10 Ruby and Rails Pro Tips, for Parisrb meetup.

1. 10 Ruby and Rails Pro Tips
Michel Pigassou, Co-founder & CTO at Fidzup, michel@fidzup.com
2014-08-05
A few things you may or may not know

2. Use debugger
Just use it!
How? http://guides.rubyonrails.org/debugging_rails_applications.html
Bonus:
byebug for Ruby 2: https://github.com/deivid-rodriguez/byebug

3. Inline Assignments
Don't:
params[:routing_data] ? routing_data = params[:routing_data].to_json :
routing_data = {}
Do:
routing_data = params[:routing_data] ? params[:routing_data].to_json : {}

4. Fail Fast
Integer() and Float() raise an Exception
Also Hash#fetch
Bonus: Array()

5. Use Constants and Integers
Example:
CHOICES = [:female, :male, :unknown].freeze
user.sex = CHOICES.index(:female)
user.sex = CHOICES[0]

6. Be Careful with =~
=~ returns an integer or nil
("foo" =~ /foo/) === true #=> false

7. Eliminate Tautologies
Don't:
<%= radio_button_tag 'date_field',
'created_at',
params[:date_field] == 'created_at' ? true : false
%>
Do:
<%= radio_button_tag 'date_field',
'created_at',
params[:date_field] == 'created_at' %>

8. Use update_column
update_attribute runs callbacks
update_column doesn't

9. Avoid nested_attributes
Complicated with AJAX and deep nested
associations
Alternatives:
- Do It Yourself
- Redtape (https://github.com/ClearFit/redtape)

10. Useful Gems
Annotate (Schema in models) https://github.com/ctran/annotate_models
Lograge (Better logs) https://github.com/roidrage/lograge
factory_girl (Better fixtures) https://github.com/thoughtbot/factory_girl
better_errors https://github.com/charliesome/better_errors

11. Let the DB Do its Work
Filling dates without value:
WITH filled_dates as (
select day, 0 as blank_count from generate_series('#{@start_date}', current_date::date, '1 day') as day
),
stats as (
SELECT COUNT(*) AS count, date_trunc('day', created_at) AS day
FROM "checkins" WHERE
(created_at >= '#{@start_date.to_s}')
GROUP BY date_trunc('day', created_at)
ORDER BY date_trunc('day', created_at)
)
SELECT date(filled_dates.day), coalesce(stats.count, filled_dates.blank_count) as count
FROM filled_dates
LEFT OUTER JOIN stats on stats.day = filled_dates.day
ORDER BY filled_dates.day;
Also: Postgresql uuid(), MD5(), etc.