JSON is not nested in rails view

Question

I have a several models in a heirarchy, 1:many at each level. Each class is associated only with the class above it and the one below it, ie:

L1 course, L2 unit, L3 unit layout, L4 layout fields, L5 table fields (not in code, but a sibling of layout fields)

I am trying to build a JSON response of the entire hierarchy.

def show
    @course = Course.find(params[:id])
    respond_to do |format|
      format.html # show.html.erb
      format.json do
        @course = Course.find(params[:id])
        @units = @course.units.all
        @unit_layouts = UnitLayout.where(:unit_id => @units)
        @layout_fields = LayoutField.where(:unit_layout_id => @unit_layouts)
        response = {:course => @course, :units => @units, :unit_layouts => @unit_layouts, :layout_fields => @layout_fields}
        respond_to do |format|
          format.json {render :json => response }
        end
      end
    end
  end

The code is bring back the correct values, but the units, unit_layouts and layout_fields are all nested at the same level under course. I would like them to be nested inside their parent.

This is because you're building them with each collection at the top level. That's what the line response = {:course => @course, :units => @units, :unit_layouts => @unit_layouts, :layout_fields => @layout_fields} does. — user229044
– user229044 ♦, Commented Oct 25, 2012 at 22:56
You also shouldn't be re-finding the course inside your format :json block. You already found it up above, you only need the line @course = Course.find(params[:id]) once. — user229044
– user229044 ♦, Commented Oct 25, 2012 at 23:01

user229044 · Accepted Answer · 2012-10-25 23:03:38Z

1

You need to use to_json with :include to include the associated records.

Here's a stab at it:

@course = Course.find(params[:id])

respond_to do |format|
  format.html # show.html.erb
  format.json do
    render :json => @course.to_json(:include => { :units => { :include => :layouts } })
  end
end

It's probably not 100% correct, because you haven't included all the names of your associations, but I'm assuming that Unit has_many Layouts. To include the deeper nesting, add additional nested :includes.

edited Oct 25, 2012 at 23:03

answered Oct 25, 2012 at 22:58

user229044♦

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1 Comment

port5432 Over a year ago

Hi meagar that was exactly what I was looking for. Thanks very much for your time & multiple posts. It works perfectly.

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