Remove order in has_many_aggregate queries

[jonian]

This fixes has_many_aggregate on relations with default scope. In the following example one of the associations has a default scope.

class Collection < ApplicationRecord
  has_many :collection_products
  has_many :products, through: :collection_products

  has_many_aggregate :products, :count, :count, "*"
end

class CollectionProduct < ApplicationRecord
  default_scope { order sort_order: :asc }

  belongs_to :collection
  belongs_to :product
end

The products_count method generates the query and error below:

SELECT COUNT(*) AS "count_all", "collection_products"."collection_id" 
  AS "collection_products_collection_id" FROM "products" 
  INNER JOIN "collection_products" ON "products"."id" = "collection_products"."product_id" 
  WHERE "collection_products"."collection_id" IN (1, 2, 3) 
  GROUP BY "collection_products"."collection_id" 
  ORDER BY "collection_products"."sort_order" ASC

ERROR:  column "collection_products.sort_order" must appear in the GROUP BY clause 
or be used in an aggregate function (PG::GroupingError)

[apalmblad]

This makes sense to me => seems like we'd hit this issue with MySQL with sql_mode containing ONLY_FULL_GROUP_BY, and, as you noted, postgres.

Would it be possible to also get a spec?

[jonian]

Hi @apalmblad, thanks for the quick response. I have added a spec. If it is not enough/correct, please let me know.

[jonian]

Hey, this is still an issue with version 3.1. Are you interested in merging the PR if I resolve the conflicts?