CODEWITHSUNDEEP
mysqlruby-on-railsruby
zasman
zasman

Reputation: 486

Cannot add or update a child row: a foreign key constraint fails - Ruby on Rails

My "child" form contains the following select:

<%= child.select :parent_id, options_for_select(Parent.all.map{ |parent| parent.grandparent.name + " - " + parent.name }, {:include_blank => true}) %>

On the "update" action, I get the following error:

Cannot add or update a child row: a foreign key constraint fails (`database_name`.`childs`, CONSTRAINT `fk_part2_5` FOREIGN KEY (`parent_id`) REFERENCES `parents` (`id`))

Models look like so:

class Child < ApplicationRecord
  belongs_to :parent
end

class Parent < ApplicationRecord
  has_many :childs, :dependent => :delete_all 
end

class GrandParent < ApplicationRecord
  has_many :parents, :dependent => :delete_all
end

Upvotes: 1

Views: 798

Answers (2)

zasman
zasman

Reputation: 486

Figured it out. It was my select form that was wrong. The actual value of the individual select options was not the ID's, so it wasn't able to update the table. Figured it out as so:

<%= child.collection_select(:parent_id, Parent.all, :id, :parent_with_grandparent_name) %>

class Parent < ActiveRecord::Base

  has_many :childs, :dependent => :delete_all 
  belongs_to :grandparent
  def parent_with_grandparent_name
    grandparent.name + " - " + name
  end
end

Upvotes: 1

Ilya Konyukhov
Ilya Konyukhov

Reputation: 2791

In options_for_select call you use an array of option texts, which is incorrect. You need to use an array of pairs [option text, option value]:

<%= child.select :parent_id, options_for_select(Parent.all.map { |parent| ["#{parent.grandparent.name} - #{parent.name}", parent.id] }), { include_blank: true } %>

Upvotes: 0

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