Question

For me, this is about .reverse vs .order('id DESC')

If I have

history = where(user_id: user).order('id DESC')

I can still perform another query like history.where(person_id: person)

If I have

history = where(user_id: user).reverse

I get: NoMethodError: undefined method 'where' for #<Array:0x000001031a3408>

Is this because these functions differ on the array type they should be used with (associative vs regular arrays)? What are my options?

Answer 1

ActiveRecord query methods (e.g. where, order, joins, etc.) return an ActiveRecord::Relation. This allows you to chain the methods to build a query, and the query is not executed until you use the actual data.

Since reverse is not a query method, it operates on the actual data in Ruby, and thus the query is executed so that Ruby may operate on the data, and it returns an Array. Since now you have only data (in the form of an Array) and not an ActiveRecord::Relation, you cannot call another query method.