Question

In the tasks_controller, I defined:

def index
    @tasks = Task.all

    respond_to do |format|
       format.html # index.html.erb
       format.json { render json: @tasks }
    end
end

I have three parameters in my table: name, task, done.

now, I want to produce:

<table>
    <tr>
        <th>Name</th>
        <th>num of tasks</th>
        <th>num tasks left</th>
    </tr>

    <% @tasks.group_by(&:name).each do |name, tasks| %>
        <tr>
            <td><%= name %></td>
            <td><%= tasks.size %></td>
            <td> here I want to produce the number of tasks left </td>
        </tr>
    <% end %>
</table>

how can I get the number of tasks left? I think it should be something like:

        <% @tasks.group_by(&:name).each do |name, tasks| %>
             <tr>
                <td><%= name %></td>
                <td><%= tasks.size %></td>
                <% @tasks.group_by(name, :done => "yes").each do |name, tasks| %>
                     <td><%= tasks.size %></td>
                <% end %>
             </tr> 
         <% end %>

Answer 1

You had a good idea 😉

<% @tasks.group_by(&:name).each do |name, tasks| %>
  <tr>
    <td><%= name %></td>
    <td><%= tasks.size %></td>
    <td><%= tasks.select{ |task| task.done != 'yes' }.size %></td>
  </tr> 
<% end %>

tasks.select{ |task| task.done != 'yes' } : This will select the tasks where done is not yes, put it in an array and calculate its size (number of tasks not done yet).

I strongly recommend you to set your @tasks variable like following (takes much less performances: the DB does the work for you!)

# in the controller
@tasks = Task.count(:group => 'name') #instead of @tasks = Task.all

It has the same output as @tasks.group_by(...) but is much better in execution time.