rails » Refactoring Thoughts

find_in_batches is not working

Mar 172010

Days ago, I came across a situation in which find_in_batches does not work correctly, the sample code is as below:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

#NOT WORKING AS EXPECTED.
namespace :studycenter do
desc 'generate item extra items'
task :update_extra_items => :environment do
puts "starting at #{@time = Time.now}......"
Item.find_in_batches(:conditions => {:content_type => "Scenario"}) do |items|
items.each do |item|
begin
if item.extra_items.blank?
item.related_lessons.each do |extra|
@item = ItemExtraItem.create({:item_id => item.id, :extra_item_id => extra.id})
puts "=============================================#{@item.id}"
end
end
puts "finished item with ID:#{item.id}"
rescue Exception => e
puts "something wrong happened!! item with ID:#{item.id}"
next
end
end
puts "------------------spent #{(Time.now - @time)/60} minutes!"
end
puts "finished at #{Time.now}, totally, spent #{(Time.now - @time)/60} minutes!"
end
end

Then I refactor this task, so I can migrate data which generated day by day.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

#WORKING WELL
namespace :studycenter do
desc 'generate item extra items'
task :update_extra_items => :environment do
puts "starting at #{@time = Time.now}......"
(1..300).each do |n|
items = Item.all(:conditions => ["content_type = 'Scenario' and items.created_at >= ? and items.created_at < ?",("2010-03-13".to_date - n.days), ("2010-03-13".to_date - (n-1).days) ])
items.each do |item|
begin
if item.extra_items.blank?
item.related_lessons.each do |extra|
@item = ItemExtraItem.create({:item_id => item.id, :extra_item_id => extra.id})
puts "=============================================#{@item.id}"
end
end
puts "finished item with ID:#{item.id}"
rescue Exception => e
puts "something wrong happened!! item with ID:#{item.id}"
next
end
end
puts "------------------spent #{(Time.now - @time)/60} minutes!"
end
puts "finished at #{Time.now}, totally, spent #{(Time.now - @time)/60} minutes!"
end
end

Do you know why find_in_batches is not working here?
PS: item.related_lessons is an item array, so the item and its related lesson are all the same class.

Answer: In find_in_batches loop, the specific Class only has a range of its instances(e.g. 1~1000), so item.related_lessons can not find the item(e.g. 1001) out of the range..

Performance Practice On Rails

Tech Notes No Responses »

Mar 142010

Last few days, I’ve been mainly struggling with performance issue which was sent to me on Monday. On Rails side, I didn’t add enough necessary cache before I was told about the performance issue. Then I spent two days to improve it by adding cache every where I missed to do that before.

Some shares and confusions as below:

Shares:
1> A very useful educational website about scaling Rails where there are Scaling Rails Screencast Series produced by Gregg Pollack and supported by New Relic.
2> Fragment cache.
If you add many fragment cache in view, it’s really a pain when you expire your cache, so I found there is a better way to expire your cache: if the cached block involves a model, for example, learner’s sidebar involves “User” model’s change, so I just name the cache with User model’s “updated_at”, so I don’t need to expire this cache, it will be done automatically.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

<% cache("sidebar-profile-avatar-#{current_user.id}-#{current_user.updated_at.to_i}") do -%>
<div class="sbb_title"><%= t :my_profile %></div>
<div class="sbb_content">
<table border="0" cellspacing="0" cellpadding="0" class="profile_table">
<tr>
<td width="100" rowspan="2" align="center" valign="top">
<img src="<%= current_user.avatar_url || "/assets/images/portrait_demo.gif" %>" width="90" height="90" />
</td>
<td width="110" height="24"><%= display_learner([current_user], nil) %></td>
</tr>
<tr>
<td valign="top"><strong><%= t :my_goal %></strong><%= display_oral_score(current_user.try(:study_info).try(:target_score)) %></td>
</tr>
</table>
<% end -%>

3> Memcached. Cache whatever you want:

1
2
3
4
5
6
7
8
9
10
11

def related_lessons
cache_key = "related_lessons_for_item#{self.id}"
return Rails.cache.read(cache_key) unless Rails.cache.read(cache_key).nil?
if content_type == "Scenario"
lessons = unit.extra_items.all(:conditions => {:content_id => content.extra_lessons.map(&:id)})
elsif content_type == "ExtraLesson"
lessons = [content.scenario.try(:item)]
end
Rails.cache.write(cache_key, lessons)
return lessons
end

Confusions:
1> It takes much time to render a partial view. that’s pretty confusing to me. Some logs as below:

1 2	Cached fragment hit: views/sidebar-profile-roadmap-1268271150 (0.9ms) Rendered shared/_sidebar_profile (109.8ms)

It seems like even the cached fragment is found, there still needs much time to render the partial..

2> From the log, I saw every request to “roadmap” index action will do the following stuff first, It’s slow. But what that?

<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#<ActionView::Base:0xb5a0e348>#

Any ideas on my confusions? All the involving clues are warmly welcomed.

