Ruby-on-Rails - Problems displaying a sorted table

Question

I am new to Ruby, and working on code written by someone else. We are having to work with deprecated versions: Ruby 1.8.7, and Rails 2.3.5 - because this is a charity in the developing world and there is no capacity to upgrade.

I have a report which produces a table (a drug inventory), and need to sort it by the drug's name.

The relevant controller code looks like this:

all_drugs = Drug.find(:all,
                      :order => "name ASC")
@stock = {}
all_drugs.each{ |drug|
  drug_id = drug.drug_id
  first_date = Pharmacy.active.find(:first,
                                    :conditions =>["drug_id =?",drug_id],
                                    :order => "encounter_date").encounter_date.to_date rescue nil
  next if first_date.blank?
  next if first_date > @end_date

  start_date = @start_date
  end_date = @end_date

  stock_at = Pharmacy.stock_at(drug_id,end_date)
  if stock_at > 0
    last_activity = "In stock"
    else last_activity = Pharmacy.last_activity(drug_id,end_date)
  end

  drug = Drug.find(drug_id)
  drug_name = drug.name
  @stock[drug_name] = {"dispensed" => 0,"stock_at" => 0,"removed" => 0, "receipts" => 0,"prescribed" => 0,"last_activity" => 0}
  @stock[drug_name]["dispensed"] = Pharmacy.dispensed_drugs_since(drug.id,start_date,end_date)
  @stock[drug_name]["stock_at"] = stock_at
  @stock[drug_name]["removed"] = Pharmacy.total_removed(drug.id,start_date,end_date)
  @stock[drug_name]["receipts"] = Pharmacy.total_delivered(drug.id,start_date,end_date)
  @stock[drug_name]["prescribed"] = Pharmacy.prescribed_drugs_since(drug.id,start_date,end_date)
  @stock[drug_name]["last_activity"] = last_activity
}

The relevant view code looks like this:

<%count = 1
@stock.each{|name,values|
  prescribed = values["prescribed"]
  receipts = values["receipts"]
  dispensed = values["dispensed"]
  removed = values["removed"]
  stock_at = values["stock_at"]
  last_activity = values["last_activity"]
%>

  <tr>
    <td class="color_<%=color%>"><%=name%></td>
    <td class="color_<%=color%> caldata" id="stock_at_<%=count%>"><%=stock_at%></td>
    <td class="color_<%=color%> caldata" id="removed_<%=count%>"><%=removed%></td>
    <td class="color_<%=color%> caldata" id="prescribed_<%=count%>"><%=prescribed%></td>
    <td class="color_<%=color%> caldata" id="dispensed_<%=count%>"><%=dispensed%></td>
    <td class="color_<%=color%> caldata" id="last_activity_<%=count%>"><%=last_activity%></td>
    <td class="color_<%=color%> caldata" id="receipts_<%=count%>"><%=receipts%></td>
  </tr>
  <% count+=1
}%>

This happily produces the correct table but in a random order (re-starting the server and reloading the page will give the table in a new order).

I have tried a variety of options found online. I tried @stock.all.order (doesn't work in Rails 2.x), @stock.find (doesn't accept 2 arguments, :all and :order, and using just :order doesn't help), @stock.sort (no effect), and @stock.sort_by (no effect). All of those placed either at the end of the controller code or just before the @stock.each in the view code.

I have to say I am particularly baffled that the order is random - I would have presumed that even if I was failing to order it by name, the order would still be consistent...

Any help would be very much appreciated!

Yep, thank you, I tried both .sort and .sort_by on @stock - I'll update the question to clarify that. I tried a simple @stock.sort, as well as some variations such as @stock.sort_by { |a| a[0] }, and @stock.sort{|a,b| b[:name] <=> a[:name]}, based on other answers I'd found on this site. None worked, but of course I may have got the syntax wrong. In particular I am not confident that I fully understand the structure and indexing of the @stock array. — Phueal
– Phueal, Commented Jun 1, 2016 at 9:22
@stock is not an array. It is an instance variable, that was declared as a Hash: @stock = {}. You probably want to @stock.sort_by { |k,v| v }, or just @stock.keys.sort.each { |k| } — David K-J
– David K-J, Commented Jun 1, 2016 at 9:57
Thank you for clarifying that for me, I had missed that distinction! Unfortunately neither of these solutions worked. — Phueal
– Phueal, Commented Jun 1, 2016 at 13:33

Community · Accepted Answer · 2017-05-23 11:58:45Z

1

Hashes are unordered by definition in ruby 1.8.7(please check Ruby 1.8: Hash#sort not return hash but array (better way to do this?)) hence we have to use the order as array. There can be no such thing as a sorted Hash. in your view change the line

@stock.each{|name,values|

to

@stock.sort_by {|s, v| s.downcase}.each{|name,values|

edited May 23, 2017 at 11:58

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answered Jun 1, 2016 at 10:26

pshoukry

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14 Comments

Phueal Over a year ago

Thank you, but this made no difference - the list is still unsorted.

pshoukry Over a year ago

can you dump the "@stock" variable and send me the first 3 rows, 'puts @stock'

Phueal Over a year ago

Start of the dump looks like this (dummy data of course): {"Paracetamol (250mg)"=>{"receipts"=>10000.0, "prescribed"=>0, "dispensed"=>0, "last_activity"=>"In stock", "removed"=>0, "stock_at"=>10000.0}, "Paracetamol (1g)"=>{"receipts"=>10000.0, "prescribed"=>0, "dispensed"=>0, "last_activity"=>"In stock", "removed"=>0, "stock_at"=>10000.0}, "EFV (Efavirenz 600mg tablet)"=> N.B. I reloaded the server a couple of times and each time the order of the drugs varies.

pshoukry Over a year ago

Please try Hash[@stock.sort_by {|s, v| s.downcase}].each{|name,values| -- Don't forget to add the v in |s, v|

Patrick De Marta Over a year ago

I suspect that as another hash is being created the issue with unordered hash in ruby 1.8.7 is still generating a 'random' order of drugs in the view.

|

Patrick De Marta · Accepted Answer · 2016-06-01 17:00:37Z

Hash in Ruby 1.8.7 was not ordered, so you can't rely on the order of the keys in @stock.

As a workaround, first I'd query Drug selecting only id and name fields

all_drugs = Drug.find(:all, :select => "id, name")

as you are querying for single drug attributes later in the code.

Then I'd create an empty @stock_keys array to collect drug names, just after the @stock hash definition

@stock = {}
@stock_keys = []

and push drug names in it, right after your query for drug_id

drug = Drug.find(drug_id)
drug_name = drug.name
@stock_keys << drug_name 
@stock[drug_name] = ...

At the end of the iteration on all_drugs, in your controller, I'd sort the @stock_keys array

@stock_keys.sort!

Then, in the view, I'd iterate over the @stock_keys array, retrieving at each step the drug's values from the @stock hash

 @stock_keys.each do |name|
    values = @stock[name] 
    prescribed = values["prescribed"]
    ...
 end

I hope this can help.

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