sunspot_solr - NoMethodError (undefined method `result=' for nil:NilClass) - ruby-on-rails-3

Question

I have a problem related to the use of sunspot_solr. I have an application that performs some searches using this gem. There are 5 models that has this feature, only 1 of them is showing an error in
#search.results
NoMethodError (undefined method `result=' for nil:NilClass):
app/controllers/financial_dashboards_controller.rb:27:in `index'
Here is my code:
Controller
#search = Sunspot.search(Purchase) do
fulltext params[:search]
with(:product_owner).equal_to(current_user.id)
facet(:status)
if params[:status].present?
with(:status).equal_to(params[:status])
end
facet(:sell_date)
if params[:sell_date].present?
with(:sell_date).equal_to(params[:sell_date])
end
order_by(:sell_date, :desc)
end
#line 27
#sales = #search.results.paginate(:page => params[:page], :per_page => 5)
Model (Purchase):
searchable do
text :product_name
text :product_short_description
integer :product_owner
string :status
string :sell_date
end
def product_name
product.name
end
def product_short_description
product.short_description
end
def product_owner
product.user.id
end
def sell_date
date.to_s(:year_month)
end
#indicates status of the payment and delivery
def status()
if !self.closed.nil?
I18n.t('purchases.status.finished')
elsif !self.measured.nil?
I18n.t('purchases.status.measured')
elsif !self.accomplished.nil?
I18n.t('purchases.status.delivered')
elsif !self.paid.nil?
I18n.t('purchases.status.paid')
elsif !self.canceled.nil?
I18n.t('purchases.status.canceled')
elsif !self.date.nil?
I18n.t('purchases.status.waiting_payment')
end
end
Another strange thing is that on my development machine, this code works perfectly. On production machine that uses nginx, the code displays this error.
I checked the version of gems and they match. I tried
rake sunspot:solr:reindex RAILS_ENV=production
to reindex. I tried
rake sunspot:solr:stop RAILS_ENV=production
rake sunspot:solr:start RAILS_ENV=production
to restart the search server. Even tried to remove solr/ folder and let the start script copy it again.
And why the other models work perfectly? Any ideas how to solve this?
Thanks

Answer 1

In my case, it was a situation when the key field (id) was not unique.
It happened because I have designed a mysql view with non distinct id field.
And that is why sunspot always "dropped" first hit to nil during next non unique row indexation.
So
hit.result = result
raised an error somewhere in sunspot gem code
When i figured it out (i've spent few hours on it), I just have made my id field unique, reindexed my models and problem have gone.