Add toggle button to show/hide subtasks in task list view

app/Formatter/BoardFormatter.php

@@ -58,7 +58,7 @@ class BoardFormatter extends BaseFormatter implements FormatterInterface
             ->findAll();
 
         $task_ids = array_column($tasks, 'id');
-        $tags = $this->taskTagModel->getTagsByTasks($task_ids);
+        $tags = $this->taskTagModel->getTagsByTaskIds($task_ids);
 
         return $this->boardSwimlaneFormatter
             ->withSwimlanes($swimlanes)

app/Formatter/SubtaskListFormatter.php

@@ -16,7 +16,7 @@ class SubtaskListFormatter extends BaseFormatter implements FormatterInterface
      * Apply formatter
      *
      * @access public
-     * @return mixed
+     * @return array
      */
     public function format()
     {

app/Formatter/TaskListFormatter.php

@@ -16,13 +16,13 @@ class TaskListFormatter extends BaseFormatter implements FormatterInterface
      * Apply formatter
      *
      * @access public
-     * @return mixed
+     * @return array
      */
     public function format()
     {
         $tasks = $this->query->findAll();
         $taskIds = array_column($tasks, 'id');
-        $tags = $this->taskTagModel->getTagsByTasks($taskIds);
+        $tags = $this->taskTagModel->getTagsByTaskIds($taskIds);
         array_merge_relation($tasks, $tags, 'tags', 'id');
 
         return $tasks;

app/Formatter/TaskListSubtaskFormatter.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Kanboard\Formatter;
+
+/**
+ * Class TaskListSubtaskFormatter
+ *
+ * @package Kanboard\Formatter
+ * @author  Frederic Guillot
+ */
+class TaskListSubtaskFormatter extends TaskListFormatter
+{
+    /**
+     * Apply formatter
+     *
+     * @access public
+     * @return array
+     */
+    public function format()
+    {
+        $tasks = parent::format();
+        $taskIds = array_column($tasks, 'id');
+        $subtasks = $this->subtaskModel->getAllByTaskIds($taskIds);
+        $subtasks = array_column_index($subtasks, 'task_id');
+        array_merge_relation($tasks, $subtasks, 'subtasks', 'id');
+
+        return $tasks;
+    }
+}