How to use ActiveAdmin on models using has_many through association?

Question

I am using ActiveAdmin gem in my project.

I have 2 models using has_many through association. The database schema looks exactly the same as the example in RailsGuide

Answer 1

It's work for me (with chosen)

permit_params category_ids: []

form do |f|
   inputs 'Shop' do
     input :category_ids, collection: Category.all.collect {|x| [x.name, x.id]}, as: :select, multiple: true, input_html: { class: "chosen-input",  style: "width: 700px;"}
    end
   f.actions
end

Answer 2

For 1)

show do
  panel "Patients" do
    table_for physician.appointments do
      column "name" do |appointment|
        appointment.patient.name
      end
      column :appointment_date
    end
  end
end

For 2)

form do |f|
  f.inputs "Details" do # physician's fields
    f.input :name
  end

  f.has_many :appointments do |app_f|
    app_f.inputs "Appointments" do
      if !app_f.object.nil?
        # show the destroy checkbox only if it is an existing appointment
        # else, there's already dynamic JS to add / remove new appointments
        app_f.input :_destroy, :as => :boolean, :label => "Destroy?"
      end

      app_f.input :patient # it should automatically generate a drop-down select to choose from your existing patients
      app_f.input :appointment_date
    end
  end
end

Answer 3

In answer tomblomfield follow up question in comments:

Try the following in your AA ActiveAdmin.register Model do block:

  controller do
    def scoped_collection
      YourModel.includes(:add_your_includes_here)
    end
  end

This should lazy load all your associations for each index page in a separate query

HTH

Answer 4

If you would like show multiple field in a panel row you can use following view:

show do |phy|
   panel "Details" do
        attributes_table do
          ... # Other fields come here
          row :appointment_dates do
            apps=""
            phy.appointments.all.each do |app|
              apps += app.patient.name + ":" + app.appoinment_date + ", "
            end
            apps.chomp(", ")
          end
        end      
   end
end

To place it in you redit form first put appointment_ids to permitted list:

permit_params: appointment_ids:[]

Add has many relationship to the form

form do |f|
   f.has_many :appointments do |app|
     app.inputs "Appointments" do
       app.input :patients, :as => :select, :label => "Assigned Patients"
       app.input :appointment_date
     end  
   end
end

Should work if there is no coding error.

Answer 5

It should solve the N+1 query problem.

show do
  panel "Patients" do
    patients = physician.patients.includes(:appointments)
    table_for patients do
      column :name
      column :appointment_date { |patient|    patient.appointments.first.appointment_date }
    end
  end
end

Answer 6

@monfresh @tomblomfield you can do

has_many :appointments, ->{ includes(:patients) }, :through => :patients

in the physicians model

...or, I'm not sure if you can use it with formtastic but you could make the scope optional with something like

has_many :appointments :through => :patients do
  def with_patients
    includes(:patients)
  end
end

and appointment.patient wont n+1 anymore