Ruby - getting value of hash

ruby hash key-value
Sayuj picture Sayuj · Dec 30, 2011 · Viewed 92.8k times · Source

I have a hash like

{:key1 => "value1", :key2 => "value2"}

And I have a variable k which will have the value as 'key1' or 'key2'.

I want to get the value of k into a variable v.

Is there any way to achieve this with out using if or case? A single line solution is preferred. Please help.

Answer

Anurag picture Anurag · Dec 30, 2011

Convert the key from a string to a symbol, and do a lookup in the hash.

hash = {:key1 => "value1", :key2 => "value2"}
k = 'key1'

hash[k.to_sym] # or iow, hash[:key1], which will return "value1"

Rails uses this class called HashWithIndifferentAccess that proves to be very useful in such cases. I know that you've only tagged your question with Ruby, but you could steal the implementation of this class from Rails' source to avoid string to symbol and symbol to string conversions throughout your codebase. It makes the value accessible by using a symbol or a string as a key.

hash = HashWithIndifferentAccess.new({:key1 => "value1", :key2 => "value2"})
hash[:key1]  # "value1"
hash['key1'] # "value1"

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