ruby on rails - Function draws Error with Postgres Databse but not on Sqlite -

so after shifting code heroku in postgres 1 of functions drawing error.

def index     @tutor = tutor.where(:admin => false)     @tutor_array = []      @tutor_array << @tutor.fees_search(params[:fees_search]) if params[:fees_search].present?     @tutor_array << @tutor.subject_search(params[:subject_search]) if params[:subject_search].present?     @tutor_array << @tutor.lssubject_search(params[:lssubject_search]) if params[:lssubject_search].present?     @tutor_array << @tutor.ussubject_search(params[:ussubject_search]) if params[:ussubject_search].present?     @tutor_array << @tutor.jcsubject_search(params[:jcsubject_search]) if params[:jcsubject_search].present?      @tutor_array.each |tutor|       ids = @tutor.merge(tutor).map(&:id)       @tutor = tutor.where(id: ids)     end     @tutor = @tutor.sort_by { |tutor| tutor.rating.rating }.reverse     @tutor = @tutor.paginate(:page => params[:page], :per_page => 2) end 

the particular line gets highlighted ids = @tutor.merge(tutor).map(&:id)

i have read calls works sqlite , not postgres such doing like ? , such. pretty clueless whats wrong here.

here's error coming

activerecord::statementinvalid in tutorscontroller#index

pg::undefinedfunction: error: operator not exist: integer = character varying line 1: ...m "tutors" inner join "profiles" on "tutors"."id" = "profile... ^ hint: no operator matches given name , argument type(s). might need add explicit type casts. : select "tutors".* "tutors" inner join "profiles" on "tutors"."id" = "profiles"."tutor_id" inner join "profile_ussubjects" on "profiles"."id" = "profile_ussubjects"."profile_id" "tutors"."admin" = $1 , "profile_ussubjects"."ussubject_id" = $2

i don't know search try , resolve since dont know postgres triggering error.

so can point me in right direction.

here's tutor model looks

def self.fees_search(n)     @profile = profile.fees(n)     if @profile.empty?       return tutor.none     else       @profile.map |y|         y.tutor       end     end   end    def self.subject_search(s)     @subject = subject.find_by_name(s)     unless @subject.nil?       @subject.tutors      end   end 

the other subject searches same self.subject_search.

i think 1 of problems have deduced this, in self.subject_search(s) method, testing in rails console, line @subject.tutors drawing error.

in rails console ran subject = subject.find_by_name("english") followed subject.tutors , threw error

activerecord::statementinvalid: pg::undefinedfunction: error:  operator not exist: integer = character varying line 1: ...m "tutors" inner join "profiles" on "tutors"."id" = "profile...                                                              ^ hint:  no operator matches given name , argument type(s). might need add explicit type casts. 

why though? im sorry im quite bad postgres , dont understand whats going on , why worked sqlite3. (i read sqlite3 not strict postgres doesn't make clear me)

def index   @tutors = tutor.where(:admin => false).tap |scope|     keys = [:fees_search, :subject_search, :lssubject_search, :ussubject_search, :jcsubject_search]     keys.each |key|       scope.merge!( tutor.send(key, params[key]) ) if params[key].present?      end   end.paginate(:page => params[:page], :per_page => 2) end 

thats start @ least.

this line pretty problematic:

@tutor = @tutor.sort_by { |tutor| tutor.rating.rating }.reverse 

.sort_by pulls records out of db , sorts them in ruby. should instead doing sub-select fetch aggregate of ratings , using in order clause. (please ask new question if unsure how this. out of scope of original question).