Fix "M" hotkey using stale user from fragment cache

Add a SelfAssignmentsController to resolve the current user at request
time, avoiding the use of an incorrect user id baked into a cached URL.

ref: #2211 originally added the "M" hotkey
ref: https://app.fizzy.do/5986089/cards/3722

app/controllers/cards/self_assignments_controller.rb

@@ -0,0 +1,17 @@
+class Cards::SelfAssignmentsController < ApplicationController
+  include CardScoped
+
+  def create
+    if @card.toggle_assignment(Current.user)
+      respond_to do |format|
+        format.turbo_stream { render "cards/assignments/create" }
+        format.json { head :no_content }
+      end
+    else
+      respond_to do |format|
+        format.turbo_stream { render "cards/assignments/create" }
+        format.json { head :unprocessable_entity }
+      end
+    end
+  end
+end

app/javascript/controllers/card_hotkeys_controller.js

@@ -79,7 +79,7 @@ export default class extends Controller {
     const selection = this.#selectedCard
     if (!selection) return
 
-    const url = selection.card.dataset.cardAssignToMeUrl
+    const url = selection.card.dataset.cardAssignToSelfUrl
     if (url) {
       event.preventDefault()
       await post(url, { responseKind: "turbo-stream" })

app/views/cards/display/_preview.html.erb

@@ -11,9 +11,7 @@
   <% card_data[:card_not_now_url] = card_not_now_path(card) %>
   <% card_data[:card_closure_url] = card_closure_path(card) %>
   <% card_data[:action] = "mouseenter->navigable-list#hoverSelect" %>
-  <% if Current.user %>
-    <% card_data[:card_assign_to_me_url] = card_assignments_path(card, params: { assignee_id: Current.user.id }) %>
-  <% end %>
+  <% card_data[:card_assign_to_self_url] = card_self_assignment_path(card) %>
 <% end %>
 
 <%= card_article_tag card, class: "card", draggable: draggable, data: card_data, tabindex: 0 do %>

config/routes.rb

@@ -87,6 +87,7 @@ Rails.application.routes.draw do
       resource :reading
 
       resources :assignments
+      resource :self_assignment, only: :create
       resources :steps
       resources :taggings
 

test/controllers/cards/self_assignments_controller_test.rb

@@ -0,0 +1,44 @@
+require "test_helper"
+
+class Cards::SelfAssignmentsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in_as :kevin
+  end
+
+  test "create assigns to current user" do
+    card = cards(:layout)
+
+    assert_not card.assigned_to?(users(:kevin))
+
+    post card_self_assignment_path(card), as: :turbo_stream
+    assert_response :success
+    assert_meta_replaced(card)
+    assert card.reload.assigned_to?(users(:kevin))
+  end
+
+  test "create toggles off when already assigned" do
+    card = cards(:logo)
+
+    assert card.assigned_to?(users(:kevin))
+
+    post card_self_assignment_path(card), as: :turbo_stream
+    assert_response :success
+    assert_meta_replaced(card)
+    assert_not card.reload.assigned_to?(users(:kevin))
+  end
+
+  test "create as JSON" do
+    card = cards(:layout)
+
+    assert_not card.assigned_to?(users(:kevin))
+
+    post card_self_assignment_path(card), as: :json
+    assert_response :no_content
+    assert card.reload.assigned_to?(users(:kevin))
+  end
+
+  private
+    def assert_meta_replaced(card)
+      assert_turbo_stream action: :replace, target: dom_id(card, :meta)
+    end
+end