Assuming generics is a string array and you want to separate it from the new td ...
- @my_patients_list.each do |patient| %tr %td= patient.name %td= patient.date_of_birth %td= patient.gender %td= patient.brand_name.name - patient.generics.each do |gen| %td= gen.name
Otherwise, if you just want to separate the comma ...
- @my_patients_list.each do |patient| %tr %td= patient.name %td= patient.date_of_birth %td= patient.gender %td= patient.brand_name.name %td= patient.generics.map(&:name).join(',')
Bojan source share