :command accepts_nested_attributes_for :host_notification_commands accepts_nested_attributes_for :service_notification_commands end
command.rb
class Command < ActiveRecord::Base has_many :commands_contacts, :inverse_of => :command has_many :contacts, :through => :commands_contacts accepts_nested_attributes_for :commands_contacts end
commands_contracts.rb
class CommandsContact < ActiveRecord::Base belongs_to :command belongs_to :contact accepts_nested_attributes_for :command accepts_nested_attributes_for :contact end
So far. So good. This works as expected (i think?) as I am able to manually create relationships, as long as i have a contact and a command already.
contact = Contact.first command = Command.find(7) contact.host_notification_commands << command
Aaand after this things start to go down south, because a Controller, strong_parameters and accepts_nested_attributes_for come into play, and this is where I fail.
My assumption is that Rails will be able to handle this for me and establish the relationship, right?
def create contact = Contact.new safe_params contact.save end
Because I use accepts_nested_attributes_for, I have to append _attributes to the names of nested objects, right? So i do a simple re-assignment here and then permit them with strong_parameters.
private def safe_params params[:contact][:host_notification_commands_attributes] = params[:contact][:host_notification_commands] params[:contact][:service_notification_commands_attributes] = params[:contact][:service_notification_commands] params.require(:contact) .permit(:contact_name, :host_notification_commands_attributes => [ :id, :command_name, :command_line, :command_description ], :service_notification_commands_attributes => [ :id, :command_name, :command_line, :command_description ])
As far as I understand, this is all that needs to be done and Rails should handle the rest, right? The problem is that it does not even try to to establish a relationship. It does a SELECT and immediately fails.
When I try to create a new record, it fails with:
ActiveRecord::RecordNotFound (Couldn't find Command with ID=1 for Contact with ID=):
Because it hasn't yet created a user a hasn't established a relationship.
When I try to edit and existing contact and establish a relationship with existing command, it fails with