I have a rake task that won’t work unless a table exists. I’m working with more than 20 engineers on a website so I want to make sure they have migrated the table before they can do a rake task which will populate that respective table. Does AR have a method such as Table.exists? How … Read more
Could you explain in detail what the :before_save and :before_create Ruby on Rails callbacks are, and what they have to do with Rails validations? Does validation occur after :before_save or :before_create? 3 Answers 3
I’m trying to create a new file and things don’t seem to be working as I expect them too. Here’s what I’ve tried: File.new “out.txt” File.open “out.txt” File.new “out.txt”,”w” File.open “out.txt”,”w” According to everything I’ve read online all of those should work but every single one of them gives me this: ERRNO::ENOENT: No such file … Read more
List the ruby versions console:~$ rvm list rvm rubies ruby-2.0.0-p481 [ i686 ] # => – current # =* – current && default # * – default Try to use a specific version of ruby console:~$ rvm use 2.0.0 RVM is not a function, selecting rubies with ‘rvm use …’ will not work. You need … Read more
This question already has answers here: Difference between “and” and && in Ruby? (8 answers) Closed 2 years ago. What’s the difference between the or and || operators in Ruby? Or is it just preference? 8 Answers 8
I am using Ruby on Rails 3.2.2 and I would like to know if the following is a “proper”https://stackoverflow.com/”correct”https://stackoverflow.com/”sure” way to override a setter method for a my class attribute. attr_accessible :attribute_name def attribute_name=(value) … # Some custom operation. self[:attribute_name] = value end The above code seems to work as expected. However, I would like … Read more
I’m using an IF statement in Ruby on Rails to try and test if request parameters are set. Regardless of whether or not both parameters are set, the first part of the following if block gets triggered. How can I make this part ONLY get triggered if both params[:one] and params[:two] is set? if (defined? … Read more
There are instances where I would like to revert and uninstall all previous gem installations. For instance, I needed to assist a friend migrate their rails development machine to use RVM. As they had been previously using the system-wide gem, he was experiencing many headaches when working with multiple projects. Essentially, he was the poster-child … Read more
I want to change every value in a hash so as to add ‘%’ before and after the value so { :a=>’a’ , :b=>’b’ } must be changed to { :a=>’%a%’ , :b=>’%b%’ } What’s the best way to do this? 11 Answers 11
I just uninstalled my older versions of Ruby, removed all of my gems (including Rails), and installed Ruby 2.0. In other words, a totally clean re-install. Upon starting IRB, I received this message: DL is deprecated, please use Fiddle Note: I’m on a Windows machine. What does this message mean? 5 Answers 5
