Problems with validates_inclusion_of, acts_as_tree and rspec - ruby-on-rails

Question

I have problems to get rspec running properly to test validates_inclusion_of my migration looks like this:
class CreateCategories < ActiveRecord::Migration
def self.up
create_table :categories do |t|
t.string :name
t.integer :parent_id
t.timestamps
end
end
def self.down
drop_table :categories
end
end
my model looks like this:
class Category < ActiveRecord::Base
acts_as_tree
validates_presence_of :name
validates_uniqueness_of :name
validates_inclusion_of :parent_id, :in => Category.all.map(&:id), :unless => Proc.new { |c| c.parent_id.blank? }
end
my factories:
Factory.define :category do |c|
c.name "Category One"
end
Factory.define :category_2, :class => Category do |c|
c.name "Category Two"
end
my model spec looks like this:
require 'spec_helper'
describe Category do
before(:each) do
#valid_attributes = {
:name => "Category"
}
end
it "should create a new instance given valid attributes" do
Category.create!(#valid_attributes)
end
it "should have a name and it shouldn't be empty" do
c = Category.new :name => nil
c.should be_invalid
c.name = ""
c.should be_invalid
end
it "should not create a duplicate names" do
Category.create!(#valid_attributes)
Category.new(#valid_attributes).should be_invalid
end
it "should not save with invalid parent" do
parent = Factory(:category)
child = Category.new #valid_attributes
child.parent_id = parent.id + 100
child.should be_invalid
end
it "should save with valid parent" do
child = Factory.build(:category_2)
child.parent = Factory(:category)
# FIXME: make it pass, it works on cosole, but I don't know why the test is failing
child.should be_valid
end
end
I get the following error:
'Category should save with valid
parent' FAILED Expected #<Category id:
nil, name: "Category Two", parent_id:
5, created_at: nil, updated_at: nil>
to be valid, but it was not Errors:
Parent is missing
On console everything seems to be fine and work as expected:
c1 = Category.new :name => "Parent Category"
c1.valid? #=> true
c1.save #=> true
c1.id #=> 1
c2 = Category.new :name => "Child Category"
c2.valid? #=> true
c2.parent_id = 100
c2.valid? #=> false
c2.parent_id = 1
c2.valid? #=> true
I'm running rails 2.3.5, rspec 1.3.0 and rspec-rails 1.3.2
Anybody, any idea?

Answer 1

The problem is that you can't put a call to Category.all.map(&:id) inside the called to validates_inclusion_of.
The first indication that this is the case will be apparent when you try to run
rake db:migrate:down VERSION=<n>
rake db:migrate:up VERSOIN=<n>
where <n> is the version number of the migration that creates the Category model.
You will get something like:
in /Users/sseefried/tmp/so)
== CreateCategories: reverting ===============================================
-- drop_table(:categories)
-> 0.0032s
== CreateCategories: reverted (0.0034s) ======================================
(in /Users/sseefried/tmp/so)
rake aborted!
SQLite3::SQLException: no such table: categories: SELECT * FROM "categories"
(See full trace by running task with --trace)
This is because rake tries to load app/models/category.rb before running the migration. Because the Category model does not exist it fails.
Another way to see the problem is to do tail -f log/development.log and then try to open a console with script/console. You will see an SQL query of the form:
SELECT * FROM "categories"
in the output. This corresponds to the call to Category.all.map(:&id). However, once you start typing commands like:
c1 = Category.new, :name => "Category 1"
you will see that the query SELECT * from "categories" does not reappear in the log. The moral of the story is only constants can appear in calls to validations_inclusion_of because the code in there will only be evaluated once..
The only reason your console code worked was because, in a previous console session, you had created a Category object with id=1
You can write a custom validation that does what you want with:
validate :parent_exists
protected
def parent_exists
ids = Category.all.map(&:id)
if !parent_id.blank? && !ids.member?(parent_id)
errors.add(:parent_id, "does not point to a valid parent record")
end
end
Your rspec tests will pass once you have added this code.

Answer 2

Actually, you can defer enumerable calculation by simply putting Category.all.map(&:id) into a proc/lambda.
Writing
validates_inclusion_of :parent_id,
in: proc{ Category.all.map(&:id) },
unless: proc{ |c| c.parent_id.blank? }
will fetch categories' ids at the time of validation, not at the time of class declaration.