Ruby On Rails : I need some explanations about form
<p>I am creating a RoR application. So i want to create a web form with select drop down type. I found the following code in a project. Here is a form:  </p>

<pre><code>&lt;div class="field"&gt;
  &lt;%= f.label :key_words %&gt;&lt;br&gt;
  &lt;%= f.collection_select(:skill_list, User::all_tags, :name, :name, {},{multiple: true}) %&gt;
&lt;/div&gt;
</code></pre>

<p>I create in User controller class : </p>

<pre><code>class UsersController &lt; ApplicationController
...
 def all_tags
    @tags = Tag.all

  end
end
</code></pre>

<p>Here is database : </p>

<p><a href="https://i.stack.imgur.com/CoGP1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CoGP1.png" alt="enter image description here"></a>
1. I don't understand what is <code>User::all_tags</code> ?  Ok understood
2. I cannot see tags in my select drop down. What is missing ?</p>