Condition on join tables - Rails

Question

My models:

class Review < ActiveRecord::Base 
  belongs_to :business

class Business < ActiveRecord::Base
  has_many :reviews
  has_and_belongs_to_many :categories

I want to get the Reviews for businesses under a certain category:

Review.joins(:business => :categories).where(:business => {:categories => [1,2,3,4]})

The resulting query:

SELECT "reviews".* FROM "reviews" INNER JOIN 
"businesses" ON "businesses"."id" = "reviews"."business_id" INNER JOIN 
"businesses_categories" ON "businesses_categories"."business_id" = "businesses"."id" 
INNER JOIN "categories" ON "categories"."id" = "businesses_categories"."category_id" 
WHERE "business"."categories" IN (1, 2, 3, 4)

However, I am getting the following error:

ActiveRecord::StatementInvalid: PG::Error: ERROR:  missing FROM-clause entry 
for table "business"
LINE 1: ...id" = "businesses_categories"."category_id" WHERE "business"...

Answer 1

用这个：

Review.joins(:business => :categories).where( :categories => { :id => [1,2,3,4] } )