title: Laravel Notification how to set custom column value
body: <p>I used the <code>php artisan notification:table</code> command to create a custom column named <code>user_id</code> in my notifications migration. How can I set the value of a custom column <code>user_id</code>? </p>
  
  <pre class="lang-php prettyprint-override"><code>Schema::create('notifications', function (Blueprint $table) {
      $table-&gt;uuid('id')-&gt;primary();
      $table-&gt;unsignedBigInteger('user_id');
      $table-&gt;string('type');
      $table-&gt;morphs('notifiable', 50);
      $table-&gt;text('data');
      $table-&gt;timestamp('read_at')-&gt;nullable();
      $table-&gt;timestamps();
      $table-&gt;foreign('user_id')-&gt;references('id')-&gt;on('users')-&gt;onDelete('cascade')-&gt;onUpdate("cascade");
  });
  </code></pre>
  
  <p>In this function, I send a notification but the error is thrown. The user_id column does not have a default value</p>
  
  <pre class="lang-php prettyprint-override"><code>public function saveUser($formdata)
  {
      $password = $formdata['password'];
      $securePassword = Hash::make($password);
  
      $user = User::create(array_merge($formdata, ['password' =&gt; $securePassword]));
      $admin = User::where('type', 'admin')-&gt;first();
      $letter = collect([
          'title' =&gt; $user-&gt;name.' New User Registered in your Portal',
      ]);
  
      Notification::send($admin, new DatabaseNotification($letter));
  
      return $user;
  } 
  </code></pre>
  
  <p>Please help me figure out how to set the <code>user_id</code> value.</p>