如何在Rails中计算学科百分比

Question

My problem is about calculating a subjects percentage. I have the EnterMark model. Which contains the section_id. Using that I can get the number of students in a particular section. But the problem comes about when calculating the percentage for each subject (In chart view).

Controller

@mark_percent = EnterMark.where(:school_id => params[:school], :course_id =>  params[:course], :section_id => params[:view])

View

<% @mark_percent.each do |i| %>     
  <% @count = i.students.count %> 
    ['<%= i.subject.subject %>', <%= (i.subject_mark_total) / @count  %>],
<% end %>

But @count not taken for each subject. Please help.

Answer 1

我认为这是您想要的：

per = "#{(i.subject_mark_total.to_f / @count) * 100}%"

Answer 2

So you're trying to find an average for each course, is that right? Like Pierre-Louis Gottfrois said, you should try to not define variables inside the view.

In the Course.rb model you could make something like this:

def avg
  total = self.subject_mark_total.to_f
  students = self.students.count
  # get average of scores and round to two decimal places
  average = total / students
  average.round(2)
end

and in the view call <%= course.avg %>

Apologies if i've misunderstood what you're asking for!