Rendering a JSON object of a join-model and its associated models

Question

In a Rails ( 4.1.5 / ruby 2.0.0p481 / win64 ) application I have a many-to-many relationship between Student and Course and a join model StudentCourse

Answer 1

Use JBuilder, it comes by default with Rails. Ignore the lines starting with '#':

Jbuilder.new do |j|

    # courses: [{
    j.courses  do |course|

      # id: 
      j.id course.id 

      # name: 
      j.name course.name

      # students: [{
      j.students  do |student|

          # name: 
          j.name student.name

      end
      # }]

   end
   # }]

end

Not a lot of code. Removing the comments and simplifying some features, it will look like:

student_courses = <...blah...>
json = Jbuilder.new do |j|
  j.courses student_courses do |course|
    j.(course, :id, :name)
    j.students , :name
  end
end.target!

Check out their guide, its pretty awesome to generate JSON in plain Ruby DSL. So go ahead and use whatever ruby code you want to fetch students/courses/studentcourses.