Allow binding goal saving w/o exposures and disallow destruction

app/controllers/concerns/finders.rb

@@ -1,6 +1,13 @@
 module Concerns::Finders
   private
 
+  def find_goal(id = params[:id])
+    @goal = Goal.find(id)
+    @project = @goal.project
+  rescue ActiveRecord::RecordNotFound
+    render_404
+  end
+
   def find_meal
     @meal = Meal.find(params[:id])
     @project = @meal.project

app/controllers/targets_controller.rb

@@ -22,9 +22,9 @@ class TargetsController < ApplicationController
   end
 
   def create
-    goal = @project.goals.binding if params[:goal][:id].blank?
-    goal ||= @project.goals.find_by(id: params[:goal][:id])
-    goal ||= @project.goals.build(goal_params)
+    goal_id = params[:goal][:id]
+    goal = goal_id.present? ? @project.goals.find(goal_id) : @project.goals.new
+    goal.attributes = goal_params unless goal.is_binding?
 
     @targets = goal.targets.build(targets_params[:targets]) do |target|
       target.effective_from = params[:target][:effective_from]
@@ -70,7 +70,7 @@ class TargetsController < ApplicationController
   private
 
   def goal_params
-    params.require(:goal).permit(:id, :name, :description)
+    params.require(:goal).permit(:name, :description)
   end
 
   def targets_params

app/models/goal.rb

@@ -6,7 +6,7 @@ class Goal < ActiveRecord::Base
     class_name: 'Exposure', extend: BodyTracking::TogglableExposures
   has_many :quantities, -> { order "lft" }, through: :target_exposures
 
-  validates :target_exposures, presence: true
+  validates :target_exposures, presence: true, unless: :is_binding?
   validates :is_binding, uniqueness: {scope: :project_id}, if: :is_binding?
   validates :name, presence: true, uniqueness: {scope: :project_id},
     exclusion: {in: [I18n.t('targets.form.binding_goal')], unless: :is_binding?}
@@ -16,4 +16,7 @@ class Goal < ActiveRecord::Base
       self.is_binding = false if self.is_binding.nil?
     end
   end
+  before_destroy prepend: true do
+    !is_binding?
+  end
 end