重构rails3查看activerecord调用

Question

In the below snippet, I'm doing a lot of database manipulation in the view. (The .where, and two each loops). What is the best way to refactor this code out of the view?

In the view: index.html.erb

<%- @lesson.sections.each do |section| -%>
          <%- section_correlations = section.correlations.where(:grade => 4) %>
          <%- unless section_correlations.blank? -%>
              <h3><%= section.full_title %></h3>
                <%- section_correlations.each do |correlation| -%>
                      <%= correlation.description %>
                <%- end -%>
          <%- end -%>
<%- end -%>

Answer 1

in the Section model file you could add the following method

def get_correlation_descriptions(grade)
  correlations.where(:grade => grade).map { |c| c.description }
end

and in your lesson model:

def sections_with_correlation_names(grade)
  section_data = []
  sections.each do |s|
    correlation_names = s.get_correlation_descriptions(grade)
    unless correlation_names.blank?
      section_data << { :name => s.full_title, :correlations => correlation_names } 
    end
  end
  section_data
end

then in your view:

<%- @lesson.sections_with_correlation_names(4).each do |section| -%>
  <h3><%= section[:name] %></h3>
  <%= section[:correlations].join("\n") %>
<%- end -%>