Building a hash in a conditional way

Question

I am using Ruby on Rails 3.0.10 and I would like to build an hash key\\value pairs in a conditional way. That is, I would like to add a key and its related value if a condition

Answer 1

First build your hash thusly:

hash = {
  :key1 => value1,
  :key2 => condition ? value2 : :delete_me,
  :key3 => value3
}

Then do this after building your hash:

hash.delete_if {|_, v| v == :delete_me}

Unless your hash is frozen or otherwise immutable, this would effectively only keep values that are present.