active record query order where first

Question

I am using c9 cloud ruby on rails and my Rails version is 5.0.0.1

I want to compose an ActiveRecord query to select the restaurant with the best rating which has not been visited yesterday. When I applied all where, order and first in the query, it throws an error. However, if I don't use where or order, it works fine.

This works:

restaurant1= Restaurant.order('rating').last!
@suggested_restaurants=restaurant1.name

This gives strange results:

restaurant1=Restaurant.order('rating').where{last_visit<Date.yesterday}
@suggested_restaurants=restaurant1

Results: #<ActiveRecord::QueryMethods::WhereChain:0x000000046af7f8>

This triggered error:

restaurant1=Restaurant.order('rating').where{last_visit<Date.yesterday}.last
@suggested_restaurants=restaurant1

Error: undefined method 'last' for #ActiveRecord::QueryMethods::WhereChain:0x00000004587a10>

I can get around this issue by using find_by_sql but I'd like to know why and how to use where in Rails 5. Thanks a lot!

Answer 1

try this:

restaurants = Restaurant.where('last_visit < ?', Date.yesterday).order({ rating: :asc })

this gives you a collection of restaurants matching your constraints passed in where method, the result of which is chained to order method that orders the collection in ascending order of the values in rating column of restaurants table. use :desc if you want to order in descending order.

Then, you can retrive last object with

restaurant1 = restaurants.last