From: /home/lzap/work/foreman/app/models/nic/base.rb @ line 284 Nic::Base#interface_attribute_uniqueness:

    283: def interface_attribute_uniqueness(attr, base = Nic::Base.where(nil))
 => 284:   require 'pry'; binding.pry
    285:   in_memory_candidates = self.host.present? ? self.host.interfaces.select { |i| i.persisted? && !i.marked_for_destruction? } : [self]
    286:   db_candidates = base.where(attr => self.public_send(attr))
    287:   db_candidates = db_candidates.select { |c| c.id != self.id && in_memory_candidates.map(&:id).include?(c.id) }
    288:   errors.add(attr, :taken) if db_candidates.present?
    289: end

[1] pry(#<Nic::Managed>)> app|I Started GET "/tasks/6b122264-4294-4605-bd2a-b26451b73113" for 127.0.0.1 at 2018-04-09 13:01:08 +0200
[1] pry(#<Nic::Managed>)>
[2] pry(#<Nic::Managed>)> in_memory_candidates = self.host.present? ? self.host.interfaces.select { |i| i.persisted? && !i.marked_for_destruction? } : [self]
=> [#<Nic::Managed:0x0055e3cb167b50
  id: 263,
  mac: "52:54:00:d5:e1:6e",
  ip: "192.168.88.3",
  type: "Nic::Managed",
  name: "lyle-antona.home.lan",
  host_id: 187,
  subnet_id: 3,
  domain_id: 1,
  attrs: {},
  created_at: Mon, 09 Apr 2018 12:47:49 CEST +02:00,
  updated_at: Mon, 09 Apr 2018 12:47:49 CEST +02:00,
  provider: nil,
  username: nil,
  password: nil,
  virtual: false,
  link: true,
  identifier: "",
  tag: "",
  attached_to: "",
  managed: true,
  mode: "balance-rr",
  attached_devices: "",
  bond_options: "",
  primary: true,
  provision: true,
  compute_attributes: {},
  ip6: "",
  subnet6_id: nil>]
[3] pry(#<Nic::Managed>)> db_candidates = base.where(attr => self.public_send(attr))
=> [#<Nic::Managed:0x0055e3d30744c0
  id: 262,
  mac: "52:54:00:d5:e1:6e",
  ip: "192.168.88.2",
  type: "Nic::Managed",
  name: "gail-sielaff.home.lan",
  host_id: 186,
  subnet_id: 3,
  domain_id: 1,
  attrs: {},
  created_at: Mon, 09 Apr 2018 12:47:23 CEST +02:00,
  updated_at: Mon, 09 Apr 2018 12:47:23 CEST +02:00,
  provider: nil,
  username: nil,
  password: nil,
  virtual: false,
  link: true,
  identifier: "",
  tag: "",
  attached_to: "",
  managed: true,
  mode: "balance-rr",
  attached_devices: "",
  bond_options: "",
  primary: true,
  provision: true,
  compute_attributes: {},
  ip6: "",
  subnet6_id: nil>,
 #<Nic::Managed:0x0055e3d300ad68
  id: 263,
  mac: "52:54:00:d5:e1:6e",
  ip: "192.168.88.3",
  type: "Nic::Managed",
  name: "lyle-antona.home.lan",
  host_id: 187,
  subnet_id: 3,
  domain_id: 1,
  attrs: {},
  created_at: Mon, 09 Apr 2018 12:47:49 CEST +02:00,
  updated_at: Mon, 09 Apr 2018 12:47:49 CEST +02:00,
  provider: nil,
  username: nil,
  password: nil,
  virtual: false,
  link: true,
  identifier: "",
  tag: "",
  attached_to: "",
  managed: true,
  mode: "balance-rr",
  attached_devices: "",
  bond_options: "",
  primary: true,
  provision: true,
  compute_attributes: {},
  ip6: "",
  subnet6_id: nil>]
[4] pry(#<Nic::Managed>)> db_candidates = db_candidates.select { |c| c.id != self.id && in_memory_candidates.map(&:id).include?(c.id) }
=> []