Rishi talks about writing clean code and avoid conditional blocks whenever and wherever feasible using Null Object Pattern.
Month: May 2015
Don’t test your code
I spoke at Agile India 2015 in March. Excellent conference but I was a quite disappointed that the videos are not publicly published. So, I decided to write about it here in detail. The slide deck has been published at on slideshare But here goes the picto-blog. This is an experience report - the story of … Continue reading Don’t test your code
Things To Remember While Working With Uniqueness In Rails
validation_uniqueness_of does not guarantee uniqueness. Interesting write-up by Yogesh about things to remember while working with uniqueness in Rails.
♦ The Problem
Consider the following relation where poll is having many options and each option of the poll must be having a unique description,
Now, when trying to create a poll with its options using nested attributes, uniqueness validation is not getting applied due to race condition.
> poll = Poll.new(options_attributes: [ { description: 'test' }, { description: 'test' } ])
> poll.save
=> true
>
> poll.options
=> [#<Option id: 1, description: "test">, #<Option id: 2, description: "test">]
♦ Why it is occurring ?
There is a section in UniquenessValidator class, which mentions that the ActiveRecord::Validations#save does not guarantee the prevention of duplicates because, uniqueness checks are performed at application level which are prone to race condition when creating/updating records at the same time. Also, while saving the records, UniquenessValidator is checking uniqueness against the records which are in database only, but not for the records which are…
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