Compared with non class/module error

Question

I'm trying to limit the number of albums a user can create by only showing a link to a new album if the number of albums is greater than 3. The error I am getting says 'compared with non class/module'

<% if @albums < 3 %>

     <div class="all-albums" id="position-albums">
        <%= link_to 'New Album', "/albums/new", :style => "text-decoration:none; color:black; font-size: 20px;" %>
        <div class="plus-sign">
            <%= link_to '+', "/albums/new", :style => "text-decoration:none; color:black; font-size:80px; color:#85adad;" %>
        </div>
     </div>

<% end %>

Answer 1

If @albums is an AR collection, you can call size, length or count methods to identify the number of objects within it. For instance:

<% if @albums.size <= 3 %>

Also, you should use <= instead of <, according to your post.

All of these 3 methods differ from each other and you should pick the one you need depending on your situation:

• calling count (without the block) is going to execute a SELECT COUNT(*) query. You should use this method in case it's crucial for you to get the latest calculation result from db instead of using a cached version based on the loaded results or in case you don't actually need the records themselves, just the count calculations.

• calling length is going to execute a SELECT * query and call size method on the resulting collection (without producing any further queries to db). It's preferable in case you are going to use the underlying records anyway.

• calling size on the collection that is not loaded yet is going to execute a SELECT COUNT(*). Otherwise size method is going to be called on the loaded collection (without producing any further queries to db).