Syntax error in spatial query? - ruby-on-rails-3

Question

I wrote a function for found all pois around a track
controller :
def index
#track = Track.friendly.find(params[:track_id])
#tracks = Track.where(way_id: #track.id)
#way = Way.find(1)
#poi_start = Poi.find(#way.point_start)
#pois = #track.pois.sleepsAndtowns
#pois = #way.poi_around_track_from(#poi_start, 50000, #pois)
end
way.rb
def poi_around_track_from(poi, dist, pois)
around_sql = <<-SQL
SELECT
ST_DWithin(
ST_LineSubstring(
way.path,
ST_LineLocatePoint(way.path, pta.lonlat::geometry) + #{dist} / ST_Length(way.path::geography),
ST_LineLocatePoint(way.path, pta.lonlat::geometry) + 100000 / ST_Length(way.path::geography)
),
ptb.lonlat,
2000) is true as pois
FROM ways way, pois pta, pois ptb
WHERE way.id = #{self.id}
and pta.id = #{poi.id}
and ptb.id = #{pois.ids}
SQL
Poi.find_by_sql(around_sql).pois
end
This function return :
syntax error at or near "["
LINE 13: and ptb.id = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
What's wrong, how can I fix it ?

Answer 1

Since you are using standard sql to build the query, (not the ActiveRecord), you will have to use the standard IN clues with where
It looks like pois.ids is returning an array, so, you will have to turn it to a string in the format as below
[1,2] #=> (1,2)
Change,
WHERE way.id = #{self.id}
and pta.id = #{poi.id}
and ptb.id = #{pois.ids}
to
WHERE way.id = #{self.id}
and pta.id = #{poi.id}
and ptb.id IN (#{pois.ids.join(',')})

Answer 2

You can change pois.ids as #semeera207 wrote to string or go another way and compare ptb.id to pois.ids as an array.
WHERE way.id = #{self.id}
and pta.id = #{poi.id}
and array[ptb.id] && #{pois.ids}
To make it faster create gin index
Create index on pois using gin((array[id]));