Formtastic for Rails

Tech Notes 2 Responses »

Dec 222009

I’ve been working on EQ portal during these days, I wanna share a useful gem which I used, it is called Formtastic. it’s a nice way to create form via formtastic, so the finial form is something like:

1
2
3
4
5
6
7
8
9
10
11

<% semantic_form_for @landing, :url=>admin_landings_path do |form| %>
<p>
<% form.inputs do %>
<%= form.input :title, :label => 'Title' %>
<%= form.input :url_slug, :label => 'Url slug' %>
<%= form.input :meta, :label => 'Meta' %>
<%= form.input :content, :label => 'Content' %>
<% end %>
</p>
<p><%= form.buttons %></p>
<% end %>

Then it will generate HTML like this:

1
2
3
4
5
6
7
8
9
10
11
12

<form action="/admin/landings" class="formtastic landing" id="new_landing" method="post"><div style="margin:0;padding:0;display:inline"><input name="authenticity_token" type="hidden" value="EC9WF1oK80Iq6X4NegSkBfVx5gLiYWvBEd7VeNKWHio=" /></div>
<p>
<fieldset class="inputs"><ol>
<li class="string required" id="landing_title_input"><label for="landing_title">Title<abbr title="required">*</abbr></label><input id="landing_title" maxlength="255" name="landing[title]" size="30" type="text" /></li>
<li class="string required" id="landing_url_slug_input"><label for="landing_url_slug">Url slug<abbr title="required">*</abbr></label><input id="landing_url_slug" maxlength="255" name="landing[url_slug]" size="30" type="text" /></li>
<li class="text required" id="landing_meta_input"><label for="landing_meta">Meta<abbr title="required">*</abbr></label><textarea cols="40" id="landing_meta" name="landing[meta]" rows="20"></textarea></li>
<li class="text required" id="landing_content_input"><label for="landing_content">Content<abbr title="required">*</abbr></label><textarea cols="40" id="landing_content" name="landing[content]" rows="20"></textarea></li>

</ol></fieldset>
</p>
<p><fieldset class="buttons"><ol><li class="commit"><input class="create" id="landing_submit" name="commit" type="submit" value="Create Landing" /></li></ol></fieldset></p>
</form>

Also, it can be configured well in display style(not try yet), as well as working with this validation plugin

There is a more detailed Doc at: http://rdoc.info/rdoc/justinfrench/formtastic/blob/35eadf9a0f3e30101993419c3dd3327fb2fdd0b6/Formtastic/SemanticFormBuilder.html. And samples at: http://asciicasts.com/episodes/184-formtastic-part-1

Enjoy it.

SEO on Rails

Tech Notes No Responses »

Dec 152009

This post is a copy of my work stuff, but I want to archive all the links below, they are all about SEO on Rails application, as well as a useful post about jQuery on Rails.

Finally, we decided to create a Rails App for the EQV2 New Website, so I did several homework for this mission. They are:

1. SEO on Rails.
Several rules/good points for seo according to the following websites:
1> http://www.elctech.com/articles/rails-seo-starter-guide
2> http://www.tonyspencer.com/2007/01/26/seo-for-ruby-on-rails/
3> http://www.seoonrails.com/
4> http://blog.csdn.net/diehuan2008/archive/2009/02/23/3925204.aspx

2. Maybe use JQuery more in EQV2.
1> http://yehudakatz.com/2007/01/31/using-jquery-in-rails-part-i/
2> http://www.slideshare.net/wycats/jquery-presentation-to-rails-developers-110063

3. Cache Views.

MORE IDEAS?

But, first version should be structured well and make sure it’s been done before the “deadline”, so this app will be according to the recommendation but not totally implemented in the best way, in all, it still needs your suggestion.

Rails Application Templates

Tech Notes No Responses »

Dec 112009

When talking about templates in Rails, usually people mean the templates which help to re-use views, but this templates is a feature after Rails 2.3 for generating Rails application easily, so give it a try if you haven’t used it yet.

It’s helpful for me to create Rails application according to similar skeleton, a sample below was written about one year ago, but recently I want to create a new application with the same environment/configuration.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65

#idapted_template.rb
generate :rspec

environment 'config.time_zone = "Beijing"'
environment 'config.i18n.default_locale = :zh'

name = ask("What's app's name?")
file 'config/site_config.yml', <<-CODE
app: #{name}
domain: mydomain
CODE

user = ask("What's db user name?")
pwd = ask("What's db user password?")
file 'config/database.yml', <<-CODE
development:
adapter: mysql
encoding: utf8
database: #{name}_development
user: #{user}
password: #{pwd}
pool: 5
timeout: 5000

test:
adapter: mysql
encoding: utf8
database: #{name}_test
user: #{user}
password: #{pwd}
pool: 5
timeout: 5000

production:
adapter: mysql
encoding: utf8
database: #{name}_production
user: #{user}
password: #{pwd}
pool: 5
timeout: 5000
CODE

rake 'db:create:all'
rake 'db:sessions:create'
rake 'db:migrate'

gem 'idp_helpers'
gem 'idp_core'

run "rm public/index.html"

run "rm -rf tmp log"
run "svn import . http://mydomain.com/svn/projects/applications/#{name} -m 'add new app'"
run "rm -rf *"
run "svn checkout http://mydomain.com/svn/projects/applications/#{name} ."

file 'ignore_list', <<-CODE
log
tmp
nbproject
CODE
run "svn propset svn:ignore -F ignore_list ."
run "rm ignore_list"
run "svn commit -m 'set svn ignore'"

There are several useful commands which help you write powerful templates, you can learn more good examples here. or watch Ryan’s Railscasts about App Templates in Rails 2.3.

Enjoy it.

Older Entries

Suffusion theme by Sayontan Sinha

find_in_batches is not working

Performance Practice On Rails

Formtastic for Rails

SEO on Rails

Rails Application Templates

我的网络

最新文章

最新评论

推荐阅读

豆瓣状态

博文存档

find_in_batches is not working

Performance Practice On Rails

Formtastic for Rails

Sessions and Cookies in Ruby on Rails

SEO on Rails

Rails Application Templates

我的网络

最新文章

最新评论

推荐阅读

豆瓣状态

博文存档