What improvements can be implemented out, with collection and includes in ruby on rails?

Question

I have a very complex query at a beginner level which I am not able to solve out. It takes my page load to around 6 7 seconds on local machine.

The Query is something like for user

self.groups.collect(&:reports).flatten.paginate

Now I run a loop which is something like :

reports.each do |report|
  report.name

  report.user.name
  report.user.image.attachment.url(:thumb)   #User has_one :image , Image belongs_to :user

  report.questions.each do |question|
    question.name 

    question.answers.each do |answer|
      answer.name
    end
  end

  report.comments.each do |comment|
    comment.name 
    comment.user.name
    comment.user.image.attachment.url(:thumb)   #User has_one :image , Image belongs_to :user
  end

end

It has a lot of nested looping which requires a lot of use of includes but me not able to figure out which way should i proceed. My earlier question was N+1 in rails relations with active records?

------------------EDIT------------------

I am able to do

self.groups.includes(:reports => [:user, :questions]) 

or

self.groups.includes(:reports => [:user => [:image]]) 

but not

 self.groups.includes(:reports => [:user => [:image], :questions]) 

whats wrong with this ??

------------------EDIT------------------

self.groups.includes(:reports => [:questions, :user => [:image]]).collect(&:reports).flatten.paginate(:page => page, :per_page => 6)    

This is what seems to work for me with no extra/less eager loading according to bullet gem( https://github.com/flyerhzm/bullet ) but still it takes some 10 seconds to load up the queries and its like a huge huge load. Any further improvements suggested ??

------------------EDIT------------------

 self.groups.includes(:reports => [:questions, .........]).collect(&:reports).paginate

changed to

self.group_reports.includes(:questions, ....... ).paginate

helped a lot

In User Model defined something like

has_many :reports
has_many :group_reports, :through => :groups, :source => :reports

Answer 1

Try to use hash: self.groups.includes(:reports => [:questions, {:user => :image}])