Question

I’ve got a Relationships class and i’d like to spit out a list of how many friends a user had on a specific date range (between today and 4 weeks ago).

I’ve tried the following in an html.erb but it doesn’t appear to be working:

<table>
<% rightnow = DateTime.now.to_i %>
<% twentyeight = Time.at(rightnow).to_time - 28.days %>
<% twght = twentyeight.to_i %>
<% (twght..rightnow).step(1.day).map do |time| %>
  <tr><th><%= Time.at(time).strftime("%a %b %y") %></th></tr>
  <tr><td><%= Relationship.where(:follower_id => @user.id, :created_at => from .. to time ).count %></td></tr>
</table>

I suspect the answer might be along the lines of this one but i don’t know how to implement it… Ruby count items by date

Also, as i’m still grappling with MVC, how might i clean up the code? I tried creating a method in my users_controller but was unable to succesfully call it.

Cheers.

Edit:

Here is another attempt at it, which works. Feedback welcome:

<tfoot>
<% before = DateTime.now - 28.days%>
<% following =  Relationship.where(:followed_id => @user.id) %>
<tr>
<% before.step(before + 28, 1) do |time| %>
<th><%= time.strftime("%a %b #{time.day.ordinalize}") %></th>
<% end %>

<% before.step(before + 28, 1) do |time| %>

<td>
<%= following.all(:conditions => ["created_at < ?", time.end_of_day]).count %>
</td><% end %>
</tr>
</tbody> 
</table>

Answer 1

I’m going to skip the part where we pop the ‘why?’ stack. So let’s say you’re looking at the index view of the Relationships controller, for the sake of argument. Most of that code belongs in the controller, so let’s start with the easy case:

class RelationshipsController < ApplicationController
  before_filter :set_user #whatever you do to load your currently logged in user
  def index
    @relationships = @user.relationships.where(:created_at => 28.days.ago..Date.today)
  end
end

in your view:

<table>
  <tr><th><%= Time.at(time).strftime("%a %b %y") %></th></tr>
  <tr><td><%= @relationships.count %></td></tr>
</table>

This will show how many relationships you created in the last 28 days. This doesn’t get you to your running tally though, so let’s refactor the design a bit by adding a method to your model:

class Relationship < ActiveRecord::Base
  #... skip other stuff
  def self.relationship_count_for_days(start_date, end_date)
    where(:created_at => start_date..end_date).count
  end
end

then your view will become:

<table>
  <% 28.downto(1) do |days_ago| %>
    <tr><th><%= days_ago.days.ago.to_time.strftime("%a %b %y") %></th></tr>
    <tr><td><%= @relationships.relationship_count_for_days(28.days.ago, days_ago.days.ago) %></td></tr>
  <% end
</table>