Error when combining search scopes - ruby-on-rails

Question

I have a web-service that allows clients to search for articles with query parameters.It works fine if only one parameter is included but fails if I combine search_query and category. This is based on Comfortable_Mexican_Sofa where for_category is found. Even if I remove the order statement i get this error.
error
PG::InvalidColumnReference: ERROR: for SELECT DISTINCT, ORDER BY
expressions must appear in select list LINE 1:
...ms_categories"."label" = 'Company News' ORDER BY pg_search_...
^ : SELECT DISTINCT "comfy_cms_pages".* FROM "comfy_cms_pages" INNER JOIN
"comfy_cms_categorizations" ON
"comfy_cms_categorizations"."categorized_id" = "comfy_cms_pages"."id"
AND "comfy_cms_categorizations"."categorized_type" = $1 INNER JOIN
"comfy_cms_categories" ON "comfy_cms_categories"."id" =
"comfy_cms_categorizations"."category_id" INNER JOIN (SELECT
"comfy_cms_pages"."id" AS pg_search_id,
(ts_rank((to_tsvector('simple',
coalesce("comfy_cms_pages"."content_cache"::text, '')) ||
to_tsvector('simple', coalesce("comfy_cms_pages"."label"::text, ''))),
(to_tsquery('simple', ''' ' || 'austin' || ' ''' || ':')), 0)) AS
rank FROM "comfy_cms_pages" WHERE (((to_tsvector('simple',
coalesce("comfy_cms_pages"."content_cache"::text, '')) ||
to_tsvector('simple', coalesce("comfy_cms_pages"."label"::text, '')))
## (to_tsquery('simple', ''' ' || 'austin' || ' ''' || ':')))))
pg_search_comfy_cms_pages ON "comfy_cms_pages"."id" =
pg_search_comfy_cms_pages.pg_search_id WHERE (layout_id = '1' AND
is_published = 't') AND "comfy_cms_categories"."label" = 'Company
News' ORDER BY pg_search_comfy_cms_pages.rank DESC,
"comfy_cms_pages"."id" ASC, "comfy_cms_pages"."created_at" DESC
app/models/article.rb
class Article < Comfy::Cms::Page
cms_is_categorized
include PgSearch
pg_search_scope :search_by_keywords, against: [:content_cache, :label], using: { tsearch: { any_word: true, prefix: true } }
app/commands/search_articles_command.rb
class SearchArticlesCommand
def initialize(params = {})
#since = params[:since_date]
#keys = params[:search_query]
#category = params[:category]
end
def execute
Article.unscoped do
query = if #since.present?
Article.article.since_date(#since)
else
Article.published_article
end
query = query.for_category(#category) if #category.present?
query = query.search_by_keywords(#keys) if #keys.present?
query.where('').order(created_at: :desc)
end
end
end
comfortable-mexican-sofa/lib/comfortable_mexican_sofa/extensions/is_categorized.rb
module ComfortableMexicanSofa::IsCategorized
def self.included(base)
base.send :extend, ClassMethods
end
module ClassMethods
def cms_is_categorized
include ComfortableMexicanSofa::IsCategorized::InstanceMethods
has_many :categorizations,
:as => :categorized,
:class_name => 'Comfy::Cms::Categorization',
:dependent => :destroy
has_many :categories,
:through => :categorizations,
:class_name => 'Comfy::Cms::Category'
attr_accessor :category_ids
after_save :sync_categories
scope :for_category, lambda { |*categories|
if (categories = [categories].flatten.compact).present?
self.distinct.
joins(:categorizations => :category).
where('comfy_cms_categories.label' => categories)
end
}
end
end
module InstanceMethods
def sync_categories
(self.category_ids || {}).each do |category_id, flag|
case flag.to_i
when 1
if category = Comfy::Cms::Category.find_by_id(category_id)
category.categorizations.create(:categorized => self)
end
when 0
self.categorizations.where(:category_id => category_id).destroy_all
end
end
end
end
end
ActiveRecord::Base.send :include, ComfortableMexicanSofa::IsCategorized
Updated Error
PG::SyntaxError: ERROR: syntax error at or near "."
LINE 4: ...e = 'Class' AND categorized_id = 'comfy_cms_pages'.'id' AND ...
^
: SELECT "comfy_cms_pages".* FROM "comfy_cms_pages" INNER JOIN (SELECT "comfy_cms_pages"."id" AS pg_search_id, (ts_rank((to_tsvector('simple', coalesce("comfy_cms_pages"."content_cache"::text, '')) || to_tsvector('simple', coalesce("comfy_cms_pages"."label"::text, ''))), (to_tsquery('simple', ''' ' || 'austin' || ' ''' || ':*')), 0)) AS rank FROM "comfy_cms_pages" WHERE (((to_tsvector('simple', coalesce("comfy_cms_pages"."content_cache"::text, '')) || to_tsvector('simple', coalesce("comfy_cms_pages"."label"::text, ''))) ## (to_tsquery('simple', ''' ' || 'austin' || ' ''' || ':*'))))) pg_search_comfy_cms_pages ON "comfy_cms_pages"."id" = pg_search_comfy_cms_pages.pg_search_id WHERE "comfy_cms_pages"."layout_id" = $1 AND "comfy_cms_pages"."is_published" = $2 AND (
EXISTS (
SELECT 1 FROM categorizations
WHERE categorized_type = 'Class' AND categorized_id = 'comfy_cms_pages'.'id' AND category_id IN (2)
)) ORDER BY pg_search_comfy_cms_pages.rank DESC, "comfy_cms_pages"."id" ASC
working solution but not a scope and have to be careful of order its being called
def self.for_category(_category)
Comfy::Cms::Categorization.includes(:category).references(:category).select(:categorized).pluck(:categorized_id)
find(ids)
end

Answer 1

I think it's best to override for_category built-in filter of your CMS. Too many joins in that query.
Override for_category like this:
scope :for_category, lambda { |*categories|
if (categories = [categories].flatten.compact).present?
self_ids = "{connection.quote_table_name(self.table_name)}.#{connection.quote_column_name(self.primary_key)}"
self.where(
"EXISTS (" +
Comfy::Cms::Categorization.select('1').
where(categorized_type: self.name).
where('categorized_id' => self_ids).
where(category_id: Comfy::Cms::Category.where(label: categories).pluck(:id)).to_sql +
")"
)
end
}
More on SQL EXISTS usage in Rails you can read in my Rails: SQL EXISTS brief how-to.
More on why you bump into that error you can read in question and answer here.
Specifically, pg_search wants order your results by rank. And for_category wants to select distinct fields of Article only, and doesn't care about search rank. Changing its code to use simple EXISTS instead of complex JOIN query will fix that.

Answer 2

I was able to solve this problem by applying reorder to the result of the pg_search result.
search_command.rb
class SearchArticlesCommand
def initialize(params = {})
#since = params['since_date']
#keys = params['search_query']
#category = params['category']
end
def execute
Article.unscoped do
query = Article.article
query = if #since.present?
query.since_date(#since)
else
query.published
end
query = query.for_category(#category) if #category.present?
query = query.search_by_keywords(#keys).reorder('updated_at DESC') if #keys.present?
query
end
end
end
I also overrode for_category (not required)
article.rb
scope :for_category, (lambda do |category|
published
.joins(:categories)
.group(:id)
.where('comfy_cms_categories.label' => category)
.select('comfy_cms_pages.*')
end)