sql - ActiveRecord conditional count -

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in application, i'm trying sort items views within last 10 days. i'm using impressionist gem, creates model called impression , records every view here.

i've managed piece of code:

@items = item.joins("left join impressions on impressions.impressionable_id = items.id , impressions.impressionable_type = 'item'")                    .select("count(distinct(ip_address)) counter, impressionable_id, items.title, items.id, items.image")                    .group('items.id')                    .order("counter desc")                    .page(params[:page])                    .per_page(9)

this sorts items total unique views. however, want count impressions have been made within last 10 days. led me add where method such:

  time_range = (time.now - 10.days)..time.now    @items = item.joins("left join impressions on impressions.impressionable_id = items.id , impressions.impressionable_type = 'item'")    .select("count(distinct(ip_address)) counter, impressionable_id, items.title, items.id, items.image")    .where('impressions.created_at' => time_range)    .group('items.id')    .order("counter desc")    .page(params[:page])    .per_page(9)

however, excludes items has no views, not want. these should represented 0 view.

any suggestions how fix problem?

i had use case, along modifications make run on heroku's postgres server.

  start_date = (time.now - 10.days)   end_date = time.now   joins("left join impressions on impressions.impressionable_id = items.id , impressions.impressionable_type = 'item'")       .select("count(distinct(case when (impressions.created_at between '#{start_date}' , '#{end_date}') ip_address end)) counter, impressionable_id, items.gender, items.title, items.id, items.image")       .group('items.id', 'impressions.impressionable_id')       .order("counter desc")

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