Unit rebase as a separate action

app/controllers/units_controller.rb

@@ -2,7 +2,7 @@ class UnitsController < ApplicationController
   before_action only: [:new] do
     find_unit if params[:id].present?
   end
-  before_action :find_unit, only: [:edit, :update, :destroy]
+  before_action :find_unit, only: [:edit, :update, :rebase, :destroy]
 
   before_action except: :index do
     raise AccessForbidden unless current_user.at_least(:active)
@@ -30,7 +30,7 @@ class UnitsController < ApplicationController
   end
 
   def update
-    if @unit.update(unit_params)
+    if @unit.update(unit_params.except(:base_id))
       flash.now[:notice] = t(".success")
       run_and_render :index
     else
@@ -38,6 +38,16 @@ class UnitsController < ApplicationController
     end
   end
 
+  def rebase
+    permitted = params.require(:unit).permit(:base_id)
+    if permitted[:base_id].blank? && @unit.multiplier != 1
+      permitted.merge!(multiplier: 1)
+      flash.now[:notice] = t(".multiplier_reset", symbol: @unit.symbol)
+    end
+
+    run_and_render :index if @unit.update(permitted)
+  end
+
   def destroy
     if @unit.destroy
       flash.now[:notice] = t(".success")

app/helpers/application_helper.rb

@@ -56,7 +56,7 @@ module ApplicationHelper
   end
 
   def tabular_fields_for(record_name, record_object = nil, options = {}, &block)
-    flash.now[:alert] = record_name.errors.full_messages unless record_name.errors.empty?
+    render_errors(record_name)
     fields_for(record_name, record_object, **options, &block)
   end
 
@@ -94,6 +94,10 @@ module ApplicationHelper
     image_element_to(:link, name, image, options, html_options)
   end
 
+  def render_errors(record)
+    flash.now[:alert] = record.errors.full_messages unless record.errors.empty?
+  end
+
   def render_flash_messages
     flash.map do |entry, messages|
       Array(messages).map do |message|

app/views/units/index.html.erb

@@ -48,7 +48,8 @@
     event.preventDefault();
 
     var params = new URLSearchParams();
-    params.append("unit[base_id]", event.target.closest("tr").getAttribute("data-drop-id"));
+    var base_id = event.currentTarget.getAttribute("data-drop-id").split("_").pop();
+    params.append("unit[base_id]", base_id);
 
     fetch(event.dataTransfer.getData("text/plain"), {
       body: params,
@@ -57,7 +58,7 @@
         "X-CSRF-Token": document.head.querySelector("meta[name=csrf-token]").content,
         "X-Requested-With": "XMLHttpRequest"
       },
-      method: "PATCH"
+      method: "POST"
     })
     .then(response => response.text())
     .then(html => Turbo.renderStreamMessage(html))

app/views/units/rebase.turbo_stream.erb

@@ -0,0 +1 @@
+<% render_errors @unit %>

config/locales/en.yml

@@ -54,6 +54,8 @@ en:
       success: Created new unit
     update:
       success: Updated unit
+    rebase:
+      multiplier_reset: Multiplier of "%{symbol}" has been reset to 1, due to repositioning
     destroy:
       success: Deleted unit
   users:

config/routes.rb

@@ -2,7 +2,11 @@ Rails.application.routes.draw do
   devise_for :users, path: '', path_names: {registration: 'profile'},
     controllers: {registrations: :registrations}
 
-  resources :units, except: [:show], path_names: {new: '(/:id)/new'}
+  resources :units, except: [:show], path_names: {new: '(/:id)/new'} do
+    member do
+      post :rebase
+    end
+  end
 
   resources :users, only: [:index, :show, :update] do
     member do