Undefined method 'find_by_targetable_id' rails activity

Question

I've created an activity model and I'm trying to have it so that when a user deletes their activity it also deletes the corresponding status. I've been able to do it when deleting the status, it deletes the activity but not sure how to do it in the opposite direction. I tried finding the status by targetable_id but I get:

undefined method `find_by_targetable_id' for #<Class:0x8df4a70>

Parameters:

{"_method"=>"delete",
 "authenticity_token"=>"s2wKOZxCBVarT5uge3AIFNXHepFuvNGM+kU/q+ArOjA=",
 "id"=>"18"}

If you're familiar with the public_activity gem then targetable is the same thing as trackable and in this example, the activity id is 18 and it's corresponding status id is 53

ActivitiesController

class ActivitiesController < ApplicationController

  before_filter :authenticate_member!, only: [:destroy]
  before_filter :find_activity, only: [:destroy]

  def index
    following_ids = current_member.following_members.map(&:id)
    @activities = Activity.where("member_id in (?)", following_ids.push(current_member.id)).order("created_at desc").all
  end

  def destroy
    @status = Activity.targetable 
        if @status      
            @status.destroy
        end
    @activity.destroy

    respond_to do |format|
      format.html { redirect_to :back }
      format.json { head :no_content }
    end
  end

  private

  def find_activity
    @activity = current_member.activities.find(params[:id])
  end 

end

StatusesController

class StatusesController < ApplicationController

  before_filter :authenticate_member!, only: [:new, :create, :edit, :update, :destroy] 
  before_filter :find_member
  before_filter :find_status, only: [:edit, :update, :destroy, :show]

  rescue_from ActiveRecord::RecordNotFound do
    render file: 'public/404', status: 404, formats: [:html]
  end


  # GET /statuses
  # GET /statuses.json
  def index
    @statuses = Status.order('created_at desc').all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @statuses }
    end
  end

  # GET /statuses/1
  # GET /statuses/1.json
  def show

    respond_to do |format|
      format.html # show.html.erb
      format.json { redirect_to profile_path(current_member) }
    end
  end

  # GET /statuses/new
  # GET /statuses/new.json
  def new
    @status = Status.new
    @status.build_document

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @status }
    end
  end

  # GET /statuses/1/edit
  def edit

  end

  # POST /statuses
  # POST /statuses.json
  def create
    @status = current_member.statuses.new(params[:status])

    respond_to do |format|
      if @status.save
        current_member.create_activity(@status, 'created')
        format.html { redirect_to :back }
        format.json 
      else
        format.html { redirect_to profile_path(current_member), alert: 'Post wasn\'t created. Please try again and ensure image attchments are under 10Mbs.'  }
        format.json { render json: @status.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /statuses/1
  # PUT /statuses/1.json
  def update

    if params[:status] && params[:status].has_key?(:user_id)
        params[:status].delete(:user_id) 
    end 
    respond_to do |format|
      if @status.update_attributes(params[:status])
        format.html { redirect_to profile_path(current_member), notice: 'Status was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @status.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /statuses/1
  # DELETE /statuses/1.json
  def destroy
    @activity = Activity.find_by_targetable_id(params[:id])
    if @activity
      @activity.destroy
    end 
    @status.destroy

    respond_to do |format|
      format.html { redirect_to :back }
      format.json { head :no_content }
    end
  end

  private
  def find_member
    @member = Member.find_by_user_name(params[:user_name])
  end 

  def find_status
    @status = current_member.statuses.find(params[:id])
  end 

  def sortable_date
    created_at
  end 

end

Answer 1

Should not this line

@status = Activity.targetable

be

@status = @activity.targetable

?

Second note: it probably will be better to move status destroying to Activity model before_destroy callback